US20140331998A1 - Determination of leak and respiratory airflow - Google Patents
Determination of leak and respiratory airflow Download PDFInfo
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- US20140331998A1 US20140331998A1 US14/278,642 US201414278642A US2014331998A1 US 20140331998 A1 US20140331998 A1 US 20140331998A1 US 201414278642 A US201414278642 A US 201414278642A US 2014331998 A1 US2014331998 A1 US 2014331998A1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0057—Pumps therefor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0057—Pumps therefor
- A61M16/0066—Blowers or centrifugal pumps
- A61M16/0069—Blowers or centrifugal pumps the speed thereof being controlled by respiratory parameters, e.g. by inhalation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/021—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes operated by electrical means
- A61M16/022—Control means therefor
- A61M16/024—Control means therefor including calculation means, e.g. using a processor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
- A61M2016/0015—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors
- A61M2016/0018—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors electrical
- A61M2016/0021—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors electrical with a proportional output signal, e.g. from a thermistor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
- A61M2016/0027—Accessories therefor, e.g. sensors, vibrators, negative pressure pressure meter
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
- A61M2016/003—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter
- A61M2016/0033—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
- A61M2016/003—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter
- A61M2016/0033—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical
- A61M2016/0036—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical in the breathing tube and used in both inspiratory and expiratory phase
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2205/00—General characteristics of the apparatus
- A61M2205/15—Detection of leaks
Definitions
- the invention relates to methods and apparatus for the determination of leakage airflow and true respiratory airflow, particularly during mechanical ventilation.
- the airflow determination can be for a subject who is either spontaneously or non-spontaneously breathing, or moves between these breathing states.
- the invention is especially suitable for, but not limited to, normally conscious and spontaneously breathing human subjects requiring long term ventilator assistance, particularly during sleep.
- any reference to a “mask” is to be understood as including all forms of devices for passing breathable gas to a person's airway, including nose masks, nose and mouth masks, nasal prongs/pillows and endotracheal or tracheostomy tubes.
- breathable gas is supplied for example via a mask, at a pressure which is higher during inspiration and lower during expiration. It is useful to measure the subject's respiratory airflow during mechanical ventilation to assess adequacy of treatment, or to control the operation of the ventilator.
- Respiratory airflow is commonly measured with a pneumotachograph placed in the gas delivery path between the mask and the ventilator. Leaks between the mask and the subject are unavoidable.
- the pneumotachograph measures the sum of the respiratory airflow plus the flow through the leak. If the instantaneous flow through the leak is known, the respiratory airflow can be calculated by subtracting the flow through the leak from the flow at the pneumotach.
- the known method is only correct if the pressure at the mask is constant. If the mask pressure varies with time (for example, in the case of a ventilator), assumption (i) above will be invalid, and the calculated respiratory airflow will therefore be incorrect. This is shown markedly in FIGS. 1 a - 1 f.
- FIG. 1A shows a trace of measured mask pressure in bi-level CPAP treatment between about 4 cm H 2 O on expiration and 12 cm H 2 O on inspiration.
- FIG. 1B shows a trace of true respiratory airflow in synchronism with the mask pressures.
- a mask leak occurs, resulting in a leakage flow from the leak that is a function of the treatment pressure, as shown in FIG. 1C .
- the measured mask flow shown in FIG. 1D now includes an offset due to the leak flow.
- the prior art method determines the calculated leak flow over a number of breaths, as shown in FIG. 1E .
- the resulting calculated respiratory flow as the measured flow minus the calculating leak flow is shown in FIG. 1F , having returned to the correct mean value, however is incorrectly scaled in magnitude, giving a false indication of peak positive and negative airflow.
- This method cannot be used if the moment of start and end of the previous breath are unknown. In general, it can be difficult to accurately calculate the time of start of a breath. This is particularly the case immediately following a sudden change in the leak.
- the method will not work in the case of a subject who is making no respiratory efforts, and is momentarily not being ventilated at all, for example during an apnea, because for the duration of the apnea there is no start or end of breath over which to make a calculation.
- the present invention seeks to provide a determination of leak flow and true respiratory airflow accounting for the variations in flow through a leak as a function of pressure.
- the invention discloses a method for determining instantaneous leak flow at a mask having a leak path during mechanical ventilation, the method comprising the steps of:
- the invention further discloses a method for determining instantaneous respiratory airflow for a subject receiving breathable gas by a mask and in the presence of any mask leak, the method comprising the steps of:
- the invention yet further discloses apparatus for determining respiratory airflow for a subject receiving breathable gas by a mask and in the presence of any mask leak, the apparatus comprising:
- transducer means located at or proximate the mask to determine instantaneous mask airflow and pressure
- processing means for estimating non-linear conductance or said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure, determining instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure, and calculating the respiratory air flows the instantaneous airflow minus the instantaneous leak flow.
- the invention yet further discloses apparatus for providing continuous positive airway pressure treatment or mechanical ventilation, the apparatus comprising:
- a mask having-connection to the delivery tube to supply said breathable gas to a subject's airway;
- transducer means located at or proximate the mask to determine instantaneous mask airflow and pressure
- processor means for estimating non-linear conductance of said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure, determining instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure, and calculating the respiratory airflow as the instantaneous airflow minus the instantaneous leak flow;
- control means to control the flow generator to, in turn, control the mask pressure and/or mask airflow on the basis of the calculated respiratory airflow.
- the invention yet further discloses a computer program for executing the steps referred to above.
- time constants of the low pass filtering are dynamically adjusted dependent upon sudden changes in the instantaneous leak flow.
- Embodiments of the invention provide advantages over the prior art. There is no need to know when transitions between respiratory phases occurs. The independence from knowledge of the subject's respiratory state has the important result that the leak flow calculation is accurate in apneic (i.e. no flow) instances on the part of the subject or the mechanical ventilator.
- FIGS. 1A-1F show trace of pressure and airflow from which respiratory airflow is calculated in accordance with a prior art method
- FIGS. 2A and B show schematic diagrams of two embodiments of ventilatory assistance apparatus
- FIG. 3 is a block flow diagram of a method for determining instantaneous respiratory airflow.
- FIGS. 4A-4H show traces of pressure, airflow and other variables from which respiratory airflow is calculated
- FIG. 5 shows a schematic diagram of ventilatory assistance apparatus of another embodiment
- FIG. 6 shows a fuzzy membership function for the calculation of the extent A 1 to which the time t X1 since the most recent positive going zero crossing of the calculated respiratory airflow is longer than the expected time T 1 ;
- FIG. 7 shows a fuzzy membership function for the calculation of the extent B 1 to which the calculated inspiratory respiratory airflow f RESP is large positive
- FIG. 8 shows a fuzzy membership function for the calculation of the extent A E to which the time t ZE since the most recent negative going zero crossing in the calculated respiratory airflow is longer than the expected time T E ;
- FIG. 9 shows a fuzzy membership function for the calculation of the extent B E to which the respiratory airflow f RESP is large negative.
- FIG. 10 shows the relation between an index J and time constant ⁇ .
- FIG. 2A shows mechanical ventilation apparatus 10 embodying the invention.
- the subject/patient wears a nose mask 12 of any known type.
- the subject equally could wear a face mask or nasal prongs/pillows, or alternatively have an endotracheal tube or tracheostomy tube in place.
- a turbine/blower 14 operated by a mechanically coupled electrical motor 16 , receives air or breathable gas at an inlet 18 thereof, and supplies the breathable gas at a delivery pressure to a delivery tube/hose 20 having connection at the other end thereof with the nose mask 12 .
- Breathable gas thus is provided to the subject's airway for the purpose of providing assisted respiration, with the subject's expired breath passing to atmosphere by an exhaust 22 in the delivery tube 20 , typically located proximate to the mask 12 .
- a pneumotachograph 24 is placed in the delivery tube between the mask 12 and the exhaust 22 to provide two pressure signals, P 2 and P 1 , across the pneumotachograph, each passed by hoses 28 , 30 to a differential pressure sensor 32 .
- a determination of the flow of gas in the mask 12 is made the differential pressure, P 2 ⁇ P 1 , resulting in a flow signal f d .
- the mask pressure, P 2 also is passed to a pressure sensor 34 by a tapped line 36 taken from the respective hose 28 , to generate a delivery pressure signal, p m , output from the pressure sensor 34 .
- Both the flow signal, f d , and the pressure signal p m are passed to a microcontroller 38 where they are sampled for subsequent signal processing, typically at a rate of 50 Hz.
- the microcontroller 38 is programmed to process the flow and pressure signals (f d , P m ) to produce an output control signal, y o , provided to an electronic motor servo-controller 42 that, in turn, produces a motor speed control output signal, v o .
- This signal is provided to the motor 16 to control the rotational speed of the turbine 14 and provide the desired treatment pressure, P 2 , at the nose mask 12 .
- the motor servo-controller 42 employs a negative feedback control technique that compares the actual delivery pressure, in the form of the signal P m , with the control signal y o .
- this control stratagem may be independent of operation of the microcontroller 38 .
- Operation of the controlling of the microcontroller 38 so far as a calculation of respiratory airflow is concerned, broadly is as follows. In a sampled manner, the conductance of any mask leak is calculated then the instantaneous flow through the leak is calculated. The flow through the leak is subtracted from the total mask flow to calculate the true instantaneous respiratory airflow.
- FIG. 2B shows an alternative embodiment of a system for determining true respiratory airflow during mechanical ventilation.
- the mechanical ventilation system 10 of FIG. 1B differs from that of FIG. 1A firstly in that the microcontroller 38 plays no part in control of the ventilator 50 , rather only receives and data processes the electrically transduced mask pressure and flow signals P m , f d to determine and generate the instantaneous respiratory flow f RESP .
- the ventilator 50 has an internal drive signal provided by an oscillator 44 .
- the motor servo controller also may or may not receive the mask pressure signal p m as a form of feedback control. Indeed, the ventilator 50 can be realized by any convenient form of known generic ventilation device.
- the controlling software resident within the microcontroller 38 performs the following steps in determining the respiratory airflow as broadly described above, as also shown in the flow diagram of FIG. 3 .
- the word “average” is used herein in the most general sense of the result of a low pass filtering step, and is not confined to an arithmetic mean.
- the leak flow has been determined, such as would be desired for a leak flow detector. If desired, the instantaneous respiratory airflow can be subsequently determined by the following step.
- FIGS. 4A-4H illustrate the methodology of the embodiment described above with reference to FIG. 2B .
- FIG. 4E shows the mean mask flow.
- FIG. 4F represents the calculated conductance G, from which the mask leak flow can be estimated as shown in FIG. 4G .
- FIG. 4H shows how the calculated respiratory airflow recovers within approximately 30 seconds, and, importantly, gives the correctly scaled (true) magnitude of airflow.
- the microcontroller broadly executes the following steps:
- y o is set to a value corresponding to an inspiratory pressure, P INSP . Otherwise y o is set to a value corresponding to an expiratory pressure, P EXP .
- P INSP is higher than P EXP , but in the case of continuous positive airways pressure, P EXP may be equal to P INSP .
- step 7 many other methods of determining y o from f MASK may be used in step 7, for example as descried in the text Principles and Practice of Mechanical Ventilation , edited by Martin J. Tobin (McGraw Hill Inc. 1994).
- the ventilation delivered by the assisted ventilation apparatus is greater than the ventilation delivered to the subject.
- Known devices which servo-control ventilation cope with this by collecting the exhaled air stream with a complex system of valves, and then measuring the exhaled ventilation. This is inappropriate for devices for use in a domestic setting during sleep, because of the attendant weight, complexity, and expense.
- the embodiment described compensates for the leak by continuously measuring the nonlinear conductance of the leak, and allowing for the instantaneous flow through the leak as a function of pressure.
- FIG. 5 shows an alternate arrangement for ventilatory assistance apparatus 10 ′ embodying the invention.
- the pneumotachograph 24 ′ is interposed between the turbine 14 and the delivery hose 20 .
- This arrangement removes the pressure sensing hoses and pneumotachograph from the region of the mask 12 .
- the pressure at the mask, P MASK is calculated from the delivery pressure at the turbine 14 , and from the pressure drop down the air delivery hose 20 , which for any particular delivery hose is a known function of the flow at the pneumotachograph 24 .
- the microcontroller 38 must also calculate the flow through the mask from the flow at the turbine 14 less the flow through the exhaust 22 , which for any particular exhaust is a known function of the pressure at the mask 12 .
- this involves the steps of, firstly measuring the pressure P 3 at the turbine 14 with the pressure sensor 34 to produce an electrical signal P t .
- the differential pressure P 4 ⁇ P 3 is measured across the pneumotachograph 24 ′ by the differential pressure sensor 32 to produce an electrical signal f t .
- P t and f t are digitized to yield the sampled turbine pressure and flow signals P TURBINE and F TURBINE .
- the pressure at the mask P MASK and the sampled airflow at the mask f MASK 12 are calculated from the turbine pressure P TURBINE and the flow at the outlet of the turbine F TURBINE as follows:
- the foregoing embodiments describe low-pass filtering of both the instantaneous airflow and the square root of the instantaneous pressure with a time constant ⁇ of 10 seconds.
- This time constant ⁇ can be advantageously dynamically adjustable.
- the conductance of the leak suddenly changes, then the calculated conductance will initially be incorrect, and will gradually approach the correct value at a rate which will be slow if the time constant of the low pass filters is long, and fast if the time constant is short. Conversely, if the impedance of the leak is steady, the longer the time constant the more accurate the calculation of the instantaneous leak. Therefore, it is desirable to lengthen the time constant if it is certain that the leak is steady, reduce the time constant if it is certain that the leak has suddenly changed, and to use intermediately longer or shorter time constants if it is intermediately certain that the leak is steady.
- the calculated respiratory airflow will be incorrect. In particular during apparent inspiration, the calculated respiratory airflow will be large positive for a time that is large compared with the expect duration of a normal inspiration. Conversely, if there is a sudden decrease in conductance of the leak, then during apparent expiration the calculated respiratory airflow will be large negative for a time that is large compared with the duration of normal expiration.
- an index of the degree of certainty that the leak has suddenly changed is derived, such that the longer the airflow has been away from zero, and by a larger amount, the larger the index; and the time constant for the low pass filters is adjusted to vary inversely with the index.
- the index will be large, and the time constant for the calculation of the conductance of the leak will be small, allowing rapid convergence on the new value of the leakage conductance.
- the index will be small, and the time constant for calculation of the leakage conductance will be large, enabling accurate calculation of the instantaneous respiratory airflow.
- the index will be progressively larger, and the time constant for the calculation of the leak will progressively reduce.
- the index will be of an intermediate value, and the time constant for calculation of the impedance of the leak will also be of an intermediate value.
- Another advantage is that there is never a moment where the leak correction algorithm is “out of control” and needs to be restarted, as described for prior art European Patent Publication No. 0 714 670 A2.
- the above index is derived using fuzzy logic.
- the fuzzy extent A I to which the airflow has been positive for longer than expected is calculated from the time t ZI since the last positive-going zero crossing of the calculated respiratory airflow signal, and the expected duration T I of a normal inspiration for the particular subject, using the fuzzy membership function shown in FIG. 6 .
- the fuzzy extent B 1 to which the airflow is large and positive is calculated from the instantaneous respiratory airflow using the fuzzy membership function shown in FIG. 7 .
- the instantaneous index I I of the degree of certainty that the leak has suddenly increased is calculated as the fuzzy intersection (lesser) of A I and B I .
- Comparable calculations are performed for expiration as follows.
- the fuzzy extent A E to which the airflow has been negative for longer than expected is calculated from the time t ZE since the last negative-going zero crossing of the calculated respiratory airflow signal, and T E , the expected duration of a typical expiration for the particular subject, using the membership function shown in FIG. 8 .
- the fuzzy extent B E to which the airflow is large negative is calculated from the instantaneous respiratory airflow using the fuzzy membership function shown in FIG. 9 .
- the instantaneous index I E of the degree of certainty that the leak has suddenly decreased is calculated as the fuzzy intersection of A E and B E .
- the instantaneous index I of the extent to which there has been a sudden change in the leak is calculated as the fuzzy union (larger) of indices I I and I E .
- the instantaneous index I is then passed through a peak detector followed by a low pass filter with a time constant of, for example 2 seconds, to yield the desired index J.
- time constant ⁇ for the low pass filters used in the calculation of the conductance of the leak is then adjusted to vary inversely with the index J, as shown in FIG. 10 .
- the time constant is set to 10 seconds if the index J is zero, (corresponding to complete certainty that the leak is steady), and to 1 second if the index J is unity (corresponding to complete certainty that the leak is suddenly changing), and to intermediate values for intermediate cases.
- the embodiments described refer to apparatus for the provision of ventialatory assistance, however, it is to be understood that the invention is applicable to all forms of mechanical ventilation and apparatus for the provision of continuous positive airway pressure treatment.
- the apparatus can be for the provision of a constant treatment pressure, multi-level (IPAP and EPAP) treatment or autosetting (adjusting) treatment or other forms of mechanical ventilation, including Proportional Assist Ventilation (PAV) as taught by M Younes in the above-noted text.
- PAV Proportional Assist Ventilation
- the methodology described can be implemented in the form of a computer program that is executed by the microcontroller described, or by discrete combinational logic elements, or by analog hardware.
Abstract
Methods and apparatus for determining leak and respiratory airflow are disclosed. A pressure sensor (34) and a differential pressure sensor (32) have connection with a pneumotach (24) to derive instantaneous mask pressure and airflow respectively. A microcontroller (38) estimates a non-linear conductance of any leak path occurring at a mask (12) as being the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure. The instantaneous leak flow is then the conductance multiplied by the square root of the instantaneous pressure, and the respiratory airflow is calculated as being the instantaneous airflow minus the instantaneous leak flow. The time constants for the low pass filtering performed by the microcontroller (38) can be dynamically adjusted dependent upon sudden changes in the instantaneous leak flow.
Description
- The present application is a continuation of application Ser. No. 12/649,877 filed on Dec. 30, 2009, now allowed, which is a continuation of application Ser. No. 11/223,237 filed on Sep. 8, 2005, now U.S. Pat. No. 7,661,428; which is a continuation of application Ser. No. 10/726,114 filed on Dec. 1, 2003, now U.S. Pat. No. 6,945,248; which is a continuation of application Ser. No. 09/902,011 filed on Jul. 10, 2001, now U.S. Pat. No. 6,659,101; which is a continuation of application Ser. No. 09/525,042 filed on Mar. 14, 2000, now U.S. Pat. No. 6,279,569; which is a continuation of application Ser. No. 08/911,513 filed on Aug. 14, 1997, now U.S. Pat. No. 6,152,129 and Australian Application No. AU199737625 filed on Aug. 14, 1996, the disclosures of which are incorporated herein by reference.
- The invention relates to methods and apparatus for the determination of leakage airflow and true respiratory airflow, particularly during mechanical ventilation.
- The airflow determination can be for a subject who is either spontaneously or non-spontaneously breathing, or moves between these breathing states. The invention is especially suitable for, but not limited to, normally conscious and spontaneously breathing human subjects requiring long term ventilator assistance, particularly during sleep.
- In this specification any reference to a “mask” is to be understood as including all forms of devices for passing breathable gas to a person's airway, including nose masks, nose and mouth masks, nasal prongs/pillows and endotracheal or tracheostomy tubes.
- During mechanical ventilation, breathable gas is supplied for example via a mask, at a pressure which is higher during inspiration and lower during expiration. It is useful to measure the subject's respiratory airflow during mechanical ventilation to assess adequacy of treatment, or to control the operation of the ventilator.
- Respiratory airflow is commonly measured with a pneumotachograph placed in the gas delivery path between the mask and the ventilator. Leaks between the mask and the subject are unavoidable. The pneumotachograph measures the sum of the respiratory airflow plus the flow through the leak. If the instantaneous flow through the leak is known, the respiratory airflow can be calculated by subtracting the flow through the leak from the flow at the pneumotach.
- Known methods to correct for the flow through the leak assume (i) that the leak is substantially constant, and (ii) that over a sufficiently long time, inspiratory and expiratory respiratory airflow will cancel. If these assumptions are met, the average flow through the pneumotach over a sufficiently long period will equal the magnitude of the leak, and the true respiratory airflow may then be calculated as described.
- The known method is only correct if the pressure at the mask is constant. If the mask pressure varies with time (for example, in the case of a ventilator), assumption (i) above will be invalid, and the calculated respiratory airflow will therefore be incorrect. This is shown markedly in
FIGS. 1 a-1 f. -
FIG. 1A shows a trace of measured mask pressure in bi-level CPAP treatment between about 4 cm H2O on expiration and 12 cm H2O on inspiration.FIG. 1B shows a trace of true respiratory airflow in synchronism with the mask pressures. At time=21 seconds a mask leak occurs, resulting in a leakage flow from the leak that is a function of the treatment pressure, as shown inFIG. 1C . The measured mask flow shown inFIG. 1D now includes an offset due to the leak flow. The prior art method then determines the calculated leak flow over a number of breaths, as shown inFIG. 1E . The resulting calculated respiratory flow, as the measured flow minus the calculating leak flow is shown inFIG. 1F , having returned to the correct mean value, however is incorrectly scaled in magnitude, giving a false indication of peak positive and negative airflow. - Another prior art arrangement is disclosed in European Publication No. 0714670 A2, including a calculation of a pressure-dependent leak component. The methodology relies on knowing precisely the occurrence of the start of an inspiratory event and the start of the next inspiratory event. In other words, the leak calculation is formed as an average over a known breath and applied to a subsequent breath.
- This method cannot be used if the moment of start and end of the previous breath are unknown. In general, it can be difficult to accurately calculate the time of start of a breath. This is particularly the case immediately following a sudden change in the leak.
- Furthermore, the method will not work in the case of a subject who is making no respiratory efforts, and is momentarily not being ventilated at all, for example during an apnea, because for the duration of the apnea there is no start or end of breath over which to make a calculation.
- The present invention seeks to provide a determination of leak flow and true respiratory airflow accounting for the variations in flow through a leak as a function of pressure.
- The invention discloses a method for determining instantaneous leak flow at a mask having a leak path during mechanical ventilation, the method comprising the steps of:
- (a) determining instantaneous airflow at the mask;
- (b) determining instantaneous pressure at the mask;
- (c) estimating non-linear conductance of said leak path as the low-pass filtered instantaneous airflow divided by the low-pass filtered square root of the instantaneous pressure; and
- (d) determining said instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure.
- The invention further discloses a method for determining instantaneous respiratory airflow for a subject receiving breathable gas by a mask and in the presence of any mask leak, the method comprising the steps of:
- (a) determining instantaneous airflow at the mask;
- (b) determining instantaneous pressure at the mask;
- (c) estimating non-linear conductance of said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure;
- (d) determining instantaneous leak flow to the said conductance multiplied by the square root of the said instantaneous pressure; and
- (e) calculating the respiratory airflow as the instantaneous air flow minus the instantaneous leak flow.
- The invention yet further discloses apparatus for determining respiratory airflow for a subject receiving breathable gas by a mask and in the presence of any mask leak, the apparatus comprising:
- transducer means located at or proximate the mask to determine instantaneous mask airflow and pressure; and
- processing means for estimating non-linear conductance or said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure, determining instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure, and calculating the respiratory air flows the instantaneous airflow minus the instantaneous leak flow.
- The invention yet further discloses apparatus for providing continuous positive airway pressure treatment or mechanical ventilation, the apparatus comprising:
- a turbine for the generation of a supply of breathable gas;
- a gas delivery tube having connection with the turbine;
- a mask having-connection to the delivery tube to supply said breathable gas to a subject's airway;
- transducer means located at or proximate the mask to determine instantaneous mask airflow and pressure;
- processor means for estimating non-linear conductance of said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure, determining instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure, and calculating the respiratory airflow as the instantaneous airflow minus the instantaneous leak flow; and
- control means to control the flow generator to, in turn, control the mask pressure and/or mask airflow on the basis of the calculated respiratory airflow.
- The invention yet further discloses a computer program for executing the steps referred to above.
- In one preferred form, time constants of the low pass filtering are dynamically adjusted dependent upon sudden changes in the instantaneous leak flow.
- Embodiments of the invention provide advantages over the prior art. There is no need to know when transitions between respiratory phases occurs. The independence from knowledge of the subject's respiratory state has the important result that the leak flow calculation is accurate in apneic (i.e. no flow) instances on the part of the subject or the mechanical ventilator.
- Embodiments of the invention will now be described with reference to the accompanying drawings in which:
-
FIGS. 1A-1F show trace of pressure and airflow from which respiratory airflow is calculated in accordance with a prior art method; -
FIGS. 2A and B show schematic diagrams of two embodiments of ventilatory assistance apparatus; -
FIG. 3 is a block flow diagram of a method for determining instantaneous respiratory airflow; and -
FIGS. 4A-4H show traces of pressure, airflow and other variables from which respiratory airflow is calculated; -
FIG. 5 shows a schematic diagram of ventilatory assistance apparatus of another embodiment; -
FIG. 6 shows a fuzzy membership function for the calculation of the extent A1 to which the time tX1 since the most recent positive going zero crossing of the calculated respiratory airflow is longer than the expected time T1; -
FIG. 7 shows a fuzzy membership function for the calculation of the extent B1 to which the calculated inspiratory respiratory airflow fRESP is large positive; -
FIG. 8 shows a fuzzy membership function for the calculation of the extent AE to which the time tZE since the most recent negative going zero crossing in the calculated respiratory airflow is longer than the expected time TE; -
FIG. 9 shows a fuzzy membership function for the calculation of the extent BE to which the respiratory airflow fRESP is large negative; and -
FIG. 10 shows the relation between an index J and time constant τ. -
FIG. 2A showsmechanical ventilation apparatus 10 embodying the invention. - The subject/patient wears a
nose mask 12 of any known type. The subject equally could wear a face mask or nasal prongs/pillows, or alternatively have an endotracheal tube or tracheostomy tube in place. A turbine/blower 14, operated by a mechanically coupledelectrical motor 16, receives air or breathable gas at aninlet 18 thereof, and supplies the breathable gas at a delivery pressure to a delivery tube/hose 20 having connection at the other end thereof with thenose mask 12. Breathable gas thus is provided to the subject's airway for the purpose of providing assisted respiration, with the subject's expired breath passing to atmosphere by anexhaust 22 in thedelivery tube 20, typically located proximate to themask 12. - A
pneumotachograph 24 is placed in the delivery tube between themask 12 and theexhaust 22 to provide two pressure signals, P2 and P1, across the pneumotachograph, each passed byhoses differential pressure sensor 32. A determination of the flow of gas in themask 12 is made the differential pressure, P2−P1, resulting in a flow signal fd. The mask pressure, P2, also is passed to apressure sensor 34 by a tappedline 36 taken from therespective hose 28, to generate a delivery pressure signal, pm, output from thepressure sensor 34. - Both the flow signal, fd, and the pressure signal pm, are passed to a
microcontroller 38 where they are sampled for subsequent signal processing, typically at a rate of 50 Hz. - The
microcontroller 38 is programmed to process the flow and pressure signals (fd, Pm) to produce an output control signal, yo, provided to an electronic motor servo-controller 42 that, in turn, produces a motor speed control output signal, vo. This signal is provided to themotor 16 to control the rotational speed of theturbine 14 and provide the desired treatment pressure, P2, at thenose mask 12. - The motor servo-
controller 42 employs a negative feedback control technique that compares the actual delivery pressure, in the form of the signal Pm, with the control signal yo. For convenience, this control stratagem may be independent of operation of themicrocontroller 38. - Operation of the controlling of the
microcontroller 38, so far as a calculation of respiratory airflow is concerned, broadly is as follows. In a sampled manner, the conductance of any mask leak is calculated then the instantaneous flow through the leak is calculated. The flow through the leak is subtracted from the total mask flow to calculate the true instantaneous respiratory airflow. -
FIG. 2B shows an alternative embodiment of a system for determining true respiratory airflow during mechanical ventilation. Themechanical ventilation system 10 ofFIG. 1B differs from that ofFIG. 1A firstly in that themicrocontroller 38 plays no part in control of theventilator 50, rather only receives and data processes the electrically transduced mask pressure and flow signals Pm, fd to determine and generate the instantaneous respiratory flow fRESP. Theventilator 50 has an internal drive signal provided by anoscillator 44. The motor servo controller also may or may not receive the mask pressure signal pm as a form of feedback control. Indeed, theventilator 50 can be realized by any convenient form of known generic ventilation device. - The controlling software resident within the
microcontroller 38 performs the following steps in determining the respiratory airflow as broadly described above, as also shown in the flow diagram ofFIG. 3 . - The word “average” is used herein in the most general sense of the result of a low pass filtering step, and is not confined to an arithmetic mean.
- 1. Repeatedly sample the mask airflow fd to give a sampled signal fMASK for example at intervals of T=20 milliseconds. (Steps 50,52).
- 2. Calculate the average leak, LP(L), as being the result of low pass filtering the airflow, fMASK with a time constant of 10 seconds. (Step 54).
- 3. Calculate the average of the square root of the mask pressure, LP(√{square root over (PMASK)}), as being the result of low pass filtering the square root of the mask pressure, PMASK, with a time constant of 10 seconds. (Step 56).
- 4. Calculate the conductane, G, of any leak (Step 58), from the equation:
-
G=LP(L)/LP(√{square root over (PMASK)}) - 5. Calculate the instantaneous leak flow, fLEAK, through the leak (Step 60), from the equation:
-
f LEAK =G√{square root over (PMASK)} - If there is no leak flow, the value of LP(L) will be equal to zero, as will G and hence fLEAK. Thus the methodology is valid also where leak is equal to zero—no leak.
- At this juncture the leak flow has been determined, such as would be desired for a leak flow detector. If desired, the instantaneous respiratory airflow can be subsequently determined by the following step.
- 6. Calculate the instantaneous respiratory airflow, fRESP, by subtracting the instantaneous leak from the mask flow (Step 62):
-
f RESP =f MASK −f LEAK -
FIGS. 4A-4H illustrate the methodology of the embodiment described above with reference toFIG. 2B . At time, t=21 sec. a continuing leak of approximately 1 L/sec is introduced.FIG. 4E shows the mean mask flow.FIG. 4F represents the calculated conductance G, from which the mask leak flow can be estimated as shown inFIG. 4G . Finally,FIG. 4H shows how the calculated respiratory airflow recovers within approximately 30 seconds, and, importantly, gives the correctly scaled (true) magnitude of airflow. - With regard to setting the instantaneous output signal yo, the microcontroller broadly executes the following steps:
- 7. If the calculated true respiratory airflow fRESP is above a threshold, for example 0.05 L/sec. yo is set to a value corresponding to an inspiratory pressure, PINSP. Otherwise yo is set to a value corresponding to an expiratory pressure, PEXP. In general, PINSP is higher than PEXP, but in the case of continuous positive airways pressure, PEXP may be equal to PINSP. (Step 66).
- It is to be understood that many other methods of determining yo from fMASK may be used in step 7, for example as descried in the text Principles and Practice of Mechanical Ventilation, edited by Martin J. Tobin (McGraw Hill Inc. 1994).
- In order to control ventilation, it is necessary to measure the subject's ventilation. In the presence of a leak, the ventilation delivered by the assisted ventilation apparatus is greater than the ventilation delivered to the subject. Known devices which servo-control ventilation cope with this by collecting the exhaled air stream with a complex system of valves, and then measuring the exhaled ventilation. This is inappropriate for devices for use in a domestic setting during sleep, because of the attendant weight, complexity, and expense. The embodiment described compensates for the leak by continuously measuring the nonlinear conductance of the leak, and allowing for the instantaneous flow through the leak as a function of pressure.
-
FIG. 5 shows an alternate arrangement forventilatory assistance apparatus 10′ embodying the invention. In this arrangement, thepneumotachograph 24′ is interposed between theturbine 14 and thedelivery hose 20. - This arrangement removes the pressure sensing hoses and pneumotachograph from the region of the
mask 12. The pressure at the mask, PMASK is calculated from the delivery pressure at theturbine 14, and from the pressure drop down theair delivery hose 20, which for any particular delivery hose is a known function of the flow at thepneumotachograph 24. Further, themicrocontroller 38 must also calculate the flow through the mask from the flow at theturbine 14 less the flow through theexhaust 22, which for any particular exhaust is a known function of the pressure at themask 12. - In more detail, this involves the steps of, firstly measuring the pressure P3 at the
turbine 14 with thepressure sensor 34 to produce an electrical signal Pt. Next the differential pressure P4−P3 is measured across thepneumotachograph 24′ by thedifferential pressure sensor 32 to produce an electrical signal ft. In a sampled manner, Pt and ft are digitized to yield the sampled turbine pressure and flow signals PTURBINE and FTURBINE. - The pressure at the mask PMASK and the sampled airflow at the
mask f MASK 12 are calculated from the turbine pressure PTURBINE and the flow at the outlet of the turbine FTURBINE as follows: - Calculate the pressure drop AP TUBE down the
air delivery tube 20, from the flow at the outlet of the turbine FTURBINE: -
ΔP TUBE=sign(F TURBINE)×K 1(F TURBINE)2 +K 2 F TURBINE -
- where K1 and K2 are empirically determined constants, and sign (x) is 1 for x≧0 and −1 otherwise.
- Calculate the pressure at the mask, PMASK, as the pressure at the turbine PTURBINE less the pressure drop ΔPTUBE down the
air delivery tube 20. -
P MASK =P TURBINE −ΔP TUBE - Calculate the flow fEXHAUST through the
exhaust 22, from the pressure at the mask PMASK: -
f EXHAUST=Sign(P MASK)×K 3√{square root over (absPMASK)} -
- where K3 is determined empirically.
- Calculate the flow, fMASK, into the
mask 12 as the flow at theturbine 14 less the flow through the exhaust 22: -
f MASK =f TURBINE −f EXHAUST - The foregoing embodiments describe low-pass filtering of both the instantaneous airflow and the square root of the instantaneous pressure with a time constant τ of 10 seconds. This time constant τ, can be advantageously dynamically adjustable.
- If the conductance of the leak suddenly changes, then the calculated conductance will initially be incorrect, and will gradually approach the correct value at a rate which will be slow if the time constant of the low pass filters is long, and fast if the time constant is short. Conversely, if the impedance of the leak is steady, the longer the time constant the more accurate the calculation of the instantaneous leak. Therefore, it is desirable to lengthen the time constant if it is certain that the leak is steady, reduce the time constant if it is certain that the leak has suddenly changed, and to use intermediately longer or shorter time constants if it is intermediately certain that the leak is steady.
- If there is a large and sudden increase in the conductance of the leak, then the calculated respiratory airflow will be incorrect. In particular during apparent inspiration, the calculated respiratory airflow will be large positive for a time that is large compared with the expect duration of a normal inspiration. Conversely, if there is a sudden decrease in conductance of the leak, then during apparent expiration the calculated respiratory airflow will be large negative for a time that is large compared with the duration of normal expiration.
- Therefore, an index of the degree of certainty that the leak has suddenly changed is derived, such that the longer the airflow has been away from zero, and by a larger amount, the larger the index; and the time constant for the low pass filters is adjusted to vary inversely with the index. In operation, if there is a sudden and large change in the leak, the index will be large, and the time constant for the calculation of the conductance of the leak will be small, allowing rapid convergence on the new value of the leakage conductance. Conversely, if the leak is steady for a long time, the index will be small, and the time constant for calculation of the leakage conductance will be large, enabling accurate calculation of the instantaneous respiratory airflow. In the spectrum of intermediate situations, where the calculated instantaneous respiratory airflow is larger and for longer periods, the index will be progressively larger, and the time constant for the calculation of the leak will progressively reduce. For example, at a moment in time where it is uncertain whether the leak is in fact constant, and the subject merely commenced a large sigh, or whether in fact there has been a sudden increase in the leak, the index will be of an intermediate value, and the time constant for calculation of the impedance of the leak will also be of an intermediate value. One advantage is that some corrective action will occur very early.
- Another advantage is that there is never a moment where the leak correction algorithm is “out of control” and needs to be restarted, as described for prior art European Patent Publication No. 0 714 670 A2.
- In a preferred embodiment, the above index is derived using fuzzy logic. The fuzzy extent AI to which the airflow has been positive for longer than expected is calculated from the time tZI since the last positive-going zero crossing of the calculated respiratory airflow signal, and the expected duration TI of a normal inspiration for the particular subject, using the fuzzy membership function shown in
FIG. 6 . The fuzzy extent B1 to which the airflow is large and positive is calculated from the instantaneous respiratory airflow using the fuzzy membership function shown inFIG. 7 . The instantaneous index II of the degree of certainty that the leak has suddenly increased is calculated as the fuzzy intersection (lesser) of AI and BI. - Comparable calculations are performed for expiration as follows. The fuzzy extent AE to which the airflow has been negative for longer than expected is calculated from the time tZE since the last negative-going zero crossing of the calculated respiratory airflow signal, and TE, the expected duration of a typical expiration for the particular subject, using the membership function shown in
FIG. 8 . The fuzzy extent BE to which the airflow is large negative is calculated from the instantaneous respiratory airflow using the fuzzy membership function shown inFIG. 9 . The instantaneous index IE of the degree of certainty that the leak has suddenly decreased is calculated as the fuzzy intersection of AE and BE. - The instantaneous index I of the extent to which there has been a sudden change in the leak (either an increase or a decrease) is calculated as the fuzzy union (larger) of indices II and IE. The instantaneous index I is then passed through a peak detector followed by a low pass filter with a time constant of, for example 2 seconds, to yield the desired index J. Thus if index I becomes momentarily large, index J will be initially large and remain so for a few seconds. The time constant τ for the low pass filters used in the calculation of the conductance of the leak is then adjusted to vary inversely with the index J, as shown in
FIG. 10 . For example, if the expected duration of a normal respiratory cycle were 4 seconds the time constant is set to 10 seconds if the index J is zero, (corresponding to complete certainty that the leak is steady), and to 1 second if the index J is unity (corresponding to complete certainty that the leak is suddenly changing), and to intermediate values for intermediate cases. - The embodiments described refer to apparatus for the provision of ventialatory assistance, however, it is to be understood that the invention is applicable to all forms of mechanical ventilation and apparatus for the provision of continuous positive airway pressure treatment. The apparatus can be for the provision of a constant treatment pressure, multi-level (IPAP and EPAP) treatment or autosetting (adjusting) treatment or other forms of mechanical ventilation, including Proportional Assist Ventilation (PAV) as taught by M Younes in the above-noted text.
- The methodology described can be implemented in the form of a computer program that is executed by the microcontroller described, or by discrete combinational logic elements, or by analog hardware.
- Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
Claims (39)
1. A method for determining instantaneous leak flow at a mask having a leak path during mechanical ventilation, the method comprising the steps of:
a) determining instantaneous airflow at the mask;
b) determining instantaneous pressure at the mask;
c) estimating non-linear conductance of said leak path as the low-pass filtered instantaneous airflow divided by the low-pass filtered square root of the instantaneous pressure; and
d) determining said instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure.
2. A method for determining instantaneous respiratory airflow for a subject receiving breathable gas by a mask and in the presence of any mask leak, the method comprising the steps of:
a) determining instantaneous airflow at the mask;
b) determining instantaneous pressure at the mask;
c) estimating non-linear conductance of said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure; and
d) determining said instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure; and
e) calculating the respiratory airflow as the instantaneous airflow minus the instantaneous leak flow.
3. A method as claimed in claim 2 , whereby the time constants for said low pass filtering are dynamically adjustable dependent upon sudden changes in said instantaneous leak flow.
4. A method as claimed in claim 3 , whereby said dynamic adjustment comprises the further steps of:
deriving an index of the extent to which said conductance has changed suddenly; and
changing said time constants in an opposite sense to a corresponding change in said index.
5. A method as claimed in claim 4 , whereby said index is derived by the steps of:
from said calculated respiratory airflow, determining the extent to which the absolute magnitude of calculated airflow is larger than expected for longer than expected.
6. A method as claimed in claim 2 , whereby steps (a) and (b) comprise:
measuring airflow and pressure in a gas delivery circuit coupled to said mask;
calculating the pressure drop along the delivery circuit to the mask as a function of said delivery circuit airflow; and
calculating a derived said instantaneous mask pressure as the measured delivery circuit pressure less the pressure drop; and
calculating the airflow through an exhaust of the mask as a function of the derived instantaneous mask pressure; and
calculating a derived said mask airflow as the measured delivery circuit airflow minus the exhaust airflow.
7. Apparatus for determining respiratory airflow for a subject receiving breathable gas by a mask and in the presence of any mask leak, the apparatus comprising:
transducer means located at or proximate the mask to determine instantaneous mask airflow and pressure; and
processing means for estimating non-linear conductance of said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure, determining instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure, and calculating the respiratory airflow as the instantaneous airflow minus the instantaneous leak flow.
8. Apparatus as claimed in claim 7 , wherein the time constants for said low pass filtering are dynamically adjustable dependent upon sudden changes in said instantaneous leak flow.
9. Apparatus as claimed in claim 8 , wherein said processor means dynamically adjusts the time constants by deriving an index of the extent to which said conductance has changed suddenly, and changing said time constants in an opposite sense to a corresponding change in said index.
10. Apparatus as claimed in claim 9 , wherein said processor means derives said index from said calculated respiratory airflow by determining the extent to which the absolute magnitude of calculated airflow is larger than expected for longer than expected.
11. Apparatus as claimed in claim 7 , wherein said transducer means comprises a pneumotachograph coupled to a differential pressure transducer.
12. Apparatus as claimed in claim 11 , wherein said pneumotachograph is located between the mask and the mask exhaust.
13. Apparatus as claimed in claim 11 , wherein said transducer means is located in a gas delivery circuit connected with said mask and remote from said mask.
14. Apparatus for providing continuous positive airway pressure treatment or mechanical ventilation, the apparatus comprising:
a turbine for the generation of a supply of breathable gas;
a gas delivery tube having connection with the turbine;
a mask having connection to the delivery tube to supply said breathable gas to a subject's airway;
transducer means located at or proximate the mask to determine instantaneous mask airflow and pressure;
processor means for estimating non-linear conductance of said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure, determining instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure, and calculating the respiratory airflow as the instantaneous airflow minus the instantaneous leak flow; and
control means to control the flow generator to, in turn, control the mask pressure and/or mask airflow on the basis of the calculated respiratory airflow.
15. Apparatus as claimed in claim 14 , wherein the time constants for said low pass filtering are dynamically adjustable dependent upon sudden changes in said instantaneous leak flow.
16. Apparatus as claimed in claim 15 , wherein said processor means dynamically adjusts the time constants by deriving an index of the extent to which said conductance has changed suddenly, and changes said time constants in an opposite sense to a corresponding change in said index.
17. Apparatus as claimed in claim 16 , wherein said processor means drives said index from said calculated respiratory airflow by determining the extent to which the absolute magnitude of calculated airflow is larger than expected for longer than expected.
18. A computer program for determining instantaneous respiratory airflow for a subject receiving breathable gas by a mask and in the presence of any mask leak, the program receiving input data of instantaneous airflow and pressure at the mask, and comprising the computational steps of:
a) determining instantaneous airflow at the mask;
b) determining instantaneous pressure at the mask;
c) estimating non-linear conductance of said leak path as the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure;
d) determining instantaneous leak flow to be said conductance multiplied by the square root of the said instantaneous pressure; and
e) calculating the respiratory airflow as the instantaneous airflow minus the instantaneous leak flow.
19. A method for determining whether a leak flow at a mask of a patient undergoing mechanical ventilation has suddenly changed, the method comprising:
determining a respiratory airflow of the patient; and
determining whether the absolute magnitude of the respiratory airflow is larger than expected for longer than expected.
20. A method as claimed in claim 19 , wherein the determining whether the absolute magnitude of the respiratory airflow is larger than expected for longer than expected comprises determining whether at least one of the following conditions hold:
the respiratory airflow during inspiration is large positive for a time that is large compared with an expected duration of a normal inspiration, and
the respiratory airflow during expiration is large negative for a time that is large compared with an expected duration of a normal expiration.
21. A method as claimed in claim 19 , wherein the determining whether the leak flow at the mask has suddenly changed comprises determining an index J of an extent to which the leak flow at the mask has suddenly changed.
22. A method as claimed in claim 21 , wherein the determining the index J comprises determining an instantaneous index I of an extent to which the absolute magnitude of the respiratory airflow is larger than expected for longer than expected.
23. A method as claimed in claim 22 , further comprising passing the instantaneous index I through a peak detector followed by a low pass filter.
24. A method as claimed in claim 22 , wherein the determining the instantaneous index I comprises:
determining an instantaneous index II of an extent to which the respiratory airflow during inspiration is large positive for a time that is large compared with an expected duration of a normal inspiration,
determining an instantaneous index IE of an extent to which the respiratory airflow during expiration is large negative for a time that is large compared with an expected duration of a normal expiration, and
determining the larger of the instantaneous index II and the instantaneous index IE.
25. A method as claimed in claim 24 , wherein the determining the instantaneous index II comprises:
determining an extent AI to which the respiratory airflow during inspiration is positive for a time that is large compared with the expected duration of a normal inspiration,
determining an extent BI to which the respiratory airflow during inspiration is large and positive, and
determining the lesser of the extent AI and the extent BI.
26. A method as claimed in claim 24 , wherein the determining the instantaneous index IE comprises:
determining an extent AE to which the respiratory airflow during expiration is negative for a time that is large compared with the expected duration of a normal expiration,
determining an extent BE to which the respiratory airflow during expiration is large and negative, and
determining the lesser of the extent AE and the extent BE.
27. A method as claimed in claim 19 , whereby the determining the respiratory airflow comprises:
measuring airflow in a gas delivery circuit coupled to the mask;
calculating an instantaneous pressure at the mask;
determining an instantaneous leak flow at the mask from the calculated instantaneous pressure at the mask; and
calculating respiratory airflow as the measured delivery circuit airflow minus the instantaneous leak flow.
28. A method as claimed in claim 27 , wherein the calculating the instantaneous pressure at the mask comprises:
measuring a pressure in the gas delivery circuit coupled to the mask;
calculating a pressure drop along the delivery circuit to the mask as a function of the measured delivery circuit airflow; and
calculating the instantaneous pressure at the mask as the measured delivery circuit pressure less the pressure drop.
29. A method as claimed in claim 27 , wherein the determining the instantaneous leak flow at the mask comprises:
estimating a leak conductance; and
multiplying the estimated leak conductance by the square root of the instantaneous pressure at the mask.
30. A method as claimed in claim 29 , wherein the estimating the leak conductance comprises:
determining an instantaneous airflow at the mask; and
estimating the leak conductance by:
low pass filtering the determined instantaneous airflow at the mask, and
dividing by a low pass filtered square root of the instantaneous pressure at the mask.
31. A method as claimed in claim 30 , wherein determining the instantaneous airflow at the mask comprises:
computing an exhaust flow as a function of the instantaneous pressure at the mask; and
subtracting the exhaust flow from the measured delivery circuit airflow.
32. A method as claimed in claim 30 , whereby time constants for the low pass filtering are dynamically adjustable dependent upon whether the leak flow has suddenly changed.
33. A method as claimed in claim 32 , whereby said dynamic adjustment comprises:
deriving an index of an extent to which the leak flow at the mask has suddenly changed; and
changing said time constants in an opposite sense to a corresponding change in the index.
34. Apparatus for determining whether a leak flow at a mask of a patient undergoing mechanical ventilation has suddenly changed, the apparatus comprising:
transducer means located at or proximate the mask to determine a respiratory airflow of the patient; and
a processor configured to determine whether the absolute magnitude of the respiratory airflow is larger than expected for longer than expected.
35. Apparatus as claimed in claim 34 , wherein said transducer means comprises a pneumotachograph coupled to a differential pressure transducer.
36. Apparatus as claimed in claim 35 , wherein said pneumotachograph is located between the mask and a mask exhaust.
37. Apparatus as claimed in claim 34 , wherein said transducer means is located in a gas delivery circuit connected with said mask and remote from said mask.
38. Apparatus for providing continuous positive airway pressure treatment or mechanical ventilation, the apparatus comprising:
a turbine for generation of a supply of breathable gas;
a gas delivery tube having connection with the turbine;
a mask having connection to the delivery tube to supply said breathable gas to a patient's airway, the mask having a leak path;
transducer means located at or proximate the mask to determine a respiratory airflow of the patient;
a processor configured to determine whether the absolute magnitude of the respiratory airflow is larger than expected for longer than expected; and
control means to control the flow generator to control an instantaneous mask pressure on the basis of the determination.
39. A computer readable storage medium storing a computer program comprising instructions configured to cause a processor to carry out a method of determining whether a leak flow at a mask of a patient undergoing mechanical ventilation has suddenly changed, the method comprising:
determining a respiratory airflow of the patient; and
determining whether the absolute magnitude of the respiratory airflow is larger than expected for longer than expected.
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US09/902,011 US6659101B2 (en) | 1996-08-14 | 2001-07-10 | Determination of leak and respiratory airflow |
US10/726,114 US6945248B2 (en) | 1996-08-14 | 2003-12-01 | Determination of leak and respiratory airflow |
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US09/902,011 Expired - Lifetime US6659101B2 (en) | 1996-08-14 | 2001-07-10 | Determination of leak and respiratory airflow |
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US12/649,877 Expired - Fee Related US8763609B2 (en) | 1996-08-14 | 2009-12-30 | Determination of leak and respiratory airflow |
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AT (1) | ATE342083T1 (en) |
AU (2) | AUPO163896A0 (en) |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130255682A1 (en) * | 2012-03-30 | 2013-10-03 | Nellcor Puritan Bennett Llc | Methods and systems for compensation of tubing related loss effects |
Families Citing this family (152)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5632269A (en) | 1989-09-22 | 1997-05-27 | Respironics Inc. | Breathing gas delivery method and apparatus |
US6000396A (en) * | 1995-08-17 | 1999-12-14 | University Of Florida | Hybrid microprocessor controlled ventilator unit |
AU2002306200B2 (en) * | 1996-08-14 | 2004-12-23 | Resmed Limited | Determination of Leak and Respiratory Airflow |
AUPO163896A0 (en) * | 1996-08-14 | 1996-09-05 | Resmed Limited | Determination of respiratory airflow |
AUPO247496A0 (en) | 1996-09-23 | 1996-10-17 | Resmed Limited | Assisted ventilation to match patient respiratory need |
AUPO301796A0 (en) | 1996-10-16 | 1996-11-07 | Resmed Limited | A vent valve apparatus |
US5881717A (en) * | 1997-03-14 | 1999-03-16 | Nellcor Puritan Bennett Incorporated | System and method for adjustable disconnection sensitivity for disconnection and occlusion detection in a patient ventilator |
SE9704643D0 (en) * | 1997-12-12 | 1997-12-12 | Astra Ab | Inhalation apparatus and method |
AUPP693398A0 (en) * | 1998-11-05 | 1998-12-03 | Resmed Limited | Fault diagnosis in CPAP and NIPPV devices |
AUPP783198A0 (en) | 1998-12-21 | 1999-01-21 | Resmed Limited | Determination of mask fitting pressure and correct mask fit |
US6467477B1 (en) * | 1999-03-26 | 2002-10-22 | Respironics, Inc. | Breath-based control of a therapeutic treatment |
US6758216B1 (en) * | 1999-09-15 | 2004-07-06 | Resmed Limited | Ventilatory assistance using an external effort sensor |
US6910480B1 (en) * | 1999-09-15 | 2005-06-28 | Resmed Ltd. | Patient-ventilator synchronization using dual phase sensors |
DE60032929T2 (en) * | 1999-09-15 | 2007-10-25 | ResMed Ltd., Bella Vista | SYNCHRONIZING A VENTILATION DEVICE THROUGH DOUBLE PHASE SENSORS |
US6553992B1 (en) | 2000-03-03 | 2003-04-29 | Resmed Ltd. | Adjustment of ventilator pressure-time profile to balance comfort and effectiveness |
US6532956B2 (en) * | 2000-03-30 | 2003-03-18 | Respironics, Inc. | Parameter variation for proportional assist ventilation or proportional positive airway pressure support devices |
DE10021581B4 (en) * | 2000-04-27 | 2005-01-13 | Auergesellschaft Gmbh | Volume control for fan filter units |
CA2421808C (en) | 2000-09-28 | 2009-12-15 | Invacare Corporation | Carbon dioxide-based bi-level cpap control |
US6644310B1 (en) * | 2000-09-29 | 2003-11-11 | Mallinckrodt Inc. | Apparatus and method for providing a breathing gas employing a bi-level flow generator with an AC synchronous motor |
US6546930B1 (en) | 2000-09-29 | 2003-04-15 | Mallinckrodt Inc. | Bi-level flow generator with manual standard leak adjustment |
JP4348082B2 (en) * | 2000-12-11 | 2009-10-21 | レスメド・リミテッド | Device for judging the patient's situation after stroke onset |
JP4336496B2 (en) * | 2000-12-29 | 2009-09-30 | レスメド・リミテッド | Characterizing the mask system |
AUPR315401A0 (en) | 2001-02-16 | 2001-03-15 | Resmed Limited | An apparatus for supplying clean breathable gas |
DE10161057A1 (en) * | 2001-12-12 | 2003-07-10 | Heptec Gmbh | Process for controlling the differential pressure in a CPAP device and CPAP device |
DE10200183A1 (en) * | 2002-01-04 | 2003-07-17 | Heptec Gmbh | Method for determining the mask pressure of a CPAP (continuous positive airway pressure) breathing device to enable its pressure regulation, whereby a theoretical pressure is determined to which a correction pressure is applied |
US7448383B2 (en) * | 2002-03-08 | 2008-11-11 | Kaerys, S.A. | Air assistance apparatus providing fast rise and fall of pressure within one patient's breath |
US7438073B2 (en) * | 2002-03-08 | 2008-10-21 | Kaerys S.A. | Air assistance apparatus for computing the airflow provided by only means of pressure sensors |
US7000611B2 (en) | 2002-03-26 | 2006-02-21 | Klemperer Walter G | Mouthpiece, nasal seal, head appliance, apparatus, and methods of treating sleep apnea |
CA2386639A1 (en) * | 2002-05-16 | 2003-11-16 | Dynamic Mt Gmbh | Portable electronic spirometer |
EP1605999A1 (en) * | 2003-03-24 | 2005-12-21 | Weinmann Geräte für Medizin GmbH & Co. KG | Method and device for detecting leaks in respiratory gas supply systems |
EP1477199A1 (en) * | 2003-05-15 | 2004-11-17 | Azienda Ospedaliera Pisana | Apparatus for non-invasive mechanical ventilation |
US7152598B2 (en) * | 2003-06-23 | 2006-12-26 | Invacare Corporation | System and method for providing a breathing gas |
US7621270B2 (en) * | 2003-06-23 | 2009-11-24 | Invacare Corp. | System and method for providing a breathing gas |
US7435236B2 (en) | 2003-06-27 | 2008-10-14 | Navilyst Medical, Inc. | Pressure actuated valve with improved biasing member |
US7114497B2 (en) * | 2003-07-18 | 2006-10-03 | Acoba, Llc | Method and system of individually controlling airway pressure of a patient's nares |
US8118024B2 (en) | 2003-08-04 | 2012-02-21 | Carefusion 203, Inc. | Mechanical ventilation system utilizing bias valve |
US7527053B2 (en) | 2003-08-04 | 2009-05-05 | Cardinal Health 203, Inc. | Method and apparatus for attenuating compressor noise |
BRPI0413275A (en) | 2003-08-04 | 2006-10-10 | Pulmonetic Systems Inc | portable fan and portable fan system |
US8156937B2 (en) | 2003-08-04 | 2012-04-17 | Carefusion 203, Inc. | Portable ventilator system |
US7607437B2 (en) | 2003-08-04 | 2009-10-27 | Cardinal Health 203, Inc. | Compressor control system and method for a portable ventilator |
US7252652B2 (en) | 2003-08-29 | 2007-08-07 | Boston Scientific Scimed, Inc. | Valved catheters including high flow rate catheters |
CA2443510C (en) * | 2003-09-30 | 2010-09-14 | Scott Technologies, Inc. | Automatic transfer regulator for hose-line respirator |
WO2005037355A1 (en) | 2003-10-17 | 2005-04-28 | Resmed Limited | Methods and apparatus for heart failure treatment |
US8584676B2 (en) * | 2003-11-19 | 2013-11-19 | Immediate Response Technologies | Breath responsive filter blower respirator system |
DE602004028039D1 (en) | 2003-11-26 | 2010-08-19 | Resmed Ltd | DEVICE FOR THE SYSTEMIC CONTROL OF AIR SUPPLY IN THE EVENT OF AIR RESPONSIBILITY |
CN101804232B (en) * | 2003-12-29 | 2013-09-04 | 雷斯梅德有限公司 | Mechanical ventilation in presence of sleep disordered breathing |
US9314608B2 (en) | 2004-01-29 | 2016-04-19 | Angiodynamics, Inc | Pressure activated safety valve with high flow slit |
US7878198B2 (en) | 2004-03-31 | 2011-02-01 | Michael Farrell | Methods and apparatus for monitoring the cardiovascular condition of patients with sleep disordered breathing |
US20060005834A1 (en) * | 2004-07-07 | 2006-01-12 | Acoba, Llc | Method and system of providing therapeutic gas to a patient to prevent breathing airway collapse |
CN102961812B (en) | 2004-08-10 | 2016-12-21 | 瑞思迈有限公司 | The method and apparatus of humidification of breathable gas with profiled delivery |
DE102004040659A1 (en) * | 2004-08-20 | 2006-02-23 | Weinmann Geräte für Medizin GmbH + Co. KG | Apparatus for ventilation and method for controlling a ventilator |
US7717110B2 (en) * | 2004-10-01 | 2010-05-18 | Ric Investments, Llc | Method and apparatus for treating Cheyne-Stokes respiration |
CN101043913B (en) | 2004-10-20 | 2012-02-08 | 雷斯梅德有限公司 | Method and apparatus for detecting ineffective inspiratory efforts and improving patient-ventilator interaction |
US7984712B2 (en) * | 2004-10-25 | 2011-07-26 | Bird Products Corporation | Patient circuit disconnect system for a ventilator and method of detecting patient circuit disconnect |
US20060096596A1 (en) * | 2004-11-05 | 2006-05-11 | Occhialini James M | Wearable system for positive airway pressure therapy |
US20060174885A1 (en) * | 2005-02-08 | 2006-08-10 | Acoba, Llc | Method and related system to control applied pressure in CPAP systems |
JP5356808B2 (en) * | 2005-06-14 | 2013-12-04 | レスメド・リミテッド | Method and apparatus for controlling mask leakage in CPAP treatment |
US20100024819A1 (en) * | 2005-06-21 | 2010-02-04 | Breas Medical Ab | Apparatus, method, system and computer program for leakage compensation for a ventilator |
EP1948276B1 (en) | 2005-10-21 | 2019-01-02 | ResMed Limited | Method and apparatus for improving flow and pressure estimation in cpap systems |
US8172766B1 (en) * | 2005-11-04 | 2012-05-08 | Cleveland Medical Devices Inc. | Integrated sleep diagnosis and treatment device and method |
US7942824B1 (en) | 2005-11-04 | 2011-05-17 | Cleveland Medical Devices Inc. | Integrated sleep diagnostic and therapeutic system and method |
US20070113847A1 (en) * | 2005-11-22 | 2007-05-24 | General Electric Company | Respiratory monitoring with cannula receiving first respiratory airflows and second respiratory airflows |
US20070113850A1 (en) * | 2005-11-22 | 2007-05-24 | General Electric Company | Respiratory monitoring with cannula receiving respiratory airflows and differential pressure transducer |
US7422015B2 (en) * | 2005-11-22 | 2008-09-09 | The General Electric Company | Arrangement and method for detecting spontaneous respiratory effort of a patient |
US20080078393A1 (en) * | 2005-11-22 | 2008-04-03 | General Electric Company | Respiratory monitoring with cannula receiving respiratory airflows, differential pressure transducer, and ventilator |
US20070113856A1 (en) * | 2005-11-22 | 2007-05-24 | General Electric Company | Respiratory monitoring with cannula receiving respiratory airflows |
US20070113848A1 (en) * | 2005-11-22 | 2007-05-24 | General Electric Company | Respiratory monitoring with cannula receiving respiratory airflows and exhaled gases |
EP1960025B1 (en) * | 2005-12-16 | 2018-12-19 | Hamilton Medical AG | Flexible conduit system for respiratory devices |
DE102005061439B3 (en) * | 2005-12-22 | 2007-05-16 | Draeger Medical Ag | Determination of leakage in respiration apparatus uses pressure sensor to measure initial inspiration pressure, pressure being altered during subsequent inspirations and leakage volume calculated |
US7694677B2 (en) * | 2006-01-26 | 2010-04-13 | Nellcor Puritan Bennett Llc | Noise suppression for an assisted breathing device |
US7509957B2 (en) * | 2006-02-21 | 2009-03-31 | Viasys Manufacturing, Inc. | Hardware configuration for pressure driver |
US7747319B2 (en) * | 2006-03-17 | 2010-06-29 | Zoll Medical Corporation | Automated resuscitation device with ventilation sensing and prompting |
US7762006B2 (en) * | 2006-06-14 | 2010-07-27 | Siestamed, Technologies | Medical equipment drying device |
EP2789359A3 (en) * | 2006-08-30 | 2014-12-24 | ResMed Ltd. | Determination of leak during CPAP treatment |
US20090320842A1 (en) * | 2006-09-07 | 2009-12-31 | Renee Frances Doherty | Mask and flow generator system |
UY30892A1 (en) * | 2007-02-07 | 2008-09-02 | Smithkline Beckman Corp | AKT ACTIVITY INHIBITORS |
US20080251079A1 (en) * | 2007-04-13 | 2008-10-16 | Invacare Corporation | Apparatus and method for providing positive airway pressure |
DE102007033860A1 (en) * | 2007-07-20 | 2009-01-22 | Boehringer Ingelheim Pharma Gmbh & Co. Kg | Test arrangement for testing sealing between mouthpiece of inhaler and user's lips has channel for secondary air around user's lips with second flow measurement device |
CA2733809C (en) * | 2007-08-22 | 2017-09-19 | The Research Foundation Of State University Of New York | Breathing-gas delivery and sharing system and method |
CA2696773A1 (en) | 2007-08-23 | 2009-02-26 | Invacare Corporation | Method and apparatus for adjusting desired pressure in positive airway pressure devices |
US20090078258A1 (en) * | 2007-09-21 | 2009-03-26 | Bowman Bruce R | Pressure regulation methods for positive pressure respiratory therapy |
US20090078255A1 (en) * | 2007-09-21 | 2009-03-26 | Bowman Bruce R | Methods for pressure regulation in positive pressure respiratory therapy |
US7975691B2 (en) * | 2007-10-23 | 2011-07-12 | Eun Jong Cha | Continuous positive airway pressure device by controlling the pressure in the face mask |
US7800360B2 (en) * | 2007-10-31 | 2010-09-21 | Sony Ericsson Mobile Communications Ab | Connector system with magnetic audio volume control and method |
US7997885B2 (en) | 2007-12-03 | 2011-08-16 | Carefusion 303, Inc. | Roots-type blower reduced acoustic signature method and apparatus |
US9078966B2 (en) | 2007-12-07 | 2015-07-14 | Liebel-Flarsheim Company Llc | Push to install syringe mount for powered injector systems |
US8746248B2 (en) | 2008-03-31 | 2014-06-10 | Covidien Lp | Determination of patient circuit disconnect in leak-compensated ventilatory support |
US8272379B2 (en) | 2008-03-31 | 2012-09-25 | Nellcor Puritan Bennett, Llc | Leak-compensated flow triggering and cycling in medical ventilators |
US8267085B2 (en) | 2009-03-20 | 2012-09-18 | Nellcor Puritan Bennett Llc | Leak-compensated proportional assist ventilation |
EP2313138B1 (en) | 2008-03-31 | 2018-09-12 | Covidien LP | System and method for determining ventilator leakage during stable periods within a breath |
US8888711B2 (en) | 2008-04-08 | 2014-11-18 | Carefusion 203, Inc. | Flow sensor |
US8257321B2 (en) | 2008-05-21 | 2012-09-04 | Navilyst Medical, Inc. | Pressure activated valve for high flow rate and pressure venous access applications |
GB2460629B (en) * | 2008-05-28 | 2011-03-30 | Plant Test Services Ltd | Leak detector |
WO2009149357A1 (en) | 2008-06-06 | 2009-12-10 | Nellcor Puritan Bennett Llc | Systems and methods for ventilation in proportion to patient effort |
US20100071696A1 (en) * | 2008-09-25 | 2010-03-25 | Nellcor Puritan Bennett Llc | Model-predictive online identification of patient respiratory effort dynamics in medical ventilators |
EP2168623B1 (en) | 2008-09-26 | 2011-09-21 | General Electric Company | Arrangement for detecting a leak in anesthesia system |
US8083721B2 (en) | 2009-01-29 | 2011-12-27 | Navilyst Medical, Inc. | Power injection valve |
FR2941625B1 (en) * | 2009-02-05 | 2012-05-18 | Materiels Ind Securite | COMBINATION FOR PROTECTING A PERSON AND CORRESPONDING ASSEMBLY |
US8424521B2 (en) | 2009-02-27 | 2013-04-23 | Covidien Lp | Leak-compensated respiratory mechanics estimation in medical ventilators |
US8418691B2 (en) | 2009-03-20 | 2013-04-16 | Covidien Lp | Leak-compensated pressure regulated volume control ventilation |
US8007468B2 (en) | 2009-07-13 | 2011-08-30 | Navilyst Medical, Inc. | Method to secure an elastic component in a valve |
CN102665546B (en) | 2009-07-16 | 2015-12-09 | 瑞思迈有限公司 | The detection of sleep state |
US8419597B2 (en) * | 2009-08-17 | 2013-04-16 | Emily L. Cooper | Systems and methods for a hill training apparatus for a bicycle trainer |
GB2474917B (en) * | 2009-11-02 | 2015-12-23 | Scott Health & Safety Ltd | Improvements to powered air breathing apparatus |
CN101806652B (en) * | 2010-02-02 | 2011-11-09 | 清华大学 | System and method for detecting pipe breakage of steam generator of high temperature gas-cooled reactor |
US8707952B2 (en) | 2010-02-10 | 2014-04-29 | Covidien Lp | Leak determination in a breathing assistance system |
EP2368593A1 (en) * | 2010-03-26 | 2011-09-28 | Dräger Medical GmbH | Estimating a leakage flow |
EP2590702B1 (en) * | 2010-07-09 | 2014-05-14 | Koninklijke Philips N.V. | Leak estimation using leak model identification |
US9272111B2 (en) | 2010-07-27 | 2016-03-01 | Koninklijke Philips N.V. | Leak estimation using function estimation |
EP2598192B1 (en) * | 2010-07-30 | 2018-04-04 | ResMed Limited | Methods and devices with leak detection |
CN103189088B (en) * | 2010-10-26 | 2016-12-07 | 皇家飞利浦电子股份有限公司 | Pressure line for mechanical ventilating machine purges system |
US10561339B2 (en) * | 2010-12-21 | 2020-02-18 | Koninklijke Philips N.V. | System and method for determining carbon dioxide excreted during non-invasive ventilation |
CN102641536A (en) * | 2011-02-17 | 2012-08-22 | 新利虹科技股份有限公司 | Positive pressure breathing device and air leakage quantity obtaining method of positive pressure breathing device |
US8783250B2 (en) | 2011-02-27 | 2014-07-22 | Covidien Lp | Methods and systems for transitory ventilation support |
CN103501848A (en) * | 2011-03-25 | 2014-01-08 | 因斯利普科技有限公司 | Breathing apparatus |
US8714154B2 (en) | 2011-03-30 | 2014-05-06 | Covidien Lp | Systems and methods for automatic adjustment of ventilator settings |
US8776792B2 (en) | 2011-04-29 | 2014-07-15 | Covidien Lp | Methods and systems for volume-targeted minimum pressure-control ventilation |
EP2756279B1 (en) * | 2011-09-13 | 2018-11-14 | Koninklijke Philips N.V. | Pressure based gas leak testing |
JP6329902B2 (en) | 2011-09-13 | 2018-05-23 | レスメド・リミテッドResMed Limited | Respirator vent device |
US9498589B2 (en) | 2011-12-31 | 2016-11-22 | Covidien Lp | Methods and systems for adaptive base flow and leak compensation |
US10362967B2 (en) | 2012-07-09 | 2019-07-30 | Covidien Lp | Systems and methods for missed breath detection and indication |
US9895524B2 (en) | 2012-07-13 | 2018-02-20 | Angiodynamics, Inc. | Fluid bypass device for valved catheters |
US10076619B2 (en) | 2012-09-11 | 2018-09-18 | Resmed Limited | Vent arrangement for respiratory mask |
US10010691B2 (en) * | 2012-10-31 | 2018-07-03 | Maquet Critical Care Ab | Breathing apparatus and method for detecting leakage in a sampling line |
WO2014138803A1 (en) | 2013-03-14 | 2014-09-18 | Resmed Limited | Vent arrangement for respiratory device |
US10328222B2 (en) | 2013-03-14 | 2019-06-25 | ResMed Pty Ltd | Vent device for use with a respiratory device |
WO2014142682A1 (en) * | 2013-03-15 | 2014-09-18 | Fisher & Paykel Healthcare Limited | A respiratory assistance device and a method of controlling said device |
GB201306067D0 (en) * | 2013-04-04 | 2013-05-22 | Smiths Medical Int Ltd | Resuscitator arrangements and flow monitoring |
WO2014203104A1 (en) * | 2013-06-19 | 2014-12-24 | Koninklijke Philips N.V. | Determining of subject zero flow using cluster analysis |
USD737953S1 (en) | 2013-07-26 | 2015-09-01 | Resmed Limited | Patient interface |
EP3033130B1 (en) * | 2013-08-12 | 2017-10-11 | Koninklijke Philips N.V. | Detecting the fit of a patient interface device |
US9675771B2 (en) | 2013-10-18 | 2017-06-13 | Covidien Lp | Methods and systems for leak estimation |
US20150320961A1 (en) * | 2014-05-07 | 2015-11-12 | Oridion Medical 1987 Ltd. | Airway access device |
US9808591B2 (en) | 2014-08-15 | 2017-11-07 | Covidien Lp | Methods and systems for breath delivery synchronization |
US10576240B2 (en) | 2014-10-24 | 2020-03-03 | Koninklijke Philips N.V. | System and method for controlling leak |
US9950129B2 (en) | 2014-10-27 | 2018-04-24 | Covidien Lp | Ventilation triggering using change-point detection |
CN106999740B (en) | 2014-12-04 | 2021-11-26 | 瑞思迈私人有限公司 | Wearable device for delivering air |
CN107530514B (en) * | 2015-03-20 | 2020-08-11 | 瑞思迈私人有限公司 | Method and apparatus for ventilation treatment of respiratory disorders |
EP3319672A1 (en) * | 2015-07-07 | 2018-05-16 | Koninklijke Philips N.V. | Methods and systems for patient airway and leak flow estimation for non-invasive ventilation |
NZ772572A (en) * | 2015-08-14 | 2023-02-24 | ResMed Pty Ltd | Monitoring respiratory pressure therapy |
US11266801B2 (en) | 2015-10-09 | 2022-03-08 | University Of Utah Research Foundation | Ventilation devices and systems and methods of using same |
US10271788B2 (en) * | 2016-02-26 | 2019-04-30 | MGC Diagnostics Corp. | Apparatus and method for measuring energy expenditure using indirect calorimetry |
US10610678B2 (en) | 2016-08-11 | 2020-04-07 | Angiodynamics, Inc. | Bi-directional, pressure-actuated medical valve with improved fluid flow control and method of using such |
US11389608B2 (en) | 2016-09-19 | 2022-07-19 | Koninklijke Philips N.V. | Methods and systems for patient airway and leak flow estimation for non-invasive ventilation |
EP3740269B1 (en) | 2018-01-17 | 2024-04-10 | ZOLL Medical Corporation | System to assist a rescuer with an intubation procedure for a patient |
EP3793656A1 (en) | 2018-05-14 | 2021-03-24 | Covidien LP | Systems and methods for respiratory effort detection utilizing signal distortion |
US11752287B2 (en) | 2018-10-03 | 2023-09-12 | Covidien Lp | Systems and methods for automatic cycling or cycling detection |
US11906097B2 (en) * | 2019-09-04 | 2024-02-20 | Vyaire Medical, Inc. | Ventilation leak component |
CN112870515B (en) * | 2019-11-29 | 2023-01-31 | 深圳市大雅医疗技术有限公司 | Mask type parameter adjusting method, breathing assistance device and storage medium |
CN112999478A (en) * | 2019-12-20 | 2021-06-22 | 广州和普乐健康科技有限公司 | Adaptive tidal volume calculation method and device and breathing machine |
CN110975090A (en) * | 2019-12-20 | 2020-04-10 | 广州和普乐健康科技有限公司 | Breathing machine air leakage calculation method and device, storage medium and computer equipment |
AU2021230446B2 (en) | 2020-03-06 | 2023-08-10 | Resmed Sensor Technologies Limited | Systems and methods for detecting an intentional leak characteristic curve for a respiratory therapy system |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3961627A (en) * | 1973-09-07 | 1976-06-08 | Hoffmann-La Roche Inc. | Automatic regulation of respirators |
US4671297A (en) * | 1985-10-25 | 1987-06-09 | Schulze Jr Karl F | Method and apparatus for monitoring infants on assisted ventilation |
US5129390A (en) * | 1987-12-18 | 1992-07-14 | Institut Nationale De La Sante Et De La Recherche Medicale | Process for regulating an artificial ventilation device and such device |
US5347843A (en) * | 1992-09-23 | 1994-09-20 | Korr Medical Technologies Inc. | Differential pressure flowmeter with enhanced signal processing for respiratory flow measurement |
US5551419A (en) * | 1994-12-15 | 1996-09-03 | Devilbiss Health Care, Inc. | Control for CPAP apparatus |
US5619986A (en) * | 1991-01-03 | 1997-04-15 | Olof Werner | Method and apparatus for controlling the concentration of at least one component in a gas mixture in an anaesthetic system |
Family Cites Families (240)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US35339A (en) * | 1862-05-20 | Improvement in tips for fishing-rods | ||
DE459104C (en) | 1928-04-26 | Hans Jancke | Device for preventing snoring | |
US35295A (en) * | 1862-05-20 | Improvement in water-elevators | ||
US2904033A (en) * | 1957-03-04 | 1959-09-15 | Sylvan M Shane | Breathing indicator |
US3099985A (en) * | 1960-12-21 | 1963-08-06 | Porter C Wilson | Resuscitator |
SE331590B (en) | 1967-04-04 | 1971-01-04 | Elema Schoenander Ab | |
US3559638A (en) * | 1967-09-19 | 1971-02-02 | James A Potter | Respiration meter having several modes of operation |
US3611801A (en) * | 1968-10-28 | 1971-10-12 | Nasa | Respiration monitor |
US3595228A (en) * | 1968-11-27 | 1971-07-27 | Robert C Simon | Flow line break alarm device |
US3802417A (en) * | 1968-12-21 | 1974-04-09 | V Lang | Device for combined monitoring and stimulation of respiration |
US3989037A (en) * | 1970-06-23 | 1976-11-02 | Siemens Aktiengesellschaft | Flow measuring device |
US3741208A (en) * | 1971-02-23 | 1973-06-26 | B Jonsson | Lung ventilator |
US3726270A (en) | 1971-09-20 | 1973-04-10 | Syst Res Labor Inc | Pulmonary information transmission system |
BE791878A (en) * | 1971-11-26 | 1973-03-16 | Bryan Donkin Co Ltd | CHECK VALVE IMPROVEMENT |
US3914994A (en) * | 1971-12-15 | 1975-10-28 | Philip M Banner | Liquid flow indicating and flow control means |
CH549392A (en) | 1972-03-27 | 1974-05-31 | Hoffmann La Roche | VENTILATION DEVICE WITH AUTOMATIC REGULATION OF PRESSURE AND FLOW OF BREATHING GAS. |
US3817246A (en) * | 1972-12-11 | 1974-06-18 | Puritan Bennett Corp | Flow responsive respiration apparatus |
IE39702B1 (en) | 1973-05-10 | 1978-12-06 | Klenk A | Back-flow and odour trap for liquids |
US3882847A (en) * | 1973-12-11 | 1975-05-13 | Harvey Barry Jacobs | Low-Cost Pneumatic Apnea or Respiration Monitor |
US3903875A (en) * | 1974-01-24 | 1975-09-09 | Sandoz Ag | Automatically calibrated respiratory ventilation monitor |
US3903881A (en) * | 1974-04-12 | 1975-09-09 | Bourns Inc | Respirator system and method |
US3932054A (en) * | 1974-07-17 | 1976-01-13 | Western Engineering & Mfg. Co. | Variable pitch axial fan |
US3992598A (en) * | 1974-12-04 | 1976-11-16 | Afton Incorporated | Airflow velocity switch |
US3985467A (en) * | 1975-05-27 | 1976-10-12 | Milton Roy Company | Constant pressure pump |
DE2537765B2 (en) | 1975-08-25 | 1981-04-09 | Siemens AG, 1000 Berlin und 8000 München | Medical inhalation device for the treatment of diseases of the respiratory tract |
US4006634A (en) * | 1975-09-17 | 1977-02-08 | National Semiconductor Corporation | Flow meter |
US3995661A (en) * | 1975-09-22 | 1976-12-07 | Wheelabrator-Frye, Inc. | Flow control valve for magnetic particulate |
GB1576118A (en) | 1976-06-02 | 1980-10-01 | Boc Ltd | Lung ventilators |
US4083245A (en) * | 1977-03-21 | 1978-04-11 | Research Development Corporation | Variable orifice gas flow sensing head |
US4109749A (en) * | 1976-11-09 | 1978-08-29 | Minnesota Mining And Manufacturing Company | Muffler |
GB1583273A (en) | 1977-05-06 | 1981-01-21 | Medishield Corp Ltd | Lung ventilators |
US4387722A (en) * | 1978-11-24 | 1983-06-14 | Kearns Kenneth L | Respiration monitor and x-ray triggering apparatus |
US4249527A (en) * | 1979-02-09 | 1981-02-10 | Case Western Reserve University | Continuous positive airway pressure administrating apparatus |
US4320766A (en) * | 1979-03-13 | 1982-03-23 | Instrumentarium Oy | Apparatus in medicine for the monitoring and or recording of the body movements of a person on a bed, for instance of a patient |
US4433693A (en) * | 1979-09-27 | 1984-02-28 | Hochstein Peter A | Method and assembly for monitoring respiration and detecting apnea |
US4301833A (en) * | 1979-10-05 | 1981-11-24 | Donald Iii Robert A | Flow responsive safety valve |
DE3021326A1 (en) | 1980-06-06 | 1981-12-17 | Drägerwerk AG, 2400 Lübeck | DEVICE FOR MEASURING AT LEAST TWO PNEUMATIC LUNG PARAMETERS AND MEASURING METHODS THEREFOR |
DE3023648A1 (en) * | 1980-06-24 | 1982-01-21 | Jaeger, Erich, 8700 Würzburg | DEVICE FOR EXAMINING THE RESPIRATORY RESPIRATORY SENSITIVITY |
US4322594A (en) * | 1980-06-27 | 1982-03-30 | Respiratory Care, Inc. | Temperature control system with alarm and shut down for non-tracking condition of dual thermometers |
US4312235A (en) * | 1980-09-02 | 1982-01-26 | United Technologies Corporation | Sensor and meter for measuring the mass flow of a fluid stream |
US4414982A (en) * | 1980-11-26 | 1983-11-15 | Tritec Industries, Inc. | Apneic event detector and method |
US4449525A (en) * | 1981-02-08 | 1984-05-22 | White Daniel S | Pulmonary resuscitator |
US4396034A (en) * | 1981-02-23 | 1983-08-02 | Cherniak George S | Arcuate swing check valve |
US4381788A (en) * | 1981-02-27 | 1983-05-03 | Douglas David W | Method and apparatus for detecting apnea |
WO1982003548A1 (en) * | 1981-04-24 | 1982-10-28 | Sullivan Colin Edward | Device for treating snoring sickness |
US4481944A (en) | 1981-11-19 | 1984-11-13 | Bunnell Life Systems, Inc. | Apparatus and method for assisting respiration |
US4580575A (en) * | 1982-06-14 | 1986-04-08 | Aequitron Medical, Inc. | Apnea monitoring system |
US4448058A (en) * | 1982-07-02 | 1984-05-15 | Sensormedics Corporation | Respiratory gas analysis instrument having improved volume calibration method and apparatus |
US4550726A (en) * | 1982-07-15 | 1985-11-05 | Mcewen James A | Method and apparatus for detection of breathing gas interruptions |
US4602644A (en) * | 1982-08-18 | 1986-07-29 | Plasmedics, Inc. | Physiological detector and monitor |
EP0104004A1 (en) * | 1982-09-06 | 1984-03-28 | Graham Cameron Grant | Fluid flowmeter and method of measuring flow rate |
US4506666A (en) * | 1982-12-03 | 1985-03-26 | Kircaldie, Randall And Mcnab | Method and apparatus for rectifying obstructive apnea |
US4530334A (en) * | 1982-12-09 | 1985-07-23 | Solex (U.K.) Limited | Air flow metering |
JPS59107399A (en) | 1982-12-13 | 1984-06-21 | リオン株式会社 | Measurement of nasalization level |
US4499914A (en) * | 1983-04-14 | 1985-02-19 | Litton Systems, Inc. | Selector valve for an aircraft on board oxygen generation system with high pressure oxygen backup |
US4576179A (en) * | 1983-05-06 | 1986-03-18 | Manus Eugene A | Respiration and heart rate monitoring apparatus |
US4738266A (en) * | 1983-05-09 | 1988-04-19 | Thatcher John B | Apnoea monitor |
JPS6015134A (en) | 1983-07-07 | 1985-01-25 | Unitika Ltd | Manufacture of piezo-electric and pyroelectric film |
US4655213A (en) * | 1983-10-06 | 1987-04-07 | New York University | Method and apparatus for the treatment of obstructive sleep apnea |
US4579114A (en) * | 1983-10-11 | 1986-04-01 | Wisdom Corporation | Mouth to mouth resuscitation device |
US4860766A (en) * | 1983-11-18 | 1989-08-29 | Respitrace Corp. | Noninvasive method for measuring and monitoring intrapleural pressure in newborns |
IL71468A (en) * | 1984-04-08 | 1988-06-30 | Dan Atlas | Apnea monitoring method and apparatus |
GB2166871A (en) | 1984-09-03 | 1986-05-14 | Vickers Plc | Respiration monitor |
FI76929C (en) | 1984-09-25 | 1989-01-10 | Etelae Haemeen Keuhkovammayhdi | Inhalation dosing device intended for accurate dosing of disposable drugs given for respiratory illness in the examination stage and / or drugs given as a spray during treatment. |
NZ209900A (en) * | 1984-10-16 | 1989-08-29 | Univ Auckland | Automatic inhaler |
EP0185980B1 (en) | 1984-12-27 | 1995-03-01 | Teijin Limited | Oxygen enriching apparatus |
US4595016A (en) * | 1985-01-30 | 1986-06-17 | Mine Safety Appliances Co. | APNEA monitor |
US4971065A (en) * | 1985-02-11 | 1990-11-20 | Pearce Stephen D | Transducer for detecting apnea |
US4686999A (en) * | 1985-04-10 | 1987-08-18 | Tri Fund Research Corporation | Multi-channel ventilation monitor and method |
US4648396A (en) * | 1985-05-03 | 1987-03-10 | Brigham And Women's Hospital | Respiration detector |
FI81500C (en) * | 1985-05-23 | 1990-11-12 | Etelae Haemeen Keuhkovammayhdi | Respiratory Treatment Unit |
US4648407A (en) * | 1985-07-08 | 1987-03-10 | Respitrace Corporation | Method for detecting and differentiating central and obstructive apneas in newborns |
US4587967A (en) | 1985-07-09 | 1986-05-13 | Lifecare Services, Inc. | Oxygen enriched reciprocating piston respirator |
IT1185906B (en) * | 1985-09-13 | 1987-11-18 | Luciano Gattinoni | BIOMEDICAL SYSTEM AND APPARATUS FOR MEASURING WITH PRECISION OF THE PRESSURE AND VOLUME CHANGE VALUES IN THE PATIENT'S LUNGS |
US4870960A (en) * | 1985-10-07 | 1989-10-03 | Litton Systems, Inc. | Backup breathing gas supply for an oxygen concentrator system |
JPS6294175A (en) * | 1985-10-18 | 1987-04-30 | 鳥取大学長 | Respiration synchronous type gas blowing apparatus and method |
US4747403A (en) | 1986-01-27 | 1988-05-31 | Advanced Pulmonary Technologies, Inc. | Multi-frequency jet ventilation technique and apparatus |
US5052400A (en) * | 1986-02-20 | 1991-10-01 | Dietz Henry G | Method and apparatus for using an inhalation sensor for monitoring and for inhalation therapy |
US4773411A (en) * | 1986-05-08 | 1988-09-27 | Downs John B | Method and apparatus for ventilatory therapy |
US4825802A (en) * | 1986-07-24 | 1989-05-02 | Societe Anonyme Drager | Pheumatic alarm for respirator |
US4674492A (en) | 1986-07-25 | 1987-06-23 | Filcon Corporation | Alarm system for respirator apparatus and method of use |
US4803471A (en) * | 1986-10-24 | 1989-02-07 | Hudson Oxygen Therapy Sales Co. | Ventilator monitor and alarm apparatus |
DE3636669C2 (en) * | 1986-10-28 | 2001-08-16 | Siemens Ag | Arrangement for delivering aerosol to a patient's airways and / or lungs |
US5024219A (en) * | 1987-01-12 | 1991-06-18 | Dietz Henry G | Apparatus for inhalation therapy using triggered dose oxygenator employing an optoelectronic inhalation sensor |
GB8704104D0 (en) | 1987-02-21 | 1987-03-25 | Manitoba University Of | Respiratory system load apparatus |
FR2611505B1 (en) * | 1987-03-05 | 1997-01-10 | Air Liquide | METHOD AND DEVICE FOR SUPPLYING RESPIRATORY OXYGEN |
GB8712223D0 (en) | 1987-05-23 | 1987-07-01 | Care R J | Electronic auto flow control |
US4777963A (en) * | 1987-06-18 | 1988-10-18 | Mckenna Kevin | Respiration monitor |
US5199424A (en) | 1987-06-26 | 1993-04-06 | Sullivan Colin E | Device for monitoring breathing during sleep and control of CPAP treatment that is patient controlled |
US5522382A (en) | 1987-06-26 | 1996-06-04 | Rescare Limited | Device and method for treating obstructed breathing having a delay/ramp feature |
US5322057A (en) | 1987-07-08 | 1994-06-21 | Vortran Medical Technology, Inc. | Intermittent signal actuated nebulizer synchronized to operate in the exhalation phase, and its method of use |
US5388571A (en) | 1987-07-17 | 1995-02-14 | Roberts; Josephine A. | Positive-pressure ventilator system with controlled access for nebulizer component servicing |
US4795314A (en) * | 1987-08-24 | 1989-01-03 | Cobe Laboratories, Inc. | Condition responsive pump control utilizing integrated, commanded, and sensed flowrate signals |
US4802485A (en) * | 1987-09-02 | 1989-02-07 | Sentel Technologies, Inc. | Sleep apnea monitor |
US4938212A (en) * | 1987-10-16 | 1990-07-03 | Puritan-Bennett Corporation | Inspiration oxygen saver |
US4838258A (en) * | 1987-10-26 | 1989-06-13 | Gibeck-Dryden Corporation | Gas sampling lumen for breathing system |
US5065756A (en) | 1987-12-22 | 1991-11-19 | New York University | Method and apparatus for the treatment of obstructive sleep apnea |
US4915103A (en) * | 1987-12-23 | 1990-04-10 | N. Visveshwara, M.D., Inc. | Ventilation synchronizer |
FI82808C (en) * | 1987-12-31 | 1991-04-25 | Etelae Haemeen Keuhkovammayhdi | Ultraljudfinfördelningsanordning |
US4856506A (en) * | 1988-01-11 | 1989-08-15 | Jinotti Walter J | Apparatus for mouth-to-mouth resuscitation |
US5170798A (en) * | 1988-02-10 | 1992-12-15 | Sherwood Medical Company | Pulmonary function tester |
US4887607A (en) | 1988-03-16 | 1989-12-19 | Beatty Robert F | Apparatus for and method of spectral analysis enhancement of polygraph examinations |
US5335656A (en) | 1988-04-15 | 1994-08-09 | Salter Laboratories | Method and apparatus for inhalation of treating gas and sampling of exhaled gas for quantitative analysis |
US4823788A (en) * | 1988-04-18 | 1989-04-25 | Smith Richard F M | Demand oxygen controller and respiratory monitor |
GB8809715D0 (en) | 1988-04-25 | 1988-06-02 | Pa Consulting Services | Fluid mass flow & density sensor |
US4870963A (en) * | 1988-05-06 | 1989-10-03 | Carol Bussell | Respiratory aid device |
US4957107A (en) * | 1988-05-10 | 1990-09-18 | Sipin Anatole J | Gas delivery means |
DE3817985A1 (en) | 1988-05-27 | 1989-12-07 | Salvia Werk Gmbh | DEVICE FOR SUPPORTING THE SPONTANEOUS BREATHING OF A PATIENT |
US4972842A (en) * | 1988-06-09 | 1990-11-27 | Vital Signals, Inc. | Method and apparatus for precision monitoring of infants on assisted ventilation |
US5048515A (en) | 1988-11-15 | 1991-09-17 | Sanso David W | Respiratory gas supply apparatus and method |
US4982738A (en) * | 1988-11-30 | 1991-01-08 | Dr. Madaus Gmbh | Diagnostic apnea monitor system |
US5090248A (en) * | 1989-01-23 | 1992-02-25 | The University Of Melbourne | Electronic transducer |
US5105354A (en) * | 1989-01-23 | 1992-04-14 | Nippon Kayaku Kabushiki Kaisha | Method and apparatus for correlating respiration and heartbeat variability |
US4913401A (en) * | 1989-01-26 | 1990-04-03 | Respironics, Inc. | Valve apparatus |
US4989599A (en) * | 1989-01-26 | 1991-02-05 | Puritan-Bennett Corporation | Dual lumen cannula |
US4938210A (en) * | 1989-04-25 | 1990-07-03 | Trudell Medical | Inhalation chamber in ventilator circuit |
US4960118A (en) * | 1989-05-01 | 1990-10-02 | Pennock Bernard E | Method and apparatus for measuring respiratory flow |
US5259373A (en) | 1989-05-19 | 1993-11-09 | Puritan-Bennett Corporation | Inspiratory airway pressure system controlled by the detection and analysis of patient airway sounds |
US5845636A (en) | 1989-05-19 | 1998-12-08 | Puritan Bennett Corporation | Method and apparatus for maintaining patient airway patency |
US5134995A (en) | 1989-05-19 | 1992-08-04 | Puritan-Bennett Corporation | Inspiratory airway pressure system with admittance determining apparatus and method |
US5107831A (en) | 1989-06-19 | 1992-04-28 | Bear Medical Systems, Inc. | Ventilator control system using sensed inspiratory flow rate |
US5239995A (en) | 1989-09-22 | 1993-08-31 | Respironics, Inc. | Sleep apnea treatment apparatus |
US5632269A (en) | 1989-09-22 | 1997-05-27 | Respironics Inc. | Breathing gas delivery method and apparatus |
US5148802B1 (en) * | 1989-09-22 | 1997-08-12 | Respironics Inc | Method and apparatus for maintaining airway patency to treat sleep apnea and other disorders |
USRE35295E (en) | 1989-09-22 | 1996-07-16 | Respironics, Inc. | Sleep apnea treatment apparatus |
US5009635A (en) * | 1989-11-06 | 1991-04-23 | Respironics Inc. | Pump apparatus |
US5165398A (en) | 1989-12-08 | 1992-11-24 | Bird F M | Ventilator and oscillator for use therewith and method |
US5231983A (en) | 1990-01-03 | 1993-08-03 | Minnesota Mining And Manufacturing | Method of and apparatus for the aerosol administration of medication |
US5448996A (en) | 1990-02-02 | 1995-09-12 | Lifesigns, Inc. | Patient monitor sheets |
SE466188B (en) * | 1990-02-16 | 1992-01-13 | Hoek Instr Ab | ACOUSTIC RESPIRATORY DETECTOR |
CA2011609C (en) | 1990-03-06 | 1998-09-15 | William Edward Price | Resuscitation and inhalation device |
DE69128225T2 (en) | 1990-03-09 | 1998-03-19 | Matsushita Electric Ind Co Ltd | DEVICE FOR INDICATING SLEEP |
US5161525A (en) | 1990-05-11 | 1992-11-10 | Puritan-Bennett Corporation | System and method for flow triggering of pressure supported ventilation |
US5046491A (en) | 1990-03-27 | 1991-09-10 | Derrick Steven J | Apparatus and method for respired gas collection and analysis |
JP2997949B2 (en) | 1990-04-17 | 2000-01-11 | アイ・アール・オー エー・ビー | Method and apparatus for spinning system |
US5069222A (en) * | 1990-08-31 | 1991-12-03 | Mcdonald Jr Lewis D | Respiration sensor set |
US5117819A (en) * | 1990-09-10 | 1992-06-02 | Healthdyne, Inc. | Nasal positive pressure device |
US5178138A (en) * | 1990-09-11 | 1993-01-12 | Walstrom Dennis R | Drug delivery device |
US5280784A (en) | 1990-09-19 | 1994-01-25 | Paul Ritzau Pari-Werk Gmbh | Device in particular and inhalating device for treating the lung and the respiratory tracts |
US5099837A (en) | 1990-09-28 | 1992-03-31 | Russel Sr Larry L | Inhalation-based control of medical gas |
SE500447C2 (en) | 1990-10-31 | 1994-06-27 | Siemens Elema Ab | ventilator |
US5063938A (en) | 1990-11-01 | 1991-11-12 | Beck Donald C | Respiration-signalling device |
EP0491969B1 (en) | 1990-12-20 | 1995-08-23 | Siemens-Elema AB | Lung ventilator with a flow rate dependent trigger threshold |
FR2672221B1 (en) | 1991-02-06 | 1993-04-23 | Matisec | DEVICE FOR THE AIR SUPPLY OF NON-AUTONOMOUS BREATHING APPARATUS. |
US5161541A (en) | 1991-03-05 | 1992-11-10 | Edentec | Flow sensor system |
US5450336A (en) | 1991-03-05 | 1995-09-12 | Aradigm Corporation | Method for correcting the drift offset of a transducer |
US5404871A (en) | 1991-03-05 | 1995-04-11 | Aradigm | Delivery of aerosol medications for inspiration |
FR2674133B1 (en) | 1991-03-21 | 1993-06-11 | Taema | RESPIRATORY GAS PRESSURE SUPPLY SYSTEM AND METHOD FOR CONTROLLING SUCH A SYSTEM. |
SE9101097L (en) | 1991-04-12 | 1992-05-18 | Sundstrom Safety Ab | MOVE TO CONTROL AN AIR SUPPLY UNIT RESPIRATORY SYNCHRONIZED FOR A RESPIRATORY PROTECTOR WHICH AATMINSTONE TAKES THE NURSE AND / OR Mouth |
DE4111965C2 (en) | 1991-04-12 | 2000-03-23 | Draegerwerk Ag | Method for calibrating a flow sensor in a breathing system |
US5239994A (en) | 1991-05-10 | 1993-08-31 | Bunnell Incorporated | Jet ventilator system |
IL98228A (en) | 1991-05-23 | 1996-01-31 | Shtalryd Haim | Apnea monitor |
US5174287A (en) * | 1991-05-28 | 1992-12-29 | Medtronic, Inc. | Airway feedback measurement system responsive to detected inspiration and obstructive apnea event |
US5458137A (en) | 1991-06-14 | 1995-10-17 | Respironics, Inc. | Method and apparatus for controlling sleep disorder breathing |
US5203343A (en) | 1991-06-14 | 1993-04-20 | Board Of Regents, The University Of Texas System | Method and apparatus for controlling sleep disorder breathing |
DE4122069A1 (en) | 1991-07-04 | 1993-01-07 | Draegerwerk Ag | METHOD FOR DETECTING A PATIENT'S BREATHING PHASES IN ASSISTANT VENTILATION METHODS |
US5293864A (en) | 1991-08-01 | 1994-03-15 | Geomet Technologies, Inc. | Emergency breathing apparatus |
US5303698A (en) | 1991-08-27 | 1994-04-19 | The Boc Group, Inc. | Medical ventilator |
US5233983A (en) | 1991-09-03 | 1993-08-10 | Medtronic, Inc. | Method and apparatus for apnea patient screening |
US5360946A (en) | 1991-09-17 | 1994-11-01 | International Business Machines Corporation | Flex tape protective coating |
US5190048A (en) * | 1991-09-17 | 1993-03-02 | Healthdyne, Inc. | Thermistor airflow sensor assembly |
US5295491A (en) | 1991-09-26 | 1994-03-22 | Sam Technology, Inc. | Non-invasive human neurocognitive performance capability testing method and system |
GB2261290B (en) | 1991-11-07 | 1995-09-20 | Alan Remy Magill | Health monitoring |
JP3566285B2 (en) | 1991-11-14 | 2004-09-15 | ユニバーシティー テクノロジーズ インターナショナル インコーポレイテッド | Automatic CPAP system |
US5271391A (en) | 1991-12-20 | 1993-12-21 | Linda Graves | Apparatus for delivering a continuous positive airway pressure to an infant |
US5231979A (en) | 1992-02-14 | 1993-08-03 | Puritan-Bennett Corporation | Humidifier for CPAP device |
US5183983A (en) * | 1992-03-20 | 1993-02-02 | Dwyer Instruments, Inc. | Flow switch assembly for fluid flow monitoring |
US5335654A (en) | 1992-05-07 | 1994-08-09 | New York University | Method and apparatus for continuous adjustment of positive airway pressure for treating obstructive sleep apnea |
US5490502A (en) | 1992-05-07 | 1996-02-13 | New York University | Method and apparatus for optimizing the continuous positive airway pressure for treating obstructive sleep apnea |
US5803066A (en) | 1992-05-07 | 1998-09-08 | New York University | Method and apparatus for optimizing the continuous positive airway pressure for treating obstructive sleep apnea |
US5645054A (en) | 1992-06-01 | 1997-07-08 | Sleepnet Corp. | Device and method for the treatment of sleep apnea syndrome |
US5343878A (en) | 1992-06-08 | 1994-09-06 | Respironics Inc. | Pressure application method |
DE69331951T2 (en) | 1992-08-19 | 2003-01-09 | Lawrence A Lynn | DEVICE FOR DISPLAYING APNOE WHILE SLEEPING |
US5353788A (en) | 1992-09-21 | 1994-10-11 | Miles Laughton E | Cardio-respiratory control and monitoring system for determining CPAP pressure for apnea treatment |
GB9222475D0 (en) | 1992-10-24 | 1992-12-09 | Mangar Aids Ltd | Air pump apparatus |
US5311875A (en) | 1992-11-17 | 1994-05-17 | Peter Stasz | Breath sensing apparatus |
US5360008A (en) | 1992-11-18 | 1994-11-01 | Campbell Jr William G | Respiratory and cardiac monitor |
US5590648A (en) | 1992-11-30 | 1997-01-07 | Tremont Medical | Personal health care system |
US5517983A (en) | 1992-12-09 | 1996-05-21 | Puritan Bennett Corporation | Compliance meter for respiratory therapy |
US5438980A (en) | 1993-01-12 | 1995-08-08 | Puritan-Bennett Corporation | Inhalation/exhalation respiratory phase detection circuit |
US5327899A (en) | 1993-01-22 | 1994-07-12 | The Johns Hopkins University | Polygraph automated scoring systems |
US5305787A (en) | 1993-02-03 | 1994-04-26 | C & S Valve Company | Disk valve with improved disk mounting |
US5797852A (en) | 1993-02-04 | 1998-08-25 | Local Silence, Inc. | Sleep apnea screening and/or detecting apparatus and method |
GB9302291D0 (en) | 1993-02-05 | 1993-03-24 | Univ Manitoba | Method for improved control of airway pressure during mechanical ventilation |
US5443075A (en) | 1993-03-01 | 1995-08-22 | Puritan-Bennett Corporation | Flow measuring apparatus |
JP3117834B2 (en) * | 1993-03-02 | 2000-12-18 | 東京瓦斯株式会社 | Gas leak detection method |
JP3117835B2 (en) * | 1993-03-02 | 2000-12-18 | 東京瓦斯株式会社 | Gas leak detection method |
US5633552A (en) | 1993-06-04 | 1997-05-27 | The Regents Of The University Of California | Cantilever pressure transducer |
US5394882A (en) | 1993-07-21 | 1995-03-07 | Respironics, Inc. | Physiological monitoring system |
US5685296A (en) | 1993-07-30 | 1997-11-11 | Respironics Inc. | Flow regulating valve and method |
US5655520A (en) | 1993-08-23 | 1997-08-12 | Howe; Harvey James | Flexible valve for administering constant flow rates of medicine from a nebulizer |
US5413111A (en) | 1993-08-24 | 1995-05-09 | Healthdyne Technologies, Inc. | Bead thermistor airflow sensor assembly |
US5526805A (en) | 1993-11-03 | 1996-06-18 | Dryden Engineering Company, Inc. | In-line silencer for clean room breathing apparatus |
EP1488743A3 (en) * | 1993-11-05 | 2005-01-12 | Resmed Limited | Control of CPAP Treatment |
AUPM279393A0 (en) | 1993-12-03 | 1994-01-06 | Rescare Limited | Estimation of flow and detection of breathing in cpap treatment |
US5398673A (en) | 1993-12-10 | 1995-03-21 | Environmental Support Systems, Inc. | Resuscitator-snorkel for land or water use |
US5570682A (en) | 1993-12-14 | 1996-11-05 | Ethex International, Inc. | Passive inspiratory nebulizer system |
US5479920A (en) | 1994-03-01 | 1996-01-02 | Vortran Medical Technology, Inc. | Breath actuated medicinal aerosol delivery apparatus |
US6105575A (en) * | 1994-06-03 | 2000-08-22 | Respironics, Inc. | Method and apparatus for providing positive airway pressure to a patient |
US5794615A (en) | 1994-06-03 | 1998-08-18 | Respironics, Inc. | Method and apparatus for providing proportional positive airway pressure to treat congestive heart failure |
US5535738A (en) | 1994-06-03 | 1996-07-16 | Respironics, Inc. | Method and apparatus for providing proportional positive airway pressure to treat sleep disordered breathing |
US5642730A (en) | 1994-06-17 | 1997-07-01 | Trudell Medical Limited | Catheter system for delivery of aerosolized medicine for use with pressurized propellant canister |
US5509404A (en) | 1994-07-11 | 1996-04-23 | Aradigm Corporation | Intrapulmonary drug delivery within therapeutically relevant inspiratory flow/volume values |
US5666946A (en) | 1994-07-13 | 1997-09-16 | Respirogenics Corporation | Apparatus for delivering drugs to the lungs |
FI954092A (en) | 1994-09-08 | 1996-03-09 | Weinmann G Geraete Med | Method of controlling a respirator in the treatment of sleep apnea |
DE4432219C1 (en) | 1994-09-10 | 1996-04-11 | Draegerwerk Ag | Automatic breathing system for patients |
US5546952A (en) | 1994-09-21 | 1996-08-20 | Medtronic, Inc. | Method and apparatus for detection of a respiratory waveform |
US5483969A (en) | 1994-09-21 | 1996-01-16 | Medtronic, Inc. | Method and apparatus for providing a respiratory effort waveform for the treatment of obstructive sleep apnea |
US5549655A (en) | 1994-09-21 | 1996-08-27 | Medtronic, Inc. | Method and apparatus for synchronized treatment of obstructive sleep apnea |
US5540733A (en) | 1994-09-21 | 1996-07-30 | Medtronic, Inc. | Method and apparatus for detecting and treating obstructive sleep apnea |
US5509414A (en) | 1994-09-27 | 1996-04-23 | Hok Instrument Ab | Apparatus and method for non-contacting detection of respiration |
US5503146A (en) | 1994-10-26 | 1996-04-02 | Devilbiss Health Care, Inc. | Standby control for CPAP apparatus |
US5567127A (en) | 1994-11-09 | 1996-10-22 | Wentz; Kennith W. | Low noise air blower |
US5540220A (en) | 1994-12-08 | 1996-07-30 | Bear Medical Systems, Inc. | Pressure-limited, time-cycled pulmonary ventilation with volume-cycle override |
US5588439A (en) | 1995-01-10 | 1996-12-31 | Nellcor Incorporated | Acoustic impulse respirometer and method |
SE9500175L (en) | 1995-01-19 | 1996-07-20 | Siemens Elema Ab | Method and apparatus for identifying at least one anesthetic in an anesthetic device |
US5540219A (en) | 1995-01-26 | 1996-07-30 | Respironics, Inc. | Sleep apnea treatment apparatus |
US5537997A (en) | 1995-01-26 | 1996-07-23 | Respironics, Inc. | Sleep apnea treatment apparatus and passive humidifier for use therewith |
SE9500275L (en) | 1995-01-26 | 1996-07-27 | Siemens Elema Ab | Method and apparatus for determining a transfer function for a connection system |
US5598838A (en) | 1995-04-07 | 1997-02-04 | Healthdyne Technologies, Inc. | Pressure support ventilatory assist system |
US5799652A (en) | 1995-05-22 | 1998-09-01 | Hypoxico Inc. | Hypoxic room system and equipment for Hypoxic training and therapy at standard atmospheric pressure |
US5513631A (en) | 1995-07-21 | 1996-05-07 | Infrasonics, Inc. | Triggering of patient ventilator responsive to a precursor signal |
SE9504313L (en) | 1995-12-01 | 1996-12-16 | Siemens Elema Ab | Method for pressure measurement in fan systems by means of two separate gas lines and one fan system |
US5682878A (en) | 1995-12-07 | 1997-11-04 | Respironics, Inc. | Start-up ramp system for CPAP system with multiple ramp shape selection |
US6119686A (en) | 1996-03-29 | 2000-09-19 | Datex-Ohmeda, Inc. | Apnea detection for medical ventilator |
US5730121A (en) | 1996-07-19 | 1998-03-24 | Hawkins, Jr.; Albert D. | Emergency air system |
AUPO163896A0 (en) * | 1996-08-14 | 1996-09-05 | Resmed Limited | Determination of respiratory airflow |
US5701883A (en) | 1996-09-03 | 1997-12-30 | Respironics, Inc. | Oxygen mixing in a blower-based ventilator |
AUPO247496A0 (en) | 1996-09-23 | 1996-10-17 | Resmed Limited | Assisted ventilation to match patient respiratory need |
AUPO301796A0 (en) | 1996-10-16 | 1996-11-07 | Resmed Limited | A vent valve apparatus |
US5865174A (en) | 1996-10-29 | 1999-02-02 | The Scott Fetzer Company | Supplemental oxygen delivery apparatus and method |
AUPO418696A0 (en) | 1996-12-12 | 1997-01-16 | Resmed Limited | A substance delivery apparatus |
US6142150A (en) * | 1998-03-24 | 2000-11-07 | Nellcor Puritan-Bennett | Compliance compensation in volume control ventilator |
AUPP366398A0 (en) * | 1998-05-22 | 1998-06-18 | Resmed Limited | Ventilatory assistance for treatment of cardiac failure and cheyne-stokes breathing |
AUPP370198A0 (en) * | 1998-05-25 | 1998-06-18 | Resmed Limited | Control of the administration of continuous positive airway pressure treatment |
AUPP693398A0 (en) * | 1998-11-05 | 1998-12-03 | Resmed Limited | Fault diagnosis in CPAP and NIPPV devices |
AUPP783198A0 (en) * | 1998-12-21 | 1999-01-21 | Resmed Limited | Determination of mask fitting pressure and correct mask fit |
US6349724B1 (en) * | 2000-07-05 | 2002-02-26 | Compumedics Sleep Pty. Ltd. | Dual-pressure blower for positive air pressure device |
JP4336496B2 (en) | 2000-12-29 | 2009-09-30 | レスメド・リミテッド | Characterizing the mask system |
EP2789359A3 (en) * | 2006-08-30 | 2014-12-24 | ResMed Ltd. | Determination of leak during CPAP treatment |
-
1996
- 1996-08-14 AU AUPO1638A patent/AUPO163896A0/en not_active Abandoned
-
1997
- 1997-08-14 EP EP97934382A patent/EP0929336B1/en not_active Expired - Lifetime
- 1997-08-14 AU AU37625/97A patent/AU731800B2/en not_active Ceased
- 1997-08-14 CA CA002263126A patent/CA2263126C/en not_active Expired - Fee Related
- 1997-08-14 US US08/911,513 patent/US6152129A/en not_active Expired - Lifetime
- 1997-08-14 DE DE69736808T patent/DE69736808T2/en not_active Expired - Lifetime
- 1997-08-14 AT AT97934382T patent/ATE342083T1/en not_active IP Right Cessation
- 1997-08-14 JP JP50923998A patent/JP3635097B2/en not_active Expired - Fee Related
- 1997-08-14 WO PCT/AU1997/000517 patent/WO1998006449A1/en active IP Right Grant
-
2000
- 2000-03-14 US US09/525,042 patent/US6279569B1/en not_active Expired - Lifetime
-
2001
- 2001-07-10 US US09/902,011 patent/US6659101B2/en not_active Expired - Lifetime
-
2003
- 2003-12-01 US US10/726,114 patent/US6945248B2/en not_active Expired - Lifetime
-
2005
- 2005-09-08 US US11/223,237 patent/US7661428B2/en not_active Expired - Fee Related
-
2009
- 2009-12-30 US US12/649,877 patent/US8763609B2/en not_active Expired - Fee Related
-
2014
- 2014-05-15 US US14/278,642 patent/US20140331998A1/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3961627A (en) * | 1973-09-07 | 1976-06-08 | Hoffmann-La Roche Inc. | Automatic regulation of respirators |
US4671297A (en) * | 1985-10-25 | 1987-06-09 | Schulze Jr Karl F | Method and apparatus for monitoring infants on assisted ventilation |
US5129390A (en) * | 1987-12-18 | 1992-07-14 | Institut Nationale De La Sante Et De La Recherche Medicale | Process for regulating an artificial ventilation device and such device |
US5619986A (en) * | 1991-01-03 | 1997-04-15 | Olof Werner | Method and apparatus for controlling the concentration of at least one component in a gas mixture in an anaesthetic system |
US5347843A (en) * | 1992-09-23 | 1994-09-20 | Korr Medical Technologies Inc. | Differential pressure flowmeter with enhanced signal processing for respiratory flow measurement |
US5551419A (en) * | 1994-12-15 | 1996-09-03 | Devilbiss Health Care, Inc. | Control for CPAP apparatus |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130255682A1 (en) * | 2012-03-30 | 2013-10-03 | Nellcor Puritan Bennett Llc | Methods and systems for compensation of tubing related loss effects |
US9327089B2 (en) * | 2012-03-30 | 2016-05-03 | Covidien Lp | Methods and systems for compensation of tubing related loss effects |
Also Published As
Publication number | Publication date |
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JP3635097B2 (en) | 2005-03-30 |
US6279569B1 (en) | 2001-08-28 |
DE69736808T2 (en) | 2007-08-16 |
US20040074492A1 (en) | 2004-04-22 |
DE69736808D1 (en) | 2006-11-23 |
US7661428B2 (en) | 2010-02-16 |
US6659101B2 (en) | 2003-12-09 |
AU731800B2 (en) | 2001-04-05 |
EP0929336B1 (en) | 2006-10-11 |
AU3762597A (en) | 1998-03-06 |
US8763609B2 (en) | 2014-07-01 |
US20060005835A1 (en) | 2006-01-12 |
US6152129A (en) | 2000-11-28 |
US20100101576A1 (en) | 2010-04-29 |
WO1998006449A1 (en) | 1998-02-19 |
ATE342083T1 (en) | 2006-11-15 |
CA2263126A1 (en) | 1998-02-19 |
EP0929336A1 (en) | 1999-07-21 |
CA2263126C (en) | 2005-11-29 |
EP0929336A4 (en) | 2003-04-02 |
US20020069874A1 (en) | 2002-06-13 |
US6945248B2 (en) | 2005-09-20 |
JP2000516491A (en) | 2000-12-12 |
AUPO163896A0 (en) | 1996-09-05 |
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