WO2013043504A1

WO2013043504A1 - Pulsated oxygen delivery for medical applications

Info

Publication number: WO2013043504A1
Application number: PCT/US2012/055514
Authority: WO
Inventors: Joel B. METELITS
Original assignee: Metelits Joel B
Priority date: 2011-09-20
Filing date: 2012-09-14
Publication date: 2013-03-28

Abstract

A fluid delivery system provides fluid, such as supplementary oxygen, to a patient in periodic time intervals. The fluid delivery system includes a pressure valve assembly that is opened as a result of change in flow caused by a patient's inhalation and closed after inhalation.

Description

Pulsated Oxygen Delivery for Medical Applications

The invention relates to devices and methods for effectively and efficiently delivering oxygen to hypoxic patients. In the US today, approximately 1 million Medicare patients are being treated on long term oxygen therapy— a number which is only a small fraction of patients who use or need oxygen The detrimental impact of chronic hypoxemia may be mitigated by the administration of long term oxygen therapy (LTOT). The continuous inhalation of oxygen, typically 2-3 liters per minute (1pm), from a nasal cannula increases the concentration of oxygen that the patient is breathing. It is estimated that for each 1 1pm (liter per minute) of supplemental nasal oxygen flow, the patient can increase their blood oxygen concentration rises by 3-4%. The increase in blood oxygen concentration compensates for the poor function of the patient's lungs in absorbing oxygen.

Generally, when a patient is diagnosed with chronic hypoxemia, oxygen is prescribed at a fixed flow rate which is based on a 20 minute titration test in the doctor's office, or on an overnight oximetry measurement which indicates more than 5 minutes of less than or equal to 88% saturation or 5 minutes or more or less than 5 min of oxygen saturation less than 90% in certain clinical conditions.

During the test, the patient's blood oxygen saturation is measured by either using an invasive blood gas analyzer or a non-invasive device such as a pulse oximeter. While measuring the blood saturation (Sp0₂), patients may be sitting or laying down at rest, or be asked to walk about the physician's office, walk on a treadmill, or perform some other strenuous task. They may also be asked to have their blood oxygen content measured during the night while they sleep in their own home (nocturnal oximetry). Based on their testing modalities, if the above stated criteria are met, a fixed flow of oxygen is prescribed. The patient may be advised to increase the flow rate of oxygen during exertion, for example, while climbing stairs, while sleeping or if they feel short of breath. The test which qualified them for oxygen therapy is then repeated while on oxygen therapy to confirm that the problem has been corrected.

Patients may be prescribed supplemental oxygen 24 hours per day, during exertion, or just during sleep— depending on their needs. If a patient needs to breathe oxygen even while resting, they often will need a stationary oxygen- generating unit, known as a concentrating unit, which can be set up to produce up to 10 1pm depending on patients' needs. If patients require oxygen while ambulating, they typically will carry small high-pressure oxygen cylinders or small refillable liquid oxygen dewars. Small portable oxygen generators also have been introduced into the market, but they are often unable to deliver more than 3-4 1pm. They must have a power supply (battery or plug in to AC current) and carry the drawbacks of more weight than portable cylinders, and shorter battery life. Due to the expense of providing oxygen in small cylinders and dewars for ambulation, the need to conserve oxygen flow was addressed by the development of oxygen conserving devices. These devices only deliver short pulses of oxygen at the beginning of a patient's inhalation. By not delivering oxygen during exhalation or the later period of inhalation, the oxygen, which would have had no impact on increasing the patient's oxygen saturation is conserved. Various methods exist to accomplish this efficiency in oxygen treatment management, and are expressed in ratios of oxygen flow required by the conserving device compared to the gold standard of continuous flow to achieve the same therapeutic oxygen saturation. Currently available devices can achieve conserving ratios from 2: 1 to 6: 1. As a result, a small cylinder can provide useful quantities of oxygen up to six times longer than those with continuous flow. The higher conservation ratios are achieved by various methods which deliver the supplemental oxygen in the most optimal phase of inspiration (before the end of the first half second of inspiration) so that the oxygen will be available for oxygen exchange in the only part of the lung designed for the oxygen absorption— the alveoli.

Unfortunately pitfalls are present in all of the delivery systems. Situations which are most challenging for oxygen delivery systems include times when a patient's inspiratory efforts are directed through their mouth as opposed to their nasal passages.

Clearly exercise can demand mouth breathing and sleep can involve unconscious mouth breathing. When a patient breaths through their mouth, even the gold standard continuous flow oxygen looses efficiency as the 100% oxygen is diluted with increasing amounts of ambient air. The pulse oxygen delivery system gets lost during mouth breathing— which can only be accommodated by pulse timing algorithms or reservoir systems which fall short of the gold standard continuous flow efficiency and thus fall short of the advertised efficiency ratios.

Many schemas exist to sense breathing and trigger timed oxygen release— using electronic and or pneumatic sensors. One design currently patented and marketed spits the nasal cannula in half - one half of each nasal prong is a separate pathway. The first half of the split lumen pneumatically senses inspiration, second half of the lumen is to deliver the oxygen. None of the currently available oxygen delivery systems effectively overcome the limitations of mouth breathing.

Current gold standard continuous oxygen delivery by nasal cannula is beset with other problems besides inefficiency. Humidification of the oxygen is attempted, but excess humidification can deliver water to the patient's nostrils and maximum effective humidification often results in excessive drying of the nasal passages and mouth. Various topical treatments are available for the reachable mucosa of the nostrils, but symptomatic nasal irritation is almost inevitable.

When oximetry is performed on patients treated with long term oxygen and the levels are below 90% saturated, the patient's oxygen flow rates are increased to correct the oxygen deficiency. Oxygen flow rates are often higher while sleeping than during awake states. This is why some patient's only need supplemental oxygen when sleeping but are perfectly fine when awake. The amount of oxygen a patient needs while sleeping can often be reduced if a patient can keep their mouth closed— thereby stopping mouth breathing. Higher and higher nasal oxygen flow rates are the reflex answer to low oxygen levels since patient's compliance with face mask oxygen is very low.

Adequate long term oxygen therapy (LTOT) is problematic since current methods of treatment have room for improvement. In an article by Fussell et al. (Respiratory Care-February 2003, Vol. 48 No. 2). The authors stated: "Resting oxygen saturation (measured via pulse oximetry [Sp02]) and lowest exercise Sp02 (during a 6-min walk test) is the standard method of determining LTOT

requirements, but that method does not measure the patient's oxygenation during sleep or activities of daily living." In this study, 20 patient's blood saturation levels were monitored continuously using pulse oximeters to confirm if their oxygen prescription adequately maintained their saturation. The conclusion of the study was that there was a poor relationship between conventional oxygenation assessment methods and continuous ambulatory oximetry during LTOT screening with COPD patients.

In a more recent article by Palwai et al Am J Respir Crit Care Med. 2010 May 15;181(10): 1061-71. Epub 2010 Feb 4. Entitled "Critical comparisons of the clinical performance of oxygen-conserving devices". Thirteen patients with COPD (chronic obstructive lung disease) performed "progressive treadmill exercise while inhaling either room air, 2 L 0(2)/min, or bolus oxygen from four commercially available conserving devices at regulator settings of 2, 5, and continuous. The devices were studied blindly in random order after first being tested to determine performance characteristics. Pulse oximetry, oxygen delivery, and nasal and oral ventilations were monitored at rest and with exertion." The authors concluded: "The mechanical and clinical performances of current oxygen conservers are highly variable and in some instances actually contribute to limitations in exercise ability. Seemingly equivalent technical features do not guarantee equivalent therapeutic functionality."

In addition to frequently failing at their mission, conserving oxygen devices often give the patient and medical providers a false sense of security. Patients who travel with oxygen conservation devices are particularly vulnerable to issues of increased costs, battery capacity, and at times reliance on less than ideal pulse triggering technology. A large nostriled individual will not trigger a standard conserving regulator without some training— which eliminates functional use during sleep when training has no impact. A person walking across a parking lot may need to stop walking and focus on nasal breathing to trigger most currently available devises.

Moreover, some COPD patients who use stationary oxygen concentrators in their homes are often impacted by the size of the units, the noise of the units, and the hidden electricity costs which can easily add up to 30-60 dollars of electricity costs per month. In many cases this has led to a compliance issue where the patient may elect to not switch on the concentrator and follow the therapy as prescribed by the doctor in order to allow a spouse to sleep in the room with them, or to avoid heating their bedroom, and in some cases to save on their electricity costs. CuiTently available oxygen concentrators throw a fair amount of heat into the room, which may further add to energy costs, i.e. for cooling the room. Current oxygen concentrator designs will typically produce a maximum flowrate, of 4 1pm, 5 1pm or 10 1pm. Many oxygen therapy patients can spend a significant amount of their time while resting with blood saturation levels which are either too high or too low. The foregoing discussion of the prior art derives in part from U.S. Patent 7,222,624 in which there is described methods and apparatus for supplying respiratory oxygen to a patient in which oxygen flow is monitored in response to the patient's pulse rate and blood hemoglobin saturation. However, such system requires the patient to wear a pulse oximeter, which while fine for a bedridden patient, is not acceptable to an ambulatory patient.

Furthermore, there are other problems with current oxygen generating systems which rely on cannula for delivering oxygen to the nasal passages of a patient. Some patients are mouth breathers particularly when they get out of breath. Also, many patients, when they sleep, tend to breath more through their mouth. As a result, proper oxygen blood levels may not be maintained.

It is therefore an object of the present invention to provide an oxygen delivery system that overcomes the aforesaid and other disadvantages of the prior art.

The present invention provides an oxygen delivery system comprising a dual sensing device separately triggered through the mouth and through the nose of a patient, to whichever orifice is "requesting" the oxygen thereby efficiently delivering the oxygen where the inflow of air can most effectively get to the lung alveoli and efficiently supplement the patent's needed oxygenation. Clearly an oxygen mask with continuous flow could do the same thing, but with much more "discomfort" and with a lot of wasted supplemental oxygen as there are no available conserving mask triggered oxygenators. More particularly, in accordance with the present invention, there is provided an apparatus separately sensing nasal air flow and oral air flow-each sensor connected to a conservation oxygen regulator regular which will efficiently deliver a supplemental pulse of oxygen through the pathway that initiated the air flow and hence triggered the sensor.

In one embodiment the oral and nasal pathways use separated solenoid oxygen conserving regulators and in another embodiment the oral and nasal pathways share one oxygen conserving regulator.

In one embodiment of the invention, the oxygen conserver controller includes a pressure valve assembly adapted to open upon detection of pressure reduction on patient inhalation, and close until the patient takes another breath. In another embodiment of the invention, the system includes an electronic remote sensor and trigger mechanism for controlling the oxygen conserver controller.

The invention will be better understood from a reading of the following detailed description taken in conjunction with the drawings in which like reference designators are used to designate like elements, and in which:

FIG. 1 is a block diagram of a system for fluid delivery in accordance with a first embodiment of the present invention;

FIGs. 2 A and 2B are schematics each illustrating actuation of a pressure valve assembly in accordance with the first embodiment of the present invention;

FIG. 3 A - 3C are schematics illustrating a Diaphragm Effect in accordance with the first embodiment of the present invention;

FIGs. 4 - 6 are schematics of various embodiments of oronasal cannulae in accordance with the first embodiment of the present invention;

FIGs. 7A - 7C are a series of graphs illustrating airflow in a patient in accordance with the present invention;

FIG. 7D is a graph illustrating oxygen flow from a fluid delivery system in accordance with the present invention;

FIG. 8 A is a graph illustrating a tidal volume of a patient with COPD;

FIG. 8B is a graph illustrating time/volume oxygen delivery to a patient in accordance with the present invention; and

FIG. 9A is a schematic of the second embodiment of the present invention; FIG. 9B is an enlarged perspective view of a nasal flow sensor element of the Fig. 9 embodiment;

FIG. 9C is an enlarged perspective view of an oral flow sensor element of the Fig. 9 embodiment;

FIG. 9D is an exploded view of a valve assembly in accordance with a second embodiment of the present invention;

FIG. 10 is a block diagram of a trigger mechanism in accordance with the second embodiment of the present invention;

FIG. 11 is a block diagram of a remote sensor in accordance with the second embodiment of the present invention;

FIG. 12 is a graph illustrating oxygen flow from a fluid delivery system in accordance with a second embodiment of the present invention.

Embodiments are described in the following description with reference to the drawing figures in which like numbers represent the same or similar elements. Reference throughout this specification to "one embodiment," "an embodiment," "certain embodiments," or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment", "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The described features, structures, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are recited to provide a thorough

understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

The fluid delivery system of the present invention provides oxygen, to a patient in intermittent, periodic, or pulsated time intervals. The fluid delivery system includes a pressure valve assembly that opens as a result of change in pressure caused by a patient's inhalation, and closes after inhalation. Consequently, the flow of supplementary oxygen is turned on and off in response to the patient's respiratory cycle. As a result, supplementary oxygen is conserved because the supplementary oxygen is not provided when the patient is not breathing in.

Inhalation is the movement of air from the external environment, through the airways, and into the lungs. During inhalation, the chest expands and the diaphragm contracts downwardly or caudally, resulting in expansion of the intrapleural space and a negative pressure within the chest cavity. This negative pressure results in airflow from either the nose or the mouth into the pharynx (throat) and trachea, eventually entering the lungs.

Referring to FIG. I, the fluid delivery system 100 of the present invention comprises a fluid source 102 and a fluid regulator 104 coupled to the fluid source 102. Examples of fluid sources 102 include: an oxygen generation apparatus, a stationary oxygen reservoir within a hospital setting, or a portable canister of pressurized oxygen, a liquid oxygen dewar, or a pressurized oxygen reservoir. In certain embodiments the fluid delivery system 100 further includes a power source 1 12, such as a battery or utility power.

The fluid regulator 104 discontinues oxygen flow at a predetermined pressure at the outlet end 108. Preferably, the fluid regulator 104 includes a dual pressure gauge that measures inlet pressure at the source 102 (e.g., oxygen left in the fluid source 102), and outlet pressure at the outlet end 108.

As will be described below in greater detail, the fluid regulator 104 triggers a pressure valve assembly open at patient inhalation and/or triggers the pressure valve assembly closed at patient exhalation. As used herein, inhalation is used

synonymously with inspiration, and exhalation is used synonymously with expiration.

FIG. 2 A illustrates a pressure valve assembly 120 in an open configuration wherein oxygen from source 102 is provided to patient 106 via an oronasal cannula shown generally at 130, and FIG. 2B illustrates a pressure valve assembly 120 in a closed configuration wherein oxygen from source 102 is not provided to patient 106.

When patient 106 inhales, the negative pressure in the patient's nose and mouth induces a pressure drop in cannula 130. Fluid regulator 104 detects this pressure reduction at outlet end 108 and triggers pressure valve assembly 120 to the open configuration of FIG. 2 A. When patient 106 exhales, the pressure in the cannula increases. Fluid regulator 104 detects this pressure increase at outlet end 108 and triggers pressure valve assembly 120 to the closed configuration of FIG. 2B.

In certain embodiments, the negative pressure upon inhalation may be caused, in part, by the Bernouli Effect. Here, the streamline of air (e.g., from either the nose or the mouth) causes a pressure lift at the opening of the proximal end of the cannula near the nose or mouth. For example, when the opening of the proximal end is configured at an angle to the streamline of air during respiration, a drop in pressure occurs due to the increased velocity of the passage of air across the rim of the proximal end of the cannula. This drop in pressure triggers the pressure valve assembly 120 to open. Preferably but not necessarily, the opening of the proximal end is configured to be substantially orthogonal to the streamline of air during respiration.

In certain embodiments, the negative pressure upon inhalation may be caused, in part, by the Diaphragm Effect. The active process of breathing requires the contraction of skeletal muscles within the chest cavity, including the external intercoastal muscles (located between the ribs) and the diaphragm (a flat muscle located between the thoracic & abdominal cavities).

Exhalation is the movement of air from the lungs to the external

environment as the intercoastal muscles relax and the diaphragm moves upwardly in the coronal direction inducing a positive pressure throughout the patient's respiratory system. This positive pressure in the patient's mouth and nose induces a pressure increase in cannula 130. Fluid regulator 104 detects this pressure increase at outlet end 108 and triggers pressure valve assembly 120 to the closed

configuration of FIG. 2B.

Referring to FIG. 3A-C, the Diaphragm Effect is further explained. FIG. 3 A represents the diaphragm at rest during the end of passive exhalation. The intrapleural pressure is illustrated to be about -5mm Hg. Because the alveolar pressure is zero and the atmospheric pressure is zero, there is no gradient between the nasopharynx and the lungs. Therefore, there is no net movement of air. FIG. 3B represents diaphragmatic contraction during inspiration. The intrapleural pressure is more negative (e.g., -7 mm Hg verus -5mm llg) and the alveolar pressure is about - 5 mm llg, for example. Because the atmospheric pressure is zero, a pressure gradient exists such that there is a net movement of air into the lungs. FIG. 3C represents diaphragmatic relaxation during exhalation. Both the intrapleural pressure and the alveolar pressure are positive. Because the atmospheric pressure is zero, a pressure gradient exists such that there is a net movement of air out of the lungs.

FIGs. 4 - 6 illustrate a plurality of embodiments of oronasal cannula 130. FIG. 4A shows a front elevation view of nose 222 and mouth 518 of patient 106 in the XY plane of a Cartesian coordinate system 526. FIG. 4B is a right side elevation view of same. An oronasal cannula 500 has three sections: a nasal section 502; a tubing section 504; and an oral section 506. The nasal section 502 includes at least one nasal cannula, here depicted as nasal cannulae 512 and 514. The tubing section 504 includes tubing of the cannula supplies oxygen from source 102 via the fluid regulator 104. The mouth section 506 includes at least one oral cannula 508 that extends proximal to the mouth 51 8 of the patient.

In certain embodiments, the length of each of the nasal cannula 502 and the oral cannula section 506 is adjustable so that it can accommodate the anatomy of the patient. For example, the oral cannula 508 has detachable components that fit together via a connection section 510. Connection section 510 preferably comprises an adjustable length sleeve. Alternatively, the oronasal cannula of the present invention can comprise a connection section of 510 of fixed length, in which case a plurality of oronasal cannulae of different lengths may be supplied. Other forms of extendable or detachable tubing for the oral and/or nasal cannulae are also contemplated.

The proximal ends of the nasal cannulae 512 and 514 are formed to include openings 513 and 515, respectively. Those skilled in the art will appreciate, that air moves into, and out of, nose 222 along the Z axis.

In certain embodiments, openings 513 and 515 are disposed within the X/Y plane. In such case, in certain embodiments, air moving into, and out of nose 222 passes across openings 513 and 51 5. In these embodiments, the rim of opening 513 and the rim of opening 515 are each substantially orthogonal to the flow of air during nasal respiration. In certain embodiments, proximal ends of the nasal cannulae 512 and 514 extend into the patient's nostrils. In these embodiments, proximal ends of the nasal cannulae 512 and 514 are coaxial with the flow of air during nasal respiration.

In yet other embodiments, the plane of the rim of the openings 513 and 515 are rotated at an angle in the -Z direction within the coordinate system 526. In these embodiments, movement of air into the nose during inspiration will cause induce a negative pressure in cannula 130. However, movement of air outwardly from the nose during exhalation will primarily push against the back of the nasal cannula 512 and 514, and will not induce a negative pressure in cannula 130. Consequently, the orientation of nasal cannula 514 promotes triggering of the pressure valve assembly to open during inhalation while not triggering the pressure valve assembly to open during exhalation.

Similarly, in certain embodiments, the proximal end of the oral cannula 508 has an opening 516 formed therein. Here, the plane of the opening at the proximal end of the oral cannula 508 is non-parallel to the movement of air 514 of air during oral respiration.

Other orientations of the opening of the proximal end of the nasal and/or oral cannulae relative to the streamlines 228 and 524, respectively, are also contemplated. For example, in certain embodiments, the orientation of the opening of the proximal end of the nasal and/or oral cannula relative to the respective streamline is selected from the group consisting of: rotating the plane of the rim between 0-90 degrees about one or more of the X-axis, Y-axis, and Z-axis of the coordinate system 526.

FIGs. 5 and 6 each depict other embodiments of oronasal cannulae in accordance with the present invention. The oronasal cannula includes two nasal cannulae 602 and 604 that each are oriented toward the center of the nose and two oral cannulae 606 and 608 that are each oriented toward the center of the mouth. FIG. 5 also depicts a mouth guard 610 that caps the mouth to reduces release of supplementary oxygen into the ambient environment. FIG. 6 depicts an oronasal cannula with two nasal cannulae each with openings that face directly into the patient's streamline of air and two oral cannulae 704 and 706 that each have a bent orientation.

In certain embodiments, supplementary oxygen is delivered during predetermined phases within the respiratory cycle. Referring to FIGs. 7A-7D, graphs depict the inspiration phase 802 and the expiration phase 804 of the respiratory cycle. FIG. 7A illustrates intra-alveolar pressure, FIG. 7B illustrates intrapleural pressure, and FIG. 7C illustrates the volume of air movement during the respiratory cycle. FIG. 7D illustrates the amount of supplementary oxygen delivered 806 by conventional means. As illustrated conventional means 806 delivers supplementary oxygen in a continuous fashion, independent of the phases of the respiratory cycle. In contrast, supplementary oxygen is delivered in an intermittent or pulsated fashion when using the fluid delivery system 100 of FIG. 1. Here, supplementary oxygen is delivered during the inspiration phase 802 of the respiratory cycle but not delivered during the expiration phase 804 of the respiratory cycle.

In certain embodiments, the supplementary oxygen is delivered during predetermined sub-phases within the respiratory cycle that will provide the most amount of gas exchange. Tidal volume is the volume of air displaced during respiration, which is about 500 ml or 7 ml/kg bodyweight. Only a portion, however, of the tidal volume is involved in gas exchange in the lungs. Dead space is air that is inhaled but not involved in alveoli gas exchange. Anatomical dead space is the gas that is inhaled that does not come into contact with the alveloli, such as the air that remains in the trachea. Alveolar dead space is gas that is in the alveoli that does not interact with blood flow in adjacent pulmonary capillaries.

For a tidal volume of 450 mL, for example, the first gas to arrive at the alveoli is the 1 0 mL of oxygen poor gas already occupying the dead space in the airways. This is followed by the first 300 mL of inspired gas. The final 150 mL of inspired gas will fill the dead space at the end of inspiration but not reach the alveoli. Ideally, oxygen is delivered prior to this last 150 mL of inspiration.

Referring to FIG. 8 A, a graph 900 depicts tidal volume of a patient with COPD. Here, it is estimated that COPD patient breathing a 3 second breath cycle benefits most during the first 0.5 seconds of inspiration because the tail end of inhalation includes dead space. Using the fluid delivery system 100 of FIG. 1 , the fluid regulator 104 can be constructed to trigger open the pressure valve assembly at time 0 seconds, element 906 of FIG. 8 A, and to trigger shut the pressure valve assembly at time 0.5 seconds, element 908, for example. In this manner, a volume of supplementary oxygen is delivered (area under curve 910-FIG. 8b) to the patient during the initial sub-phase of inspiration. Other pulsed oxygen delivery during sub- phases within the respiratory cycle are also contemplated.

Another and preferred embodiment of the invention is illustrated in FIGs. 9- 12. According to this latter embodiment, the oxygen conserver controller 1000 is triggered on and off by a remote sensor 1002 and trigger mechanism 1004. As will be described below, remote sensor 1002 which may be formed integrally with the oronasal cannula, or located upstream thereof, senses the onset of patient inhalation, and transmits the information to a remote trigger mechanism which in turn turns the conserving regulator 1000 on and off. Any sensor or combination of sensors that can be used to measure or identify the difference in properties between and inhalation and exhalation maneuver that can be used to synchronize and turn the conserving regulator on and off. Examples of sensors that may be used to detect patient inhalation/exhalation include air flow sensors, air pressure sensors, temperature sensors that measure a temperature difference between the inhaled and exhaled breath, carbon dioxide gas sensors that measure the gas component level between the inhaled and exhaled breath, and also physical measurement systems such as strain gauge chest straps to measure the expansion and contraction of a patient's chest cavity. Other sensors such as acoustic sensors that detect the sound of inhalation and exhalation flow such as described in U.S. Published Application No. 2005/0183725 or in U.S. Patent No. 6,152,130 advantageously may be employed. Yet another possible sensor comprises an electro -mechanical sensor having a moveable vane capable of being displaced when air flow is generated by patient inhalation, for example, following the teachings of U.S. Patent 5,655,523.

The remote sensor and trigger mechanism may be hard wired, e.g. by incorporating wires into the tubing, connecting the sensor and trigger mechanism and the oxygen supply, but preferably is designed to communicate wirelessly, for example, using Bluetooth short-wave length radio transmission technology.

Referring in particular to Fig. 9A-9D, the oronasal canula is a modification of Fig. 5 where the size is modified to be less obtrusive but still demonstrates the essential feature of separate channels for access, trigger, and delivery to the nasal passages and or the oral passage way. The separate nasal 1002 and oral 1004 passages in Fig. 9 A have separate nasal and oral flow measurement sensor 1006, 1008, respectively which communicate with trigger amplification mechanism 1010 which will "amplify" the weakest impulse of breath either through the nose or mouth, and retrofit the currently available conserving regulators or ultimately be included in future conserving regulators. A main criteria for the sensor is to sense even the weakest of respiratory efforts and rapidly ~ well within the current standard of 0.5 second of inspiration trigger the release of pulsed oxygen. Since the currently available sensors for conserving units can, in ideal circumstances provide a six to one efficiency ratio, the improved ability to sense oral inspiration can make this dual sensing mechanism available to mouth breathers when sleeping and mouth breathing when walking and unable to oxygenate adequately with the current conserving units. This dual passage effectiveness of oxygen treatment may improve enough to allow hypoxic patients currently limited by 3 liters per min when sleeping to avoid hypoxia with currently available ambulatory oxygen treatment and currently available nocturnal oxygenators small enough for travel.

Referring to Fig. 10; a further enhancement of the Figure 9 and 9A embodiment is illustrated. Reference numbers 1006 and 1008 represent sensors designed to measure infinitesimal flow in the nose 1006 (one path) and the mouth 1008 (a second path) and through microprocessors (1012), both battery powered (1016), which will communicate with the trigger mechanism (1004)

Various possible communications between the trigger amplifier and the conserving regulator (1000), for example, a Bluetooth communicator which would turn on an LED when the battery weakens enough to risk failure to sense efforts of breathing or delivery of oxygen.

Referring also to Figs. 10 and 1 1 , the remote sensor system includes sensors 1006 and 1008 as described above communicating with a microprocessor 1012. An LED 1014 preferably is included to signal that the sensor is on and that the battery 1016 has sufficient charge. The microprocessor 1012 receives signals from sensor 1010, and transmits the signals via a Bluetooth transmitter 1018 to trigger mechanism 1020. The trigger mechanism 1020 includes a Bluetooth receiver 1022 which communicates with microprocessor 1024 for sending signals to a solenoid valve mechanism 1026. Trigger mechanism 1020 includes a battery 1028 and an LED 1030 for signaling when the trigger mechanism is activated and that the battery has sufficient charge.

Although the present invention has been described in detail with reference to certain embodiments, one skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the scope of the appended claims should not be limited to the description of the embodiments contained herein.

Claims

I claim:

1. A fluid delivery system comprising:

a source of oxygen; a pressure valve assembly coupled to said source, wherein the pressure valve assembly is configured to allow flow of oxygen from the source during patient inspiration and disallow the flow of oxygen from the source during patient expiration; and

a nasal cannula and an oral cannula coupled to one another having an inlet end coupled to the pressure valve assembly.

2. The fluid delivery system of claim 1, wherein a rim of a proximal end of at least one of the nasal cannula and the oral cannula is configured to be at an angle to a streamline of the patient inspiration.

3. The fluid delivery system of claim 1 or claim 2, further comprising a power source configured to operate the pressure valve assembly.

4. The fluid delivery system of any of claims 1-3, wherein the nasal cannula and the oral cannula are coupled to one another by an adjustable length sleeve.

5. The fluid delivery system of any of claims 1 -3, wherein the nasal cannula and the oral cannula are coupled to one another by detachable tubing.

6. The fluid delivery system of claim 3, wherein the power source comprises an electrical power source.

7. A physiological sensor for sensing an inhalation of a subject, the sensor comprising:

a pressure value;

tubing including a distal end and a proximal end, where:

the distal end is coupled to the pressure valve; and

a rim of an opening at the proximal end is configured to be in a plane that is at an angle to a streamline of an inhalation of a patient.

8. The sensor of claim 7, further comprising a trigger mechanism for triggering release of oxygen through the valve.

9. The sensor of claim 8, wherein the trigger mechanism is electrically driven.

10. An intermittent fluid delivery apparatus, the apparatus comprising:

a pressure valve configured to be coupled to a fluid source;

a tubing including a distal end and a proximal end, where:

the distal end is coupled to the pressure valve; and

11. The fluid delivery apparatus of claim 10, further comprising a trigger mechanism for triggering release of fluid through said pressure valve.

12. The fluid delivery apparatus of claim 11 , wherein the trigger mechanism is electrically driven.

13. An apparatus for conserving oxygen being delivered from an oxygen supply to a patient, comprising:

an oxygen conserver controller connected between the oxygen supply and an oronasal cannula including separate oral and nasal cannulae;

a valve for selectively delivering oxygen to the oral and or nasal cannulae; a sensor for sensing patient inhalation; and

a trigger mechanism, communicating with said sensor for actuating the conserving regulator.

14. The system of claim 13, wherein said sensor and said trigger mechanism are remote from one another.

15. The system of claim 13 or claim 14, wherein said sensor and said trigger mechanism are electrically driven.

16. The system of claim 15, wherein said sensor is selected from the group consisting of an acoustic sensor, a flow sensor, a pressure sensor, a temperature sensor, a carbon dioxide sensor, a strain guage, and an electro-mechanical sensor.

17. A system of claim 15, wherein said sensor and said trigger mechanism communicate wirelessly.