WO2008077003A1

WO2008077003A1 - Single blower positive airway pressure device and related method

Info

Publication number: WO2008077003A1
Application number: PCT/US2007/087845
Authority: WO
Inventors: Alonzo C. Aylsworth; Lawrence C. Spector; Charles R. Aylsworth
Original assignee: Acoba, L.L.C.
Priority date: 2006-12-19
Filing date: 2007-12-18
Publication date: 2008-06-26

Abstract

Single blower positive airway pressure device and related method. At least some of the illustrative embodiments are systems comprising a first outlet port configured to couple to a first breathing orifice of a patient, a second outlet port configured to couple to a second breathing orifice of a patient, a single blower fluidly coupled to the first outlet port and the second outlet port (the single blower provides substantially all the therapeutic gas inspired through the first and second breathing orifices, and a first valve fluidly coupled between the single blower and the first outlet port). The system is configured to control pressure of therapeutic gas applied to the first outlet port to be different than pressure of therapeutic gas applied to the second outlet port.

Description

SINGLE BLOWER POSITIVE AIRWAY PRESSURE DEVICE AND RELATED METHOD

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of United States Provisional Patent Application No.

60/870,648, filed December 19, 2006, titled "Single blower positive airway pressure device with individual pressure and flow control," and which application is incorporated by reference herein as if reproduced in full below.

BACKGROUND United States Patent No. 7,114,497 (the '497 patent), sharing two inventors with this specification, describes applying positive airway pressure to a patient for the treatment of sleep- disordered breathing, such as sleep apnea. In particular, in the '497 patent pressure and flow provided to each naris are individually controlled by a dedicated blower and motor for each naris. Each breathing orifice having a dedicated blower may make the cost of the positive airway pressure device too expensive for some consumers, and thus alternative methods and devices are needed that provide the benefit of individual control of applied pressure and flow.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of illustrative embodiments, reference will now be made to the accompanying drawings in which: Figure 1 illustrates a system in accordance with at least some embodiments;

Figure 2A illustrates a valve in accordance with some embodiments; Figure 2B illustrates a valve in accordance with some embodiments; Figure 3 illustrates the system of Figure 1 in a shorthand notation; Figure 4 illustrates other embodiments in the shorthand notation; Figure 5 illustrates yet still other embodiments in the shorthand notation;

Figure 6 illustrates other embodiments in the shorthand notation; Figure 7 illustrates yet still other embodiments in the shorthand notation; Figure 8 A illustrates other embodiments in the shorthand notation; Figure 8B illustrates yet still other embodiments in the shorthand notation; Figure 9 illustrates an overhead view of a control valve in accordance with at least some embodiments;

Figure 1OA illustrates an overhead view of the control valve with a portion of the outer housing removed and with the moveable valve member in a first orientation, in accordance with at least some embodiments; Figure 1OB illustrates an overhead view of the control valve with a portion of the outer housing removed and with the moveable valve member in a second orientation, in accordance with at least some embodiments;

Figure 11 illustrates a side elevation view of the control valve and related stepper motor in accordance with at least some embodiments;

Figure 12 illustrates a disk having apertures therein to determine orientation in accordance with at least some embodiments;

Figure 13 illustrates a method in accordance with at least some embodiments; and Figure 14 illustrates yet still other embodiments in the shorthand notation. NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, medical device companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to... ."

Also, the term "couple" or "couples" is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. The term "constant speed" in reference to a blower or electric motor shall mean blowers and/or motors whose speed is not controlled to control the pressure or flow of therapeutic gas exiting the blower. As between a fully loaded condition of the blower (providing substantially full therapeutic gas flow) and an unloaded condition of the blower (providing substantially no therapeutic gas flow) there may be speed changes, particularly in the case of alternating current (AC) motors. However, speed changes of the motor and/or blower caused by loading and/or unloading of the blower by operation of control valves either upstream or downstream shall not diminish the "constant speed" character of the blower.

DETAILED DESCRIPTION

The following discussion is directed to various embodiments. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure is limited to that embodiment. Figure 1 illustrates a positive airway pressure device 100 in accordance with at least some embodiments. The positive airway pressure device 100 comprises both electrical components and mechanical components. In order to differentiate between electrical connections and mechanical connections, Figure 1 illustrates electrical connections between components with dashed lines, and fluid connections (e.g., tubing connections between devices) with solid lines. The positive airway pressure device 100 in accordance with at least some embodiments comprises a processor 10. The processor 10 may be a microcontroller, and therefore the microcontroller may be integral with read-only memory (ROM) 12, random access memory (RAM) 14, a digital-to-analog converter (D/ A) 16, and an analog-to-digital converter (AJO) 18. The processor 10 may further comprise a communications logic 20, which allows the positive airway pressure device 100 to communicate with external devices (e.g., compliance reporting). In alternative embodiments the processor 10 may be implemented as a standalone central processing unit in combination with individual RAM, ROM, communications, D/A and A/D devices. The ROM 12 stores instructions executable by the processor 10. In particular, the

ROM 12 comprises a software program that implements the individual control of pressure and/or flow to each breathing orifice (e.g., each naris, or the nose as a whole and the mouth). The RAM 14 may be the working memory for the processor 10, where data may be temporarily stored and from which instructions may be executed. Processor 10 may couple to other devices within the system by way of the A/D converter 18 and the D/A converter 16.

The positive airway pressure device in accordance with various embodiments also comprises a single fan or blower 22. Blower 22 may be any suitable device, such as a vane-type blower, coupled to an electric motor 24. Therapeutic gas (e.g., air) provided by the blower 22 is split into two streams, one stream coupled to a first outlet port 23, and a second stream coupled to a second outlet port 25. With regard to the upper stream, the therapeutic gas may flow through a flow sensor 26 (of any suitable type) and a pressure sensor 28 (of any suitable type). Likewise with regard to the lower stream, the therapeutic gas may thus flow through a flow sensor 30 (of any suitable type) and a pressure sensor 32 (of any suitable type). The therapeutic gas pressure and flow then couple to a breathing orifice of the patient (e.g., the patient's nares), where all or substantially all the therapeutic gas inhaled by the patient is supplied from the blower 22. In some embodiments, the therapeutic gas flows through a flow conditioning apparatus to heat and/or humidify the therapeutic gas. So as not to unduly complicate the discussion, the various embodiments discussed from this point forward assume, without limitation, that the breathing orifices to which the streams are provided are the nares individually.

In accordance with the various embodiments, the positive airway pressure device 100 provides positive airway pressure (even if the primary control parameter for the device 100 is therapeutic gas flow) at least during inhalation of the patient, the flow and/or pressure to reduce sleep-disordered breathing such as snoring, hypopnea and/or apnea events. Individual control of the flow and/or pressure of therapeutic gas delivered to each naris by the positive airway pressure device may take many forms. First consider embodiments where the blower 22 is operated at a constant speed by the motor 24. In some embodiments individual control of the pressure and flow to each naris is provided by the control valves 34 and 36. In particular, each valve 34 and 36 has an operator assembly 35 and 37, respectively, that couples to the processor 10 such that the processor 10 controls the therapeutic gas flow through the valve. In this way, and in these embodiments, the pressure and/or flow of therapeutic gas provided to each naris during inhalation are controlled by the respective valves 34 and 36. During exhalation, the gas exhaled by the patient escapes the flow circuit illustrated in

Figure 1 in at least two ways. First, each positive airway pressure mask has a calibrated leak. The calibrated leak allows some portion of the therapeutic gas to vent to atmosphere, but during exhalation also allows gasses exhaled to vent to atmosphere. Second, some of the exhaled gas reverse flows through the flow sensors 26 and 30, valves 34 and 36 and blower 22 to vent to atmosphere through an inlet of the blower. With respect to periods of time when patient respired flow is low (i.e., transitioning from inhalation to exhalation, and transitioning from exhalation to inhalation), if different pressures are applied to the nares, a phenomenon termed here as "crossover" occurs. In particular, if the pressure applied to one naris is higher than the pressure applied to the second naris during a transition, therapeutic gas tends to flow in one naris, crossover in the oral cavity behind the nose, flow out the second naris, and then flow to atmosphere through at least the mask vent. Such crossover may cause irritation in the oral cavity behind the nose. In order to reduce the possibility of crossover in the embodiments illustrated in Figure 1, at least during the transitions periods the pressure applied to each naris is controlled to be substantially the same by positioning valve members of the control valves 34 and 36 at the same valve position (e.g., a predetermined position, or fully open).

In some embodiments, the pressures provided to each naris are substantially constant throughout the respiratory cycle; however, in other embodiments the pressures provided to each naris are reduced during exhalation (e.g., to reduce the effort needed to exhale). In embodiments where the pressure is reduced during exhalation, the reduction in pressure may take place by operation of control valves 34 and 36. Yet still other embodiments comprise dump valves 38 and 40, one dump valve each on each stream. As the name implies, the dump valves 38 and 40 are used to vent pressure within each stream to atmosphere. Each dump valve 38 and 40 has an operator assembly 39 and 41, respectively, that couples to the processor 10 such that the processor 10 controls the flow through the valve. In the embodiments illustrated in Figure 1 with a constant speed blower 22, lowering pressure during exhalation may therefore take place by opening the dump valves 38 and 40, or by a combination of fully or partially closing the control valves 34 and 36 and opening the dump valves 38 and 40. The control valves 34 and 36, as well as the dump valves 38 and 40, may take any suitable form. In some embodiments, the valves are motor operated butterfly or ball valves. In other embodiments, the valve action may take place by selective pinching of a pliable hose. Figures 2A and 2B illustrate valves constructed of pliable hose. In particular, such valves comprise a pliable hose portion 42 (e.g., a flexible rubber hose) in operational relationship to an eccentric cam shaft 44 having an axis of rotation 46 perpendicular to the page. By selective rotation of the eccentric cam shaft 44 (e.g., by a motor operator), the pliable hose 42 is pinched, performing a valve function. Thus, the pliable hose-type valve may be used as any of the control valves 34 and 36 or the dump valves 38 and 40.

The various embodiments illustrated by Figure 1 to this point have been discussed in relation to the blower and motor operating at a constant speed. In other embodiments, the blower speed may be selectively controlled by the processor 10. Figure 1 illustrates a motor speed control circuit 48 coupled between the processor 10 and the motor 24. The motor speed control circuit selectively controls the motor 24 speed, and therefore the blower 24 speed, based on commands from the processor 10. The motor speed control circuit may take many forms. In embodiments where the motor 24 is a direct current motor (DC), the motor speed control circuit provides either a variable voltage DC drive voltage, or a pulse-width modulated drive voltage, or both. In embodiments where the motor 24 is an AC motor, the motor speed control circuit 48 provides a variable frequency drive signal to the motor to control the motor 24 speed.

Control of the pressure and flow of therapeutic gas to each naris is, in embodiments shown in Figure 1 having a variable speed motor/blower, based on a combination of blower 22 speed and control valve 34 and 36 positional settings. For example, during inhalation the control valve for the naris needing higher pressure (i.e., the naris having higher narial resistance to airflow) fully opens, and the motor speed ramps until the desired therapeutic gas flow is achieved. Simultaneously, the second control valve partially closes or pinches to limit pressure and flow provided to the second naris. For embodiments where applied pressure during exhalation is reduced, the reduced pressure could be based on lowering blower 22 speed. In yet still other embodiments, the blower 22 speed is controlled, but also dump valves 38 and 40 are used, and any combination of control valve positioning, blower speed, and dump valve positioning may be used to control applied pressure and flow.

The illustration of Figure 1 is complicated in that Figure 1 shows both electrical and fluid connections. So as not to unduly complicate the presentation of various alternative embodiments, a shorthand notation is adopted. To that end, Figure 3 is a simplified version of Figure 1 with the electrical connections and components removed to illustrate a shorthand notation for the embodiments of Figure 1. In particular, Figure 3 shows blower 22, with the constant speed and variable speed configurations illustrated as CS and VS, respectively, along with control valves 34 and 36 and optional dump valves 38 and 40. Using the shorthand notation from this point forward, the specification now turns to various alternative embodiments. Figure 4 illustrates embodiments using a dump valve 60 positioned between the outlet of the blower 22 and the control valves 34 and 36. Consider first embodiments as in Figure 4 using a constant speed blower. In embodiments using a constant speed blower 22 the dump valve 60 aids in pressure control during inhalation by selectively venting therapeutic gas flow from the blower. Likewise during exhalation, the dump valve 60 may selectively vent therapeutic gas from the blower 22 to help control applied pressure during exhalation, particularly in embodiments where pressure applied during exhalation is reduced. Now consider embodiments as in Figure 4 where a variable speed blower 22 is used. In the variable speed blower 22 embodiments of Figure 4, the dump valve 60 may aid in pressure control during inhalation by selectively venting therapeutic gas during pressure excursions (i.e., overshoot in pressure caused by speed control circuit tuning shortcomings). During exhalation, in addition to blower 22 speed reductions, the dump valve may selectively vent therapeutic gas from the blower 22 to help control applied pressure, particularly in embodiments where the response time of the blower 22 speed is slow in relation to respiration rate and/or where pressure applied during exhalation is reduced. The various embodiments discussed to this point use individual control valves on each of the flow circuits coupled to the outlet ports (and in some embodiments, the nares individually). In other embodiments, the functionality of the control valves 34 and 36 are embodied in a single valve. In particular, Figure 5 illustrates (in the shorthand notation) embodiments comprising a variable speed blower 22 fluidly coupled to an inlet 64 of the control valve 62. Illustrative control valve 62 further comprises two outlet ports 66 and 68 that couple one each to the outlet ports of the overall device, ports 23 and 25 respectively. In accordance with embodiments using control valve 62, therapeutic gas flow provided by blower 22 is selectively proportioned to one of the first and second outlet ports 23 and 25. In particular, the illustrative valve 62 comprises rotationally moveable valve member (discussed more below) that, depending on rotational orientation, selectively diverts therapeutic gas flow from the blower 22 to the outlet ports 23 and 25.

Before turning to the specifics of at least some embodiments of the control valve 62, alternative arrangements of a device using the control valve 62 are discussed. For example, Figure 6 illustrates embodiments where the control valve 62 is used in combination with a dump valve 60. In particular, Figure 6 shows blower 22 fluidly coupled to the control valve 62, which control valve 62 in turn fluidly couples to the outlet ports 23 and 25. Dump valve 60 fluidly couples to the fluid connection between the blower 22 and the control valve 62, and selectively vents therapeutic gas to atmosphere. Much like the embodiments discussed with respect to Figure 4, the dump valve 62 enables use of a constant speed blower 22, or may be used with a variable speed blower 22 to aid in pressure control and/or to (at least in part) enable reduced pressure during exhalation by selective venting of therapeutic gas.

Figure 7 illustrates yet still further embodiments where each therapeutic gas flow stream between the control valve 62 and the outlet ports 23 and 25 comprises a dump valve 38 and 40, respectively. Dump valves 38 and 40 selectively vent therapeutic gas to atmosphere. Much like the embodiments discussed with respect to Figure 3, the dump valves 38 and 40 enable use of a constant speed blower 22, or may be used with a variable speed blower 22 to aid in pressure control and/or to (at least in part) enable reduced pressure during exhalation by selective venting of therapeutic gas. The various embodiments discussed to this point are based on use of either a constant speed blower 22 or a variable speed blower 22. In yet still further embodiments, any of the various arrangements discussed utilizing a variable speed blower 22 may instead use a constant speed blower 22 in combination with a throttle valve 69, as illustrated in Figure 8A (in the shorthand notation, and in reference to the illustrative arrangement of Figure 5). In particular, the device of Figure 8 A comprises a throttle valve 69 fluidly coupled to the inlet of the blower 22. The blower 22 fluidly couples to the control valve 62, which in turn fluidly couples to the outlet ports 23 and 25. Under control of the processor 10, the throttle valve 69 selectively controls an amount of therapeutic gas (e.g., air) entering the blower 22. Given the relatively constant speed of the blower 22, the pressure and/or flow of therapeutic gas exiting the blower 22 may thus be controlled by positioning of a valve member within throttle valve 69. In yet still further alternative embodiments illustrated in Figure 8B, the throttle valve 69 may fluidly couple to the outlet of the blower 22, between the blower 22 and the illustrative control valve 62. While either orientation of the throttle valve is operable, the inventors of the current specification have found that less audible noise is produced if the throttle valve is positioned on the inlet of the blower 22. The specification now turns to various embodiments of the control valve 62.

Figure 9 illustrates an overhead view of at least some embodiments of control valve 62. In particular, the control valve 62 contains an outer housing 70. The outer housing 70 comprises three ports: an inlet port 72; and two outlet ports 74 and 76. Therapeutic gas from blower 22 (not shown in Figure 9) couples to the control valve inlet port 72. The control valve 62 then selectively divides or proportions the therapeutic gas between the outlet ports 74 and 76. The illustrative mechanism by which the proportioning takes place is shown in Figures 1OA and 1OB. Figures 1OA and 1OB are overhead views of control valve 62 with the top portion of the outer housing 70 removed to show the relationship of the moveable valve member 78 to the various inlet and outlet ports. In particular, within the outer housing 70 is a moveable valve member 78 that comprises a flow diversion portion 80 and a two blocking portions 82 and 84 held between upper and lower disc members (the disc member visible in the view of Figures 1OA and 1OB is illustrated as clear to make the diversion and blocking portions visible). The moveable valve member 78 is rotationally coupled within the outer housing 70 to enable different orientations of the diversion portion 80 and blocking portions 82 and 84 with respect to the inlet and outlet ports. In the orientation of the moveable valve member 78 shown in Figure 1OA, the leading edge of the flow diversion portion 80 is centered with respect to the inlet port 80. Likewise in the orientation of the moveable valve member Figure 1OA, the blocking portions 82 and 84 do not block therapeutic gas flow into their respective outlet ports. As a device within which control valve 62 is located senses an imbalance of therapeutic gas flow to the nares, the moveable valve member 78 is rotated (discussed more below) in an attempt to evenly distribute the therapeutic gas flow. In accordance with at least some embodiments, the distribution of therapeutic gas flow has two components: a diversion portion; and a blocking portion. The diversion portion of the distribution of the therapeutic gas flow is enabled by the diversion portion 80. With the moveable valve member 78 in a non-centered orientation, such as in Figure 1OB, the diversion portion 80 makes the flow path to one of the outlet ports 74 and 76 more fluid dynamically preferred. Stated otherwise, the diversion portion 80 rotated to favor one outlet port 74, 76 creates flow pathway that has fewer impediments to therapeutic gas flow, and thus less pressure drop occurs along the flow pathway. In the illustrative orientation of Figure 1OB, the moveable valve member 78 is rotated to create a fluid dynamically preferred flow path to outlet port 74. It is noted, however, that in at least some embodiments in spite of the fact that the moveable valve member 78 is rotated, that therapeutic gas flow as between the outlet ports 74 and 76 is substantially evenly distributed. Thus, because of the resistance to therapeutic gas flow downstream of the control valve 62 (e.g., at the patient's nares), the therapeutic gas flow through each outlet port 74 and 76 may be substantially the same in spite of the orientation of the moveable valve member 78 (though the absolute pressure within each outlet port will be different).

The second aspect of distribution is the blocking portion. In accordance with at least some embodiments, the blocking aspect of distribution is enabled by the blocking portions 82 and 84 of the moveable valve member 78. As the moveable valve member 78 rotates within the outer housing 70, at least one of the blocking portions 82 and 84 rotate to block the respective outlet port. In the illustration of Figure 1OB, blocking portion 82 is shown to partially block outlet port 76 while blocking portion 82 moves further away from its outlet port 74. Again, in at east some embodiments the therapeutic gas flow through each outlet port 74 and 76 are substantially the same, but the blocking portions 82 and 84, when occluding their respective outlet ports, provide additional flow impediments to cause pressure drop along the non-preferred flow pathway. Before proceeding, it should be understood that the neither the blocking portions 82 and 84 nor the flow division portion 80 are required. A system with a control valve 62 having only one set of pressure/flow control elements would still be operational; however, the inventors of the current specification have found that the range of differential pressures as between the nares which can be created when having both a diversion portion and a blocking portion are greater than control valves having just one of these components alone.

Figure 11 shows an elevation side view of the control valve 62 and a valve movement operator 90 in accordance with at least some embodiments. In particular, in some embodiments the orientation of the moveable valve member 78 is controlled without direct physical contact between the valve member 78 and the stepper motor 92. In embodiments without direct physical contact, the shaft 94 of the stepper motor 92 couples to a disk 96 having a magnet 98 affixed on an outer edge. Referring briefly to Figure 1OA, within the outer housing 70 the moveable valve member 78 likewise has a magnet 100 (shown in dashed lines to signify that the magnet resides on a bottom side of a lower disk portion of the valve member 78, and thus is not in the therapeutic gas flow path). The magnet 100 on the valve member 78 magnetically couples to the magnet 98 on the disk 96 coupled to the stepper motor. Thus, the stepper motor controls the rotational position of the moveable valve member 78 by turning disk 96. The magnetic force between the two magnets 98 and 100 in turn forces the moveable valve member 78 to a corresponding location. Having the valve member 78 magnetically coupled to the disk 98 and stepper motor 92 reduces valve control sounds detectable by the patient through mask, reduces the number of apertures through the outer housing 70, and also reduces potential toxicity of the control valve 62 by reducing the need for seals and bearings having hydrocarbon-based lubricants. In other embodiments, the shaft 94 of the stepper motor 92 extends through the outer housing 70 and directly couples to the moveable valve member 78.

Still referring to Figure 11, in at least some embodiments it is beneficial for the processor 10 (Figure 1) to have a direct indication of the rotational orientation of the moveable valve member 78. In embodiments using magnetically coupled valve member 78 and disk 96, position of the valve member 78 may be sensed from a second disk 97 mechanically coupled to the moveable valve member 98 by way of shaft 99. In particular, illustrative disk 97 has associated therewith a position sensing circuit 102. In the embodiments illustrated in Figure 11, the position sensing is by way of optical sensing, but in other embodiments other types of sensing may be used (e.g., detents in the disk sensed by mircoswitches, Hall effect sensors and associated magnets). Figure 12 shows an overhead view of disk 97 in order to discus the sensing of the rotational orientation of the disk 97 (and thus the valve member 78). In particular, disk 97 has a plurality of apertures at 104 varying diameters. In accordance with these embodiments, three optical sensors are used, one each at each of the varying diameters. When the disk 97 is aligned with optical sensors at location 106, all three optical sensors sense the light source, and with sensing light arbitrarily assigned Boolean value of one, when the disk 97 is aligned with the optical sensors at location 106, an illustrative Boolean value of "111" is sensed. As the disk 97 rotates (because of rotation of valve member 98), differences in the apertures are sensed. For example, when the disk 97 turns such that the optical sensors are in zone 108, an illustrative Boolean value of "010" is sensed. Likewise, when the disk 97 turns such that the optical sensors are in zone 110, an illustrative Boolean value of "001" is sensed. When the disk 97 turns to a full diverting/blocking deflection of the valve member 78 in a first direction, optical sensors align with location 112, and an illustrative Boolean value of "110" is sensed. Likewise, when the disk 97 turns to a full diverting/blocking deflection of the valve member 78 in a second direction, optical sensors align with location 114, and an illustrative Boolean value of "Oi l" is sensed. Thus, the processor 10 is enabled to sense the orientation of the disk 97 (and thus the valve member 78). In alternative embodiments, fewer or greater numbers of sensors (e.g., two) may be equivalently used.

Figure 13 illustrates a control methodology implemented by the processor 10 (Figure 1) in accordance with at least some embodiments. The illustrative method is discussed in reference to embodiments using control valve 62; however, after understanding the control methodology in reference to the control valve 62, the methodology is extendable to systems using separate valves 38 and 40 on each control path. In particular, the method starts (block 1300) with the valve member 78 of the control valve 62 centered and therapeutic gas pressure set to a predetermined value (e.g., prescribed titration pressure). The illustrative process waits until a first inhalation is sensed (block 1302), and when the first inhalation is sensed the illustrative process proceeds along two parallel paths. Skipping for now blocks 1304 and 1306, the illustrative process simultaneously adjusts the pressure of the therapeutic gas flow for the naris exhibiting less resistance to therapeutic gas flow (i.e., the non-burdened naris) (block 1308) while adjusting the position of the moveable valve member 78 of the control valve 62 to substantially equalize therapeutic gas flow (block 1310). In some embodiments, assigning a burdened or non-burdened control status to each naris is based on software determination observing therapeutic gas flows and pressures. In other embodiments, the position sensing with respect to disk 98 indicates directly the burdened and non-burdened naris. The valve member 78 of the control valve 62 adjusts to increase pressure to the naris exhibiting greater resistance to therapeutic gas flow (i.e., the burdened naris). If only the valve member 78 position is adjusted, the pressure of the therapeutic gas provided to the non- burdened naris drops. In order to compensate for reduced pressure cause by valve member 78 position changes, therapeutic gas provided from the blower 22 is increased. Thus, while the controlled parameters (therapeutic gas pressure from the blower 22 and valve member 78 position) are interdependent, generalizing for the sake of clarity the therapeutic gas pressure provided by the blower 22 is adjusted to control the pressure to the non-burdened naris, while the position of the valve member 78 is adjusted to balance of therapeutic gas flow to the nares.

Adjusting the therapeutic gas pressure from blower 22 may take many forms, as discussed above. In some embodiments, a variable speed motor/blower is used, and thus changes in therapeutic gas pressure provided from the blower 22 are made by speed changes. In other embodiments, the blower 22 operates at a constant speed, and the therapeutic gas pressure provided may be adjusted by control of a throttle valve 69 and/or dump valve 60. In yet still other embodiments, the therapeutic gas pressure provided by the blower 22 may be adjusted by a combination of any of the aforementioned control mechanisms. With respect to adjusting valve member 78, in some embodiments the position of the valve member 78 is adjusted throughout the inhalation, while in other embodiments the position of the valve member 78 is only adjusted for a portion of the inhalation (e.g., the first quarter of the inhalation and thereafter the valve remains at the last controlled position). In situations where valve member 78 position is only adjusted for a portion each inhalation, several respiratory cycles may be traversed before achieving a substantially equal distribution of therapeutic gas flow as between the nares.

Returning to Figure 13, the illustrative method continues to adjust therapeutic gas pressure (block 1308) and continues to have the ability to adjust valve member 78 position (block 1310), even if the system elects not to adjust after a predetermined period of time, until exhalation is sensed (block 1312). When the exhalation is sensed, the system saves the last valve member 78 position, the last therapeutic gas pressure setting, and centers the valve member 78 (block 1314). Saving the last valve member 78 position and the last therapeutic gas pressure setting enables the control methodology illustrated by Figure 13 to return to the last known good settings on the next inhalation. Centering the valve member 78 position ensures that crossover between the nares does not occur, as discussed above. Skipping for now block 1316, the illustrative method continues until an inhalation is sensed (block 1318), and then proceeds again to the control methodology described with respect to inhalation (blocks 1308 and 1310). However, on second and subsequent entries to the parallel paths of the illustrative method, the valve member 78 position is placed at the last known good position (block 1306) saved in block 1314. To the extent the last know valve member 78 position is close to the position that provides substantially equalized therapeutic gas flow as between the nares, moving the valve member 78 position to the last know good position increases responsiveness of the therapeutic gas flow control loop.

In alternative embodiments, the therapeutic gas pressure applied during exhalation is not the same as that applied during inhalation. Returning to block 1314, in alternative embodiments, after centering the valve member 78 in response to sensing an exhalation the therapeutic gas pressure is reduced (block 1316). Reducing the therapeutic gas pressure may take many forms. In some embodiments, a variable speed motor/blower is used, and thus reducing in therapeutic gas pressure provided from the blower 22 is made by lowering blower speed. In other embodiments, the blower 22 operates at a constant speed, and the therapeutic gas pressure provided lowered by control of a throttle valve 69 and/or dump valve 60. In other embodiments, the therapeutic gas pressure provided by the blower 22 is lowered by opening dump valves 38 and 40 on the respective flow pathways. In yet still other embodiments, the therapeutic gas pressure provided by the blower 22 is lowered by a combination of any of the aforementioned control mechanisms. Once an inhalation is sensed (again block 1318), in the pressure control portion of the parallel pathways the therapeutic gas pressure is increased to last know good pressure setting (block 1304) stored in block 1314.

The various embodiments of the device 100 of Figure 1 have pressure sensors 28 and 32. The pressure sensors 28 and 32 provide pressure readings to the processor 10 referenced to atmosphere (or possibly absolute pressure). Because of the pressure reference, and because the device 100 has the ability to dynamically control applied therapeutic gas pressure, device 100 can use a permanent or removable blower inlet air filter without adversely affecting device performance. In particular, Figure 14 illustrates a device 100 in accordance with alternative embodiments (in the shorthand notation) having a blower inlet air filter 120. The blower inlet air filter 120 may take many forms. In some embodiments, the blower inlet air filter 120 is a high efficiency particular air (HEPA) filter which removes 99.99% of airborne particles having diameters of 0.3 micrometers or greater. In other embodiments, the blower inlet air filter 120 is a ultra low penetration air (ULPA) filter which removes 99.9995% of airborne particles having diameters of 0.12 micrometers or greater. Thus, while filter 120 may present a resistance to therapeutic gas flow into the blower 22 and corresponding reduction in pressure provided by the blower 22, the corresponding reduction in pressure can be determined by pressure sensors 28 and 32, and compensated for by control action associated with the blower (e.g., increasing blower speed).

Figure 14 also illustrates alternative embodiments (in the shorthand form) where the therapeutic gas supplied by the blower 22 (e.g. , air) is supplemented by another therapeutic gas (e.g., oxygen, helium). In particular, a second source of therapeutic gas 122 fluidly couples to a gas inlet port 125 that fluidly couples to the fluid connection between the blower 22 and control valve 62 by way of a valve 124. Inasmuch as therapeutic gas flow as between outlet ports 23 and 25 are substantially equal during inhalation in some embodiments, gas from the second therapeutic gas source is likewise substantially equally divided between the two outlet ports 23 and 25. In some embodiments, the second therapeutic gas source 122 provides gas during both inhalation and exhalation, but in other embodiments valve 124 (e.g. a solenoid valve) turns off the second therapeutic gas source during exhalation.

Finally, the inventors of the present specification have found that the therapeutic gas exiting the blower 22 is non-laminar flow, and in some cases the non-laminar flow exhibits a gas swirl about the axis of travel. The gas swirl may cause inconsistent dividing or proportioning of the therapeutic gas flow by illustrative control valve 62. In order to address the non-laminar flow, and as illustrated in Figure 14, some embodiments implement a flow straightening device 130 within the therapeutic gas flow downstream of the of the blower 22. The flow straightening device may take the form of a plurality of parallel plates within therapeutic gas flow, or in other embodiments an extended straightener having a honeycomb cross-section.

The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become to those skilled in the art once the above disclosure is fully appreciated. For example, while in some embodiments the therapeutic gas supplied to each naris is controlled to be substantially equal, in other embodiments the therapeutic gas flow provided to each naris is controlled to be different (e.g., where an anatomical blockage allows some therapeutic gas flow, but where substantially equal flow causes irritation). It is intended that the following claims be interpreted to embrace all such variations and modifications.

Claims

CLAIMS What is claimed is:

1. A system comprising: a first outlet port configured to couple to a first breathing orifice of a patient; a second outlet port configured to couple to a second breathing orifice of a patient; a single blower fluidly coupled to the first outlet port and the second outlet port, the single blower provides substantially all the therapeutic gas inspired through the first and second breathing orifices; and a first valve fluidly coupled between the single blower and the first outlet port; said system configured to control pressure of therapeutic gas applied to the first outlet port to be different than pressure of therapeutic gas applied to the second outlet port.

2. The system as defined in claim 1 wherein the first valve also fluidly couples between the single blower and the second outlet port.

3. The system as defined in claim 2 wherein first valve further comprises a moveable valve member coupled to a stepper motor by at least one selected from the group consisting of: a direct mechanical connection to a shaft of the stepper motor; and a magnetic coupling to the shaft of the stepper motor.

4. The system as defined in claim 1 further comprising a second valve fluidly coupled between the single blower and the second outlet port.

5. The system as defined in claim 4 wherein the first valve comprises: a pliable hose portion; and an eccentric cam shaft that selectively pinches the pliable hose portion.

6. The system as defined in claim 4 further comprising at least one selected from the group consisting of: the single blower operates at a constant speed; and the single blower operates at variable speeds.

7. The system as defined in claim 1 further comprising a throttle valve fluidly coupled to an inlet of the single blower, the throttle valve selectively blocks therapeutic gas exiting the single blower.

8. The system as defined in claim 1 further comprising a throttle valve fluidly coupled between an outlet of the single blower and the first valve, the throttle valve selectively blocks therapeutic gas exiting the single blower.

9. The system as defined in claim 1 further comprising a gas inlet port configured to fluidly couple to a source of therapeutic gas, the gas inlet port fluidly coupled to an outlet of the blower.

10. The system as defined in claim 1 further comprising: a second valve fluidly coupled to the single blower, and the second valve configured to dump to atmosphere; said second valve selectively releases at least a portion of the therapeutic gas from the blower to atmosphere.

11. The system as defined in claim 1 further comprising: a first dump valve fluidly coupled to the first outlet port, the first dump valve selectively releases at least a portion of the therapeutic gas from the single blower to atmosphere; and a second dump valve fluidly coupled to the second outlet port, the second dump valve selectively releases at least a portion of the therapeutic gas from the single blower atmosphere.

12. The system as defined in claim 11 further comprising at least one selected from the group consisting of: the single blower operates at a constant speed; and the single blower operates at variable speeds.

13. The system as defined in claim 1 wherein the first outlet port is configured to couple to the first breathing orifice being a first naris of the patient, and the second outlet port is configured to couple to the second breathing orifice being a second naris of the patient.

14. The system as defined in claim 1 wherein the first outlet port is configured to couple to the first breathing orifice being a nose of the patient, and the second outlet port is configured to couple to the second breathing orifice being a mouth of patient.

15. The system as defined in claim 1 further comprising: said single blower comprising an inlet and an outlet, the outlet fluidly coupled to the to the first valve; an air filter coupled to the inlet of the single blower, and therapeutic gas that enters the inlet of the single blower passes through the air filter.

16. The system as defined in claim 1 further comprising a gas flow straightening device coupled between the single blower and the first valve.

17. A method comprising: operating a single blower of a positive airway pressure device to produce a therapeutic gas stream, substantially all the gas inhaled by a patient is provided by the single blower; providing a first portion of the therapeutic gas stream to a first outlet port at a first pressure, the first outlet port to couple to a first breathing orifice of a patient; and providing a second portion of the therapeutic gas stream to a second outlet port at a second pressure different than the first pressure, the second outlet port to couple to a second breathing orifice of a patient;

18. The method as defined in claim 17 further comprising increasing the first pressure during an inhalation while maintaining the second pressure during the inhalation.

19. The method as defined in claim 18 wherein increasing the first pressure further comprises restricting therapeutic gas flow to the second outlet port and increasing speed of the single blower.

20. The method as defined in claim 17 further comprising: wherein providing the first portion further comprises providing the first portion to a first naris of the patient during an inhalation; and wherein providing the second portion further comprises providing the second portion to a second naris of the patient during the inhalation.

21. The method as defined in claim 20 further comprising providing the therapeutic gas at the same pressure to each naris during an exhalation immediately subsequent to the inhalation.

22. The method as defined in claim 21 wherein providing the therapeutic gas at the same pressure during the exhalation further comprises providing the therapeutic gas at a reduced pressure.