Patent Publication Number: US-10314991-B2

Title: Breathing apparatus and method for the use thereof

Description:
This application is a continuation of International Application No. PCT/IB2014/000363, filed Mar. 14, 2014, which claims the benefit of U.S. Provisional Application No. 61/794,824, filed Mar. 15, 2013, the entire disclosure of which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to an apparatus for administering respiratory therapy, including, without limitation, for assisting with breathing, reducing the work of breathing, performing breathing exercises and/or enhancing aerobic capacity, together with methods for the use thereof. 
     BACKGROUND 
     Many types of devices are available to administer respiratory therapy to a user, for example when the user is suffering from chronic obstructive pulmonary disease. Often, it may be desirable to apply a positive pressure during an inhalation sequence so as to assist the user when inhaling. At the same time, it may be desirable to provide positive expiratory pressure (PEP) during exhalation, for example to promote alveolar recruitment, reduce dynamic hyperinflation and prevent small airway and alveolar collapse. Typically, however, such benefits are achievable only through the use of expensive, non-portable equipment such as ventilators, bi-level positive airway pressure systems (BPAP) and/or continuous positive airway pressure systems (CPAPs). In addition, these types of devices typically use external pressure sources, for example supplemental oxygen and compressors, to provide pressure support, making them bulky and non-self sustaining. 
     SUMMARY 
     The present invention is defined by the claims, and nothing in this section should be considered to be a limitation on those claims. 
     In one aspect, a breathing apparatus includes an inner volumetric member pressurizable from a first pressure to a second pressure and an outer volumetric member surrounding at least a portion of the inner expandable volumetric member. The inner volumetric member pressurizes the outer volumetric member as the inner volumetric member is pressurized from the first pressure to the second pressure. An expiratory flow path communicates with the inner volumetric member. A one-way exhalation valve communicates with the inner volumetric member at a location spaced from the expiratory flow path. An inspiratory flow path communicates with the outer volumetric member, and an intake portal communicates with the outer volumetric member. 
     In another aspect, a breathing apparatus includes an exhalation chamber having a first biasing member dividing the chamber into first and second variable chambers. The first variable chamber includes an inlet port adapted for fluid communication with a user interface and an outlet port. The second variable chamber includes an inlet port and an outlet port. An inhalation chamber includes an inlet port in fluid communication with the outlet port of the second variable chamber, an outlet port in fluid communication with the user interface, and a second biasing member. The first biasing member is moveable from a first position to a second position in response to an exhaust flow from the inlet port of the first variable chamber, such that a volume of the first variable chamber is increased from a first volume to a second volume and a volume of the second variable chamber is decreased from a first volume to a second volume in response to the movement of said first biasing member. The second biasing member is moveable from a first position to a second position in response to a pressurized flow from the outlet port of the second variable chamber to the inlet port of the inhalation chamber. A volume of the inhalation chamber is increased from a first volume to a second volume in response to the movement of the second biasing member. 
     A method of assisting the breathing of a user includes exhaling through an expiratory flow path into an inner volumetric member, increasing a pressure of an exhaled gas inside the inner volumetric member, applying a pressure against an outer volumetric member with the inner volumetric member, releasing exhalation gases from the inner volumetric member, and inhaling through an inspiratory flow path from the outer volumetric member. 
     In another aspect, a method of assisting the breathing of a user includes exhaling an exhaled gas into an exhalation chamber divided by a first biasing member, applying a pressure to a first side of the first biasing member with the exhaled gas and moving the first biasing member in a first direction, applying a pressure with a second side of the first biasing member to an inhalable gas, applying a pressure to a first side of a second biasing member in an inhalation chamber with the inhalable gas, and inhaling the inhalable gas from the inhalation chamber while applying a pressure to the inhalable gas with the second biasing member. 
     The apparatus and method of use are configured to manually assist a user&#39;s breathing, in particular users who may suffer from chronic obstructive pulmonary disease. The apparatus provides some resistance to exhalation which is helpful in keeping the small airways open and in expanding the collapsed or partly collapsed alveoli. On inhalation, there is a build-up of pressure that takes place during a preceding exhalation maneuver, causing air trapped in a volumetric member to flow to the user, or patient. During inhalation, ambient air may be entrained into the flow path via inhalation ports. In this way, the apparatus assists breathing during inhalation by providing positive pressure, but also provides positive expiratory pressure during exhalation (PEP). The apparatus may also be used for manual inhalation assistance to assist with the work of breathing (inhalation/exhalation) or for manual ventilation. At the same time, the device may include one or more filters for removing impurities and microbes thereby improving air quality. Those filters may incorporate or be covered with substances that may be vaporized or sublimated. The device may also allow for warming or preheating of inhalation gases along with humidification of the inhalation gases. 
     The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The various preferred embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of the breathing assistance apparatus during an exhalation sequence. 
         FIG. 2  is a schematic cross-sectional view of the breathing assistance apparatus during an inhalation sequence. 
         FIG. 3  is a cross-sectional view of one embodiment of an exhalation valve in a closed position. 
         FIG. 4  is a cross-sectional view of the exhalation valve in an open position. 
         FIGS. 5A-F  show the operations of another embodiment of a breathing assistance apparatus. 
         FIG. 6  is a perspective view of another embodiment of a breathing assistance apparatus. 
         FIG. 7  is a schematic of a breathing assistance apparatus. 
         FIGS. 8A  and B show top and bottom perspective view of another embodiment of a breathing assistance apparatus. 
         FIG. 9  is a plan view of the components incorporated in the breathing assistance apparatus shown in  FIGS. 8A  and B. 
         FIGS. 10A-C  shown an adjustable exhalation chamber. 
         FIG. 11  is a graph comparing the inhalation pressure of one embodiment of the present device with a spring-piston device. 
         FIGS. 12A-C  show the operation of one embodiment of a mouthpiece configured for the breathing assistance apparatus. 
         FIG. 13  shows an alternative embodiment of a mouthpiece. 
         FIGS. 14A-B  show the operation of one embodiment of a peak pressure and peep valve for use in the breathing assistance apparatus. 
         FIGS. 15A-B  show the operation of an alternative embodiment of a peak pressure and peep valve. 
         FIGS. 16A-B  show a diaphragm used in the valve of  FIGS. 15A  and B. 
         FIGS. 17A-B  show an alternative embodiment of a peak pressure and peep valve. 
         FIGS. 18A-B  show an alternative embodiment of a peak pressure and peep valve. 
         FIGS. 19A-B  show a diaphragm used in the valve of  FIGS. 18A  and B. 
         FIG. 20  is an exploded view of the valve shown in  FIGS. 15A  and B. 
         FIG. 21  is an exploded view of the breathing assistance apparatus shown in  FIGS. 5A-F . 
         FIG. 22  is an exploded view of the valve shown in  FIGS. 18A  and B. 
         FIG. 23  is an exploded view of an alternative embodiment of a peak pressure and peep valve. 
         FIG. 24  is an exploded view of the breathing assistance apparatus shown in  FIGS. 8A-9 . 
         FIG. 25  is an alternative embodiment of a breathing assistance apparatus. 
         FIG. 26  is an alternative embodiment of a breathing assistance apparatus. 
         FIG. 27  shows a pressure relief valve arrangement used in the embodiment of  FIG. 26 . 
         FIGS. 28A-F  and  29  are various schematic views of an alternative breathing assistance apparatus. 
         FIG. 30  is a cross section of an inspiratory and expiratory flow path tubing. 
         FIGS. 31A-C  show an adjustable diaphragm valve. 
         FIG. 32  shows a frame for a peak pressure and PEEP valve. 
         FIGS. 33A  and B show the operation of a valve. 
         FIG. 34  is a side view of the valve shown in  FIG. 32 . 
         FIG. 35  show a control for the valve shown in  FIG. 32 . 
         FIGS. 36A  and B show an alternative embodiment of a breathing assistance device. 
         FIG. 37  shows a valve control embodiment. 
         FIGS. 38A  and B show an embodiment of a breathing assistance device configured with the valve of  FIG. 37 . 
         FIG. 39  is a pressure v. volume graph for one embodiment of a breathing assistance device. 
         FIGS. 40A  and B are schematic views showing a mechanism for emptying a chamber. 
         FIG. 41  shows a schematic view of a three-way valve. 
         FIGS. 42A-C  are schematic views showing a mechanism for emptying a chamber. 
         FIG. 43  is a front view of an alternative with the control stem in an open position. 
         FIG. 44  is a front view of the control stem in a partly closed position. 
         FIG. 45  is a side view of the control stem shown in  FIG. 43 . 
         FIG. 46  is a side view of the control stem shown in  FIG. 44 . 
         FIGS. 47-48  show an embodiment of a breathing assistance device in isometric and cut-away views. 
         FIGS. 49-54B  show cross-sectional views of the device shown in  FIG. 47  in various stages of operation. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
     It should be understood that the term “plurality,” as used herein, means two or more. The term “longitudinal,” as used herein means of or relating to length or the lengthwise direction. The term “lateral,” as used herein, means situated on, directed toward or running from side to side. The term “coupled” means connected to or engaged with whether directly or indirectly, for example with an intervening member, and does not require the engagement to be fixed or permanent, although it may be fixed or permanent. The terms “first,” “second,” and so on, as used herein are not meant to be assigned to a particular component so designated, but rather are simply referring to such components in the numerical order as addressed, meaning that a component designated as “first” may later be a “second” such component, depending on the order in which it is referred. It should also be understood that designation of “first” and “second” does not necessarily mean that the two components or values so designated are different, meaning for example a first valve may be the same as a second valve, with each simply being applicable to different components, and that a first valve may later be referred to as a second valve depending on the order of reference, and vice versa. The term “upstream” refers to a direction opposite the direction of a flow, while the term “downstream” refers to a direction of a flow. Therefore, and for example, a fluid flows downstream from an upstream location to a downstream location. 
     Referring to  FIGS. 1, 2, and 26 , a breathing assistance apparatus includes a patient interface, shown as a mask  2 . In other embodiments, the interface may be configured as a mouthpiece, nasal cannula, mask, or combinations thereof or may include a connector suited for connecting a respiratory tube, such as an endotracheal tube or tracheostomy tube. The interface may include at least one inhalation valve in communication with ambient air. For example, in one embodiment, the mask may be configured with an inhalation valve  21  and an exhalation valve  20 , which may be integrally formed in one embodiment, for example as a duckbill exhalation valve and an annular inhalation valve. In one embodiment, the exhalation valve  20  may be removably connected to an adaptor that is suited for connection to an apparatus used to clean and disinfect the expiratory flow path tubing. Various straps  4 , such as ear loops, may extend from lateral portions of the mask such that it may be secured to a user. The mask covers the nose of the user, and forms a seal with the user&#39;s face. In another embodiment, the mask covers the nose and mouth of the user. The mask may be configured with one or more auxiliary one-way inhalation valves  10  which communicate directly with the ambient environment. The mask may also be configured with an adaptor suited to receive a device intended to monitor inspiratory and/or expiratory pressure. 
     In one embodiment, the patient interface is a nasal cannula that is configured with two cannulas, each suited for insertion into a patient&#39;s nostril. One cannula may be solely suited for expiration and the other for inhalation. Alternatively, each cannula may include two separate flow paths parallel to each other or two separate concentric flow paths with one flow path used as an expiratory flow path and the other as an inspiratory flow path. Each nasal cannula flow path includes a one-way valve to maintain the flow in the flow path in the desired direction. The cannulas may be connected to the expiratory flow path and inspiratory flow path. In one embodiment, the breathing assistance apparatus may include two separate expiratory flow paths and two separate inspiratory flow paths, with each connected to a nasal cannula. 
     The one-way exhalation valve  20  communicates with an expiratory flow path  23 , configured as a tube in one embodiment, upon exhalation by the user. The one-way inhalation valve  21  communicates with an inspiratory flow path  22 , configured as a tube in one embodiment, upon inhalation by the user. The proximal portion  67  of the inspiratory flow path tubing closest to the inhalation valve would not be expandable in one embodiment. In order to reduce inhalation effort, the inhalation valve  21  is provided with a larger surface area than the exhalation valve  20  in one embodiment. Of course, it should be understood that the pressure or flow required to open any valve may be adjusted and predetermined by the design and materials of the valve. The one-way auxiliary inhalation valve(s)  10  open to allow the flow of ambient air if and when the pressure drops to negative values in the inspiratory flow path  22 , with the auxiliary inhalation valve(s)  10  providing the user with an ample supply of air. 
     In one embodiment, the expiratory tubing  23  has an inner diameter of about 5 mm, while the inhalation tubing has an inner diameter of about 15 mm. The expiratory flow path  23 , or tubing, communicates between the valve  20  and a first location, or inlet, on an inner volumetric member  24 , configured in one embodiment as an expandable expiratory balloon or bag. In one embodiment, the expiratory tubing and inner volumetric member may be integrally formed, but each may be made with a material of a different compliance. 
     An outer volumetric member  25  surrounds at least a portion, and in one embodiment the entirety, of the inner volumetric member  24 . In one embodiment, the inner volumetric member is slipped inside the outer volumetric member, which may be resealed. The outer volumetric member  25  may be configured in one embodiment as an expandable inspiratory balloon or bag. In one embodiment, the outer volumetric member  25  has a first volume of about 500 cc when no pressure is being applied thereto. The outer volumetric member  25  may be made of a relatively rigid foam type material that is squeezable by hand, but able to quickly recover a normalized position when released. In one embodiment, the outer volumetric member has a general football shape. One or more intake portals  27  may be located on the outer volumetric member  25 . In one embodiment, the portals are configured with one-way valves that allow one-way flow from the ambient environment into the member  25 . The intake portals  27  are spaced apart from a pressure relief valve  26  such that exhaled gases exiting the valve  26  are not rebreathed through the portal(s)  27 . The outer volumetric member  25  is coupled to the inspiratory flow path  22  such that the member  25  and flow path  22  are in fluid communication. In one embodiment, the outer volumetric member  25  and the inspiratory flow path tube  22  are integrally formed. The outer volumetric member  25  may be provided with straps, buttons, snaps, adhesive or other devices to allow for the apparatus to be secured to the user&#39;s chest or other convenient location. In one embodiment, the inner volumetric member  24  has a volume of up to 100 cc when deflated and a volume of up to 500 cc when inflated. 
     The inner volumetric member  24  has a defined shape memory, and in one embodiment, is configured with a general football shape. In one embodiment, the inner volumetric member  24  is made of an elastic material that expands in response to an increase in air pressure and contracts in response to a decrease in air pressure. Examples of suitable elastic materials include rubber and silicone. The inner volumetric member  24  is coupled to the flow path tube  23  at a first location, whether by way of a connector or by way of an integral, continuous formation, and to the pressure relief valve  26  at a second location spaced from the first location. The pressure relief valve  26  is configured as a pop-up valve in one embodiment. 
     Referring to  FIGS. 3, 4, and 27 , the pressure relief valve  26  includes a narrow magnetic band  40  spaced apart from a non-magnetic band  41 , formed for example from plastic, adjacent an end of the pressure relief valve  26  communicating with the interior volume of the inner volumetric member  24 . The spacing between the bands  40 ,  41  may be varied by a control mechanism  42 . In one embodiment, the control mechanism includes a screw that when rotated in a first direction will increase the spacing between the magnetic band  40  and the non-magnetic band  41  and when rotated in a second direction will decrease the spacing between the magnetic band  40  and the non-magnetic band  41 . A valve head  43  is made of a metal in one embodiment. In a closed position, shown in  FIG. 3 , the valve head  43  rests against a valve seat  41 . The magnetic force  44  between the band  40  and the valve head  43  is determined by the spacing in between, which may be adjusted by the control mechanism  42 . The magnetic force  44  determines the pressure (PEP) required to open the pressure relief valve  26 , or move the valve head  43  away from the valve seat  41 . The positive pressure required to open the pressure relief valve  26  is preferably between 3 cm H 2 O and 30 cm H 2 O, and in one embodiment, between 10 cm H 2 O and 30 cm H 2 O. In one embodiment, a connector may be placed between the proximal portion of the pressure relief valve  26  and the distal end of the inner volumetric member  24 . The connector is suited to receive a device used to monitor expiratory pressure. 
     When the exhalation pressure exceeds the predetermined magnetic force  44 , the exhalation flow pushes the valve head  43  down and maintains such a position so as to allow the exhalation gases to pass or escape through one or more openings  45  to the ambient environment. The valve  26  remains open as long as the exhalation pressure exceeds the return force of an adjustable spring  46 . The return force of the adjustable spring  46  may be set at a force between about 0.1 cm H 2 O—up to 30 cm H 2 O, preferably between 1 cm H 2 O—up to 10 cm H 2 O, and most preferably between 1 cm H 2 O—up to 5 cm H 2 O. Typically, the valve  26  opens, or is activated, at the end of the exhalation sequence, thereby providing for synchrony between the opening and inhalation. One can vary the valve  26  opening onset by modifying the ratio between the user&#39;s normal tidal volume and the inhalation tubing  22  volume capacity, for example by adjusting a choke  47  fitted around the tubing  22  as shown in  FIGS. 1 and 2 . The choke  47  may be adjusted to accommodate users with different tidal volumes. If a user has a low tidal volume, the choke  47  will be adjusted to decrease the volume capacity of the inspiratory flow path tubing  22  in order to accommodate the lower tidal volume of the user. In another embodiment, the volume capacity of the inspiratory flow path tubing  22  may be adjusted automatically to accommodate the lower tidal volume of the user. The volume capacity of the inspiratory flow path tubing  22  should ideally be slightly lower than the tidal volume of the user to reach the necessary pressure to open the pressure relief valve  26 . If, in an exceptional case, a user&#39;s tidal volume does not exceed the inhalation tubing  22  capacity, the pressure relief valve  26  may not open, such that the volume in the inner volumetric chamber  24  is maintained. Upon the next exhalation sequence, the pressure relief valve  26  will open if the requisite pressure is reached, allowing virtually all of the exhalation gases to escape thereby decreasing the volume and pressure transmitted to the inhalation tubing  22 . The pressurized cycle will then resume with the next normal tidal volume from the user. A normal tidal volume of a user is a volume that corresponds to the volume capacity of the inspiratory flow path such that the volume of the inspiratory flow path is slightly lower than the normal tidal volume. 
     In one embodiment, the shape of the volumetric members  24 ,  25  may be flattened and hidden under a garment. During inhalation, the user may simply squeeze the outer member  25  between an arm and chest for inhalation assistance. In one embodiment, the outer volumetric member  25  is about 15 cm long×8 cm wide×4 cm thick when no pressure is being applied. In another embodiment, the inhalation tubing  22  may be placed around the abdominal area or thoracic area to enhance inhalation assistance. An enhanced assistance results from the extra pressure provided by the thorax expansion observed during inhalation attempts against obstructed airways. 
     In operation, during exhalation as shown in  FIG. 1 , the intake valves  10  are closed and all exhaust or expiratory gases are passed through the valve  20  and the flow path  23  and into the inner volumetric member  24 . When a predetermined pressure is realized by the exhaled gas in the inner volumetric member  24 , the pressure relief valve  26  opens and releases the gases to the ambient environment. The pressure relief valve  26  is configured to provide a positive expiratory pressure (PEP). As the exhalation gases enter the inner volumetric member  24 , the volume of the inner volumetric member  24  increases, or the balloon inflates, with the inner volumetric member  24  applying a pressure to the interior wall of the outer volumetric member  25 , thereby pressurizing the gases, or air, in the outer volumetric member  25 . In one preferred embodiment, the outer volumetric member  25  has a lower compliance than the inhalation tubing  22 . In one preferred embodiment, the expandable portion of the inspiratory flow path tubing  22  has a compliance of about 50 cc/cm H 2 O, the expiratory flow path tubing  23  is made of a non-compliant material, the inner volumetric member  24  has a compliance of about 75 cc/cm H 2 O, and the outer volumetric member  25  has a compliance of about 5 cc/cm H 2 O. The positive pressure in the outer volumetric member  25  during the exhalation sequence is passed on to the inspiratory flow path tubing  22 , with a one-way valve  28  positioned at the junction between the outer volumetric member  25  and the inspiratory flow path tubing  22  maintaining the collected pressure. The junction portion where the one-way valve is located is made of a non-compliant material. The one-way valve  28  allows for air to migrate from the outer volumetric member  25  to the inspiratory flow path tubing  22 , but does not allow air in the inspiratory flow path tubing to migrate back into the outer volumetric member  25  thereby maintaining the inspiratory flow path tubing in a pressurized state to assist with inhalation. In one embodiment, a plurality of one-way valves is located at the junction between the outer volumetric member  25  and the inspiratory flow path tubing  22 . 
     Referring to  FIG. 2 , during inhalation, the resiliency of the outer member  25  and the inhalation tube  22  provides a positive pressure to the air flow during the inhalation sequence through the one-way inhalation valve  21 . During the inhalation sequence, the positive pressure may drop in the outer volumetric member  25  and the inhalation tubing  22 , such that a slight negative pressure may be realized. Ambient air is then drawn in through the auxiliary valve(s)  10  located on the patient interface, and through the intake portals  27  communicating with the outer volumetric member  25 . During the inhalation sequence the inner volumetric member  24  is emptied so as to be ready for filling on the next exhalation sequence. The level of positive pressure applied to the outer volumetric member  25  and inspiratory flow path  22  by the inner volumetric member is adjusted via the control mechanism  42 . If the user talks or breathes out through their mouth while wearing a nasal mask, a temporary loss of positive pressure may result but will resume on the next nasal exhalation sequence. 
     The apparatus and method of use allow for the warmed exhalation gases to flow along the centralized expiratory flow path  23 , with the inhalation gases flowing along the inspiratory flow path  22  being warmed thereby, which may benefit users sensitive to cold air. In addition, hydrophilic material may be used for the expiratory flow paths  23 ,  24  to help humidify the inhalation gases. 
     The apparatus and method provide for several types of positive airway pressure. For example and without limitation, the pressure relief valve  26  provides for positive expiratory pressure (PEP) during the exhalation sequence, with the elasticity of the inner member  24  and the variable exhalation valve  26  preventing pressure spikes in the lungs of the user. The PEP may be used to treat snoring, obstructive sleep apnea, asthma, COPD, hypoxemia, atelectasis, CHF, bronchial congestion, high altitude sickness, and variations or combinations thereof. 
     The apparatus and method also provide positive pressure during the inhalation sequence, primarily at the beginning of the inhalation sequence. While the pressure may actually drop to a slightly negative pressure, the initial push at the commencement of the inhalation sequence is significant and helps to prevent the small airways from closing especially during the first third of the inhalation sequence. In addition, a prescribed O 2  flow may be introduced into the flow path  22 , for example from an external source  51  communicating with the flow path  22 , so as to sustain the positive pressure during inhalation while a high O 2  concentration is delivered at the crucial beginning of the inhalation sequence, thereby improving the O 2  therapy efficiency. In this way, conventional O 2  therapy may be reduced, or eliminated altogether. Other gases may be introduced into the flow path  22  from an external source  51  which is in flow communication with the flow path  22  via a connector. The same connector may also be used to connect a device for monitoring the inspiratory pressure. Another connector may be used to introduce into the flow path  22  an aerosolized substance, such as an aerosolized medicament. 
     In order to maintain a manual CPAP, the user, or a caregiver, may gently squeeze the members  24 ,  25  in sequence with the user&#39;s inhalation pace. The apparatus may also be used as a breathing exerciser for COPD and degenerative muscular disease patients to facilitate bronchial hygiene and to prevent atelectasis. In order to obtain a full CPAP, an external source of gas (air or mixed air/O 2 ) may be introduced into the flow path  22  to keep it pressurized, even at the end of the inhalation sequence. Finally, the apparatus, with the pressure relief valve  26 , may be used for manual ventilation in case of respiratory arrest. A choker  47  is used to adjust the inhalation tubing  22  to minimize the expandable portion of the inhalation tubing  22  such that the air transmitted from the outer volumetric member  25  is immediately transmitted to the patient. In another embodiment, an inflatable portion of the inspiratory pathway  22  contains pliable foam or other pliable material that maintains a residual volume of about 100 cc when no pressure is applied. The inflatable portion of the inspiratory pathway  22  is fastened between an adjustable band and the user&#39;s thorax. The band encircles the user&#39;s thorax and may be adjusted to apply pressure over the user&#39;s thorax. During inhalation, the thorax expands diametrically causing compression of the inflatable portion of inspiratory pathway  22  against the band, thereby maintaining a positive pressure inside the inflatable portion of the inspiratory pathway  22 . If a larger than normal inhalation occurs, the thorax expands further thereby maintaining pressure on the inflatable portion of the inspiratory pathway  22  while expelling residual air. During exhalation, the inflatable portion of the inspiratory pathway  22  inflates and maintains a positive pressure thereby maintaining contact with the retracting thorax. If a larger than normal exhalation occurs, the thorax will retract further providing the inflatable portion of the inspiratory pathway  22  with more room to expand and maintain contact with the user&#39;s chest thereby promoting a more complete exhalation. This embodiment allows inflation and deflation of the inflatable portion of the inspiratory pathway  22  in a manner that corresponds with the expansion and retraction of the thorax thereby automatically adjusting the user&#39;s tidal volume to the inflatable portion of the inspiratory pathway  22  air capacity as restrained by the pressure relief valve  26 . Furthermore, if in spite of using the breathing apparatus a complete obstruction occurs, such as during obstructive sleep apnea, the thorax expansion during an inhalation attempt will increase the pressure in the inspiratory pathway  22  thereby assisting to unblock the airway passage to resume normal breathing. 
     Now referring to  FIGS. 26 and 27 , a control  48  is provided underneath the expiratory valve  26  and is coupled to the spring  46 , such that the pressure of the spring  46  may be adjusted against the head valve  43 . That pressure builds the end expiratory pressure (PEEP), which is also bound to a residual volume accumulated in balloon (A). 
     In the embodiment of  FIGS. 28A-29 , the volumetric member  102  is emptied with each breathing cycle in spite of a lasting air flow resistance. To accomplish this, the volumetric member  102  is configured as resilient balloon, which collapses under a certain pressure. The minimum pressure required to keep the member  102  inflated is defined as the “closing pressure”. Once the closing pressure is exceed(ed), the member  102  will inflate much more easily, requiring less and less pressure for an increasing volume of air. This type of non-linear compliance is exemplary of the response of a latex type balloon whose membrane gets thinner and thinner as it inflates. Member  102  fully empties with each exhalation, in spite of a low pressure maintained by the expiratory valve  26  throughout the exhalation phase (PEEP). In order for member  102  to deflate completely towards the end of the patient&#39;s exhalation, a closing pressure must exceed the pressure created by the control  48  on the head valve  43  (PEEP). 
     The member  102  is inserted into a volumetric element, or housing  104  in an airtight way as shown in  FIGS. 28A-D  and  29 . In one embodiment, element  104  may be represented as a rectangular box, dimensioned for example as 3 inches×5 inches×4 inches″ (about 8 cm×13 cm×2 cm), or having a volume of about 150 cc. In other embodiments, the volume is between about 185 and 200 cc, or as much as 500 cc. The element  104  has a base  106  and top  108 , which may be similar, rigid, plastic plates  106 ,  108  connected in an airtight fashion by resilient elements  110  built into or added to a material lining. The plates  106 ,  108  are kept distant from each other by the force of the resilient elements  110 . This resilience should allow the member  104  to be hand-squeezed if needed, so to permit additional inhalation assistance. Furthermore, it will be possible, by pulling and fastening a catch mechanism, such as a knotted string or plastic element  112  or other fastener system, to fully squeeze the member  104  so as to temporarily reduce the thickness of element  104  to about ½ inch for shipping purposes or to make it more portable between uses. It will also be possible to only slightly diminish or increase the member  104  capacity by adjusting the member  104  volume via the adjustment member  112  or other fastener. This will allow the user to adjust the volume of the member  104  to the right size that is needed in order to match the selected parameters. 
     For example, with volumetric elements  102  and  114  having an initial compliance of 20 cc/cm H2O coupled to a valve  26  with an opening pressure of 5 cm H2O, the capacity of member  104  may be reduce to a less bulky 50 cc. With members  102 ,  114  coupled to a valve  26  having an opening pressure of 8 cm H2O, the capacity of member  104  may need to be increased to about 80 cc. For a valve  26  with an opening pressure of 10 cm H2O, the volume of member  104  may need to be increased about 100 cc, and so on. The expandable member  104  allows for changing the size of the device for a customized use, thereby providing for and covering the needs of a variety of pediatric, OSA, COPD patients, as well as any end users desiring further performance. 
     The variation of the opening pressure of the expiratory valve  26  and/or its PEEP allows for modulating the expiratory pattern in order to match individual needs. On the other hand, a full range of volumes and pressures for inhalation assistance can be achieved by varying the opening pressure of the valve  26  and/or the compliance of elements  102  and  114 . If desired, the compliance of element  102  can be reduced by the adjustable element  104 . For element  114 , compliance may be reduced via a plastic plate  191  as shown in  FIG. 29 , which may be secured to the top  108  of member  104 , so as to restrict the capacity of member  114 . 
     Member  104  is supplied with one or more one-way valve(s)  116  for fresh air intake, with the aperture also protected by a filter if desired. The member  114  is positioned in an airtight relationship adjacent member  104  to which it is coupled via one or more one-way valves  117 . Member  114  may be configured with the same shape, e.g., rectangular in one embodiment, that corresponds to the shape and size of member  104 . When member  114  is inflated, the thorax in the expiratory phase is retracted, minimizing the noticeable bump of the device, which may be hidden under a garment in any case. Referring to  FIG. 30 , the diameter of the tubing  118  coupled to members  102  and  114  may be reduced from 17 mm OD to 16 mm OD by utilizing a double lumen tubing, with ⅓ of the flow path  119  being used for exhalation and ⅔ of the flow path for inhalation  113 . 
     In operation, upon exhalation through the ⅓ passage way of tube  118 , and through member  102 , the internal pressure increases over its closing pressure (e.g., 6 cm H2O) and keeps increasing while member  102  inflates up to the opening pressure of valve  26  (e.g., 10 cm H2O). During that time, atmospheric air maintained within the rigid but squeezable member  104  is passed on to member  114  through a one-way valve(s)  117 . Then the valve  26  opens, and the pressure drops gradually to the PEEP level adjusted via control  48  (e.g., 4 cm H2O). During that time, member  102  deflates along with the user&#39;s exhalation through valve  26 , while member  104  is filled with fresh air admitted through the one-way valve(s)  116 . Because of the concept of communicating vessels, the initial pressure of 10 cm H2O in member  114  may tend to leak into the expiratory pathway, which ends with a PEEP of 4 cm H2O. 
     To save the built up pressure and volume contained within the inhalation pathway, a one-way valve  129  as shown in  FIGS. 31A-C  may be used. The amount of resilience of diaphragm valve  129  may vary with the elasticity of the material, surface, thickness and the layout of slits  121 . The resilience may be preset, for example by using pair of valves  129  with matching pressures. These valves  129  are made to easily connect and disconnect from the outlets  127 ,  128  of members  102  and  114  respectively. The resilience of the valve  129  may be adjustable, for example via an adjustment device such as a screw  124  that moves in front of a portion of the diaphragm  125  in order to limit, to a certain extent, the opening of the slits  121 . This system allows for an initial inhalation pressure that is higher than the PEEP, which permits a bi-level positive airway pressure or a similar BPAP mode. The split resilient diaphragm valve  129  has a defined resistance to air flow opening and another defined resistance to air flow closing. In other words, the required pressure to open the diaphragm valve  129  will be higher than the pressure to keep it open. The resistance of the valve  129  in outlet  128  may need to be tuned with the resistance of the valve  129  in the outlet  127 . For example, to synchronize the opening pressure of the inhalation valve  129  in outlet  128 , the adjustment member  124  may be adjusted to the point of self-opening of the inhalation valve  128  (without any inhalation effort) and then backed off slightly in order to find a comfortable trigger level. The valve  129  has fewer parts, is less expensive to manufacture, and may be more reliable. 
     COPD patients may become fatigued in trying to reach a peak pressure at the end of their exhalation. Indeed, the expiratory muscles&#39; strength is lowest at that point of the exhalation cycle. The full strength of the expiratory muscles is exhibited at the beginning of the exhalation, while the lungs are stretched. Passive exhalation already provides some positive pressure, which users can amplify to build a higher peak pressure while their expiratory stroke is at its maximum. It will likely require the first third of their exhalation to assist the first third of their inhalation. COPD patients will benefit the most from this energy swing between their well braced expiratory muscles and their strained inhalation muscles. In addition to the positive airways pressure effect, this expiratory saved energy represents a significant reduction of the work of breathing for a COPD patient. 
     Expiratory vibrations may also improve gas exchange. Such vibrations are possible through the diaphragm valve(s)  129  or via stretched thread(s) inserted into portion(s) of enlarged, somewhat rigid tubing suited to create beneficial vibrations transmitted to the lungs (not illustrated). 
     Referring to  FIGS. 32-35 , another valve  229  provides independent control over Peak Pressure and PEEP. The valve  229  is provided with two controls: one to adjust its opening pressure and another one to adjust its closing pressure. Therefore, this valve  229  allows for an independent control of the Peak Pressure reached within members  102 ,  104  and  114  and for an independent control of the PEEP in member  102 . 
     The valve  229  may include a rigid, plastic, rectangular frame  201 , a latex type diaphragm valve  202  disposed within the frame  201 , a magnetic strip  203 , and adjustment members, configured as screws  204 ,  205  that are used as control devices to regulate the diaphragm  202  shift. In one embodiment, the frame  201  has dimensions of about 2 cm×1.5 cm ID×2 cm depth, with an inner stop  206  located between the two ends. The stop provides three sides or surfaces, which are about 2 mm wide, and a bottom surface  207 , which is longer, e.g., about 5 mm wide. One edge of the valves  202  is fastened to the stop, with a free end of the valve disposed adjacent the larger stop surface  207 , allowing the valve to pivot or rotated about the edge thereof. 
     When the valve  202  is at rest, e.g., when no pressure is being applied, the valve will lie flat against the stop  206 , which serves as a valve seat. In order to maintain the air tightness in spite of an upstream positive pressure, a control is provided to control the amount of required pressure to move the valve  202  from the stop or seat  206 . The control may include an adjustable magnetic force. 
     In one embodiment, the magnetic force may be applied by a flexible or semi-flexible, magnetic strip  203  facing the stop surface  207 , on the same axis. For example, the magnetic strip  203  may be about 20 mm×7 mm. The strip  203  is fastened to the frame  201  at a distance of about 2 mm, proximally from the stop surface  207 . This 2 mm gap allows for an adjustment device, shown as a plastic screw shaft  209  to slide along the same axis, and between the stop surface  207  and the magnetic strip  203  as to vary the space between them. The shaft  209  is about 3 mm OD for diameter and up to 20 mm long, and may be provided with code indicators. 
     The valve  202  may be configured with metal elements in it or with a metal band  210  positioned on the proximal surface of the valve, in order to make the diaphragm  202  attractive to the magnetic strip  203 . If used, the metal band  210  may be about 20 mm by 5 mm. In order to maintain an air tight seat to the valve  229 , the attractive forces should be capable of being applied through the thickness of the stop  206 . The stop  206  may be metalized if needed. The attractive forces should be strong enough to make the flexible magnetic strip  203  bend towards the metalized valve  202  at rest unless the adjustment device, e.g., screw shaft  209  is introduced between them. The attractive forces applied to the diaphragm valve  202  determine the opening pressure or Peak Pressure which may vary from 0 to about 50 cm H2O and preferably from 3 to about 20 cm H2O. 
     Even when the adjustment device  204  is not acting on the valve  202 , it should remain fixed to the frame to avoid misplacement. The adjustment device may be provided with a grippable member  211 , or a member capable of being actuated with a tool, such as a screw driver or Allen wrench. 
     In alternative embodiments, the magnetic force may be varied via an optional electric module (battery operated). This module may, for example, automatically increase the Opening Pressure if the valve  229  does not open for determined laps of time following repeated obstructive apneas. 
     The closing pressure may be adjusted via adjustment device  205  located downstream of the diaphragm valve  202 , e.g., about 2 mm, as shown in  FIGS. 35 and 37 . In one embodiment, the adjustment device  205  includes a screw shaft  212 , e.g., about 3 mm OD diameter and 10 mm long, projecting inwardly into the flow path defined by the frame  201 . When the valve  229  opens, the valve  202  engages the shaft  212 , which impedes the bending and flexing of the valve. The portion of the diaphragm  202  that is engaged by the adjustable shaft  212  length will vary the recall memory of the diaphragm  202  and consequently the Closing Pressure or PEEP. The adjustment device, e.g., the screw  212  may be provided with code indicators. The corners of the valve  202  not supported by the shaft  212  will bend more freely in presence of high pressure, therefore dynamically preventing bursts of pressure. 
     The valve  229  provides for different users to choose the fraction of their expiration that will be used to assist the subsequent inhalation. Therefore, one can choose to use the first third, the first half, or the almost totality of their expiration to assist inhalation. In addition, regulation of PEEP is performed independent of the Peak Pressure and can be adjusted as needed. When positioned at the member  114  outlet  128 , the Peak Pressure control allows for precisely choosing the requested inhalation effort to trigger the valve&#39;s  229  opening, while the positive airways pressure is still sustained. For its part, the closing pressure control allows the user to modulate the inhalation flow assistance. Indeed, the user can choose how the volume of inhalation assistance is delivered; either with a burst of air at the beginning of the inhalation, extended during a fraction of, or during the entire inhalation. 
     The present embodiment of  FIGS. 36A  and B allows permissive hypercapnia as there is no one-way valve between member  301  and the patient interface. Member  301  may have a more linear compliance such as the one found with typical black anesthesia bags. The expiratory member  301  emptying will in fact be completed by the user. Doing so will permit some CO2 re-breathing. There are some physiological effects of permissive hypercapnia. For example, it shifts the oxyhemoglobin dissociation curve to the right thereby providing better O2 release at the tissue level. In addition, it provides a bronchodilator, which eases work of breathing, and a vasodilator, which improves cardiac output. In addition, minute ventilation may increase, which tends to lessen hypopnea. It may also provide an anti-inflammatory agent. All those physiological effects are beneficial for patients who are suffering from a respiratory ailment, such as COPD, or those who want to enhance their aerobic capacity. 
     Referring to  FIGS. 43-46 , the adjustment members  204 ,  205  may be replaced by a single adjustment member  1204  positioned further from the valve  202 , e.g., 5-6 mm, rather than 2 mm, such that the control member  1204  does not contract the valve  202  when in the open position, as shown in  FIGS. 43 and 45 . The diameter of the adjustment member  1204  may be larger, e.g., 7 mm, instead of the suggested 3 mm for the screw shaft  212 . The larger diameter allows the adjustment member  1204  to partially obstruct the inhalation tube, which is about 10 mm in one embodiment. The further the adjustment member  1204  is screwed, or otherwise extended, into the inhalation pathway, the more the adjustment member  1204  reduced the orifice through which the pressurized volume of air travels. Consequently, the user may adjust the flow of inhaled air without a broad range so as to better assist the inhalation. Indeed, the flow may be adjusted from a burst of air at the beginning of the inhalation to light flow, based on the choice and need of the user. The adjustable, restricting airflow adjustment member  1204 , or valve, may be positioned at the outlet to create a variable back pressure upon exhalation. For a given size orifice, the expiratory flow rate will influence the amount of back pressure and so the positive pressure built in the member  102  fills the element  114  with pressurized volume of fresh air. Therefore, by changing their expiratory flow rate, the user may gain an additional control of their peak pressure and inhalation control. The expiratory flow rate automatically follows the user&#39;s level of activity, with the higher the volume minute, the higher the positive pressure. If the pressure in element  102  drops under a desired level of PEEP at the end of a prolonged exhalation, the stored pressurized volume in element  114  will be released, providing a signal to the user to inhale. Because the user draws in pressurized air from element  114 , the air from element  114  will flow to the user&#39;s airways, rather than escaping through the outlet of element  102  located further away and having an airflow restriction. The user may also temporarily and/or partially block the outlet of element  102  with a finger to increase the Peak pressure, independently of the expiratory airflow to increase the inhalation assistance. 
     Referring to  FIGS. 39-42C , different mechanism embodiments are provided to assist in the emptying of the various volumetric elements, including for example and without limitation element  102 ,  301 , between exhalations. Referring to  FIG. 39 , in a first embodiment, the element  102 ,  301  may be made of a balloon or bellows with a non-linear compliance. The compliance may correspond for example for the first 50 cc of exhalation to a raise in pressure from 0 to 8 cm H 2 O (or 1 cm H 2 O over the PEEP), with the balloon releasing and the compliance raises to about 100 cc/cm H 2 O or more. 
     Referring to  FIGS. 40A  and B, an adjustable mechanism can be actuated by a portion, e.g., top, of the element  102 ,  301  raising with exhalation. 
     When a maximum pressure is reached, valve  127  opens and the element  102  starts to deflate. In response, a rigid top  1001  presses down on a lower arm  1003 , rotating the arm. Stored energy in the mechanism is released and an upper arm  1005  presses down on the element  102  to complete the emptying thereof. 
     In the embodiment shown in  FIGS. 41 and 47-54B , a three way valve initially allows expiratory air flow through opening  1111  to inflate the element  102 . Once the maximum pressure is reached, the valve  127  opens and the expiratory air flow is redirected to a restrictive outlet  1109  to create a PEEP. At the same time, a second larger outlet  1113  is opened allow a quick, free emptying of element  102 . The outlet  1113  facilitates the emptying of the element  102 . 
     Outlet  1109  is a high resistance port that connects the patient&#39;s expiratory flow to atmosphere, and outlet  1113  is a low resistance port that connects the exhalation membrane to atmosphere. At the beginning of exhalation, outlets  1109  and  1113  are closed, and outlet  1111  is opened, resulting in all expiratory flow being directed into the exhalation membrane and charging the system. Once a peak pressure is reached, the outlet  1111  is closed, and outlets  1109  and  1113  are opened, thereby diverting all of the remaining expiratory flow from the patient to atmosphere through outlet  1109 , with the high resistance maintaining PEP and also allowing the exhalation membrane to deflate completely through the low resistance outlet  1113 . Outlet  1109  closes at the desired PEEP level, similar to other exhalation valves disclosed herein. 
     Maintaining residual volume in the inhalation membrane after each assist greatly improves the efficiency of the system, because opening and closing the membrane wastes energy, and may shorten the life span of the membrane. Inflation and deflation of an elastic membrane follow different paths on the pressure-volume curve due to hysteresis and as a result, the closing pressure of the membrane is slightly lower than its opening pressure. Using a pressure sensor, electronic solenoid valve and control system, the inhalation port is opened when PEEP is reached to commence inhalation. As the pressure in the inhalation membrane rises, since the membrane is decreasing in volume as the patient inhales, the pressure is continuously monitored and when a threshold just below the membranes closing pressure is reached, the inhalation port is closed. This maintains the membrane at a volume above its closing volume. 
     Initially, and referring to  FIGS. 47 and 48 , the inhalation membrane  3000  is primed through a priming port  3004  to get the membrane above its opening volume. This priming is currently performed with a hand pump. The system is then turned on. Referring to  FIG. 49 , valve  3008  is the only valve in the open position, allowing the user&#39;s exhaled breath to flow from the interface  3002  through port  1111  and into the exhalation membrane  3014 , causing it to expand. Referring to  FIG. 50 , as the exhalation membrane  3014  expands inside the exhalation chamber, the membrane  3014  drives the surrounding atmospheric air through a check valve  3016  and into the inhalation membrane  3000 , causing the membrane  3000  to expand. Referring to  FIG. 51 , when the exhalation membrane  3014  expands to a certain pressure as sensed by pressure port  3018 , valve  3008  closes and valves  3010  and  3012  open. Valve  3012  allows the air inside the exhalation membrane  3014  to escape out to atmosphere through outlet  1113 . Valve  3010  allows the user to finish his/her exhalation through a high resistance port  1109  (continuing PEP therapy). As the exhalation membrane  3014  deflates, it draws fresh atmospheric air into the exhalation chamber through a separate check valve  3020 . Referring to  FIGS. 52 and 53 , the user can continue to exhale even if the exhalation membrane  3014  is already emptied. Once the user&#39;s airway pressure drops to a desired PEEP value (positive end expiratory pressure) as determined by pressure port  3018 , valves  3010 ,  3012  close and the inhalation valve  3024  opens. The inhalation valve  3024  is the only valve open and connects the user to the inhalation membrane  3000  through the interface  3002 . Pressurized air is driven into the user&#39;s airways until the inhalation membrane  3000  reaches its closing pressure as determined by pressure port  3006 . At this point, the inhalation valve  3024  closes to prevent membrane  3000  collapse as shown in  FIG. 54A .  FIGS. 54A  and B show internal and external views, with the inhalation valve  3024  closing at the inhalation membrane&#39;s closing pressure to prevent complete membrane closure. The remainder of the user&#39;s inhalation is at atmospheric pressure through a check valve  3026  as shown in  FIG. 54 b   . Pressure ports  3006 ,  3018  feed readings to a control circuit which also drives the solenoids. Opening and closing pressures can be adjusted by changing the variable values in the software. In addition, an exhalation resistance adjustment screw and a volume adjustment plate/screw may be provided to allow the user to adjust how much resistance they feel when they are exhaling through port  1109 . The volume adjustment plate/screw allows the user to adjust the device so that it is tuned to their own exhaled volume. 
     Referring to  FIGS. 42A-C , an adjustable magnet  1135  is positioned underneath the element  102 , which is provided with a metalized top  1131  and a “V” shape in cross-section. The top  1131  raises with the expiratory air flow, with the attractive force of the magnet  1135  decreasing and thus reducing the required pressure to inflate the element  102 . The pressure curve matches the natural pressure curve of normal or forced exhalations. After the opening of the valve  127 , the metalized top  1131  of the element  102  drops and the attractive force increases to squeeze the top against the base  1133 , forcing the residual air to expel. Alternatively, an electro-magnetic force may be applied intermittently. In one embodiment, the attractive force may be applied only when the valve  127  is opened, thereby optimizing the efficiency of the system as no opening resistance would be opposed to the user&#39;s exhalation force, preserving this energy to inflate the inhalation reservoir  114 . The mechanism of  FIGS. 42A-C  may be used in combination with the systems of  FIGS. 39-41 . 
     The following scenario provides an example of the interaction between the breathing assistance device with permissive hypercapnia and a user. In one exemplary embodiment, a hypothetical adult male has an anatomical dead space of 150 cc. 
     The following scenario has these parameters: Peak expiratory pressure: 20 cm H2O, PEEP: 5 cm H2O, and member  301  and  302  compliance: 30 cc/cm H2O. 
     Tidal volume 400 cc 
     First exhalation: 400 cc. 
     The first exhaled 300 cc will inflate members  301 ,  302  to a volume of 300 cc. Member  301  will be at a pressure of 20 cm H2O and member  302  will be at a pressure of 10 cmH2O. 
     Valve  303  opens and patient exhales through its last 100 cc with member  301  emptying. 
     Member  301  will empty down to the PEEP level of 5 cm H2O which corresponds to a residual volume of 150 cc. 
     First inhalation: 400 cc. 
     Patient starts to breathe in 15 cc of mixed air through the expiratory  304  and inspiratory  305  limbs, both pressurized to 5 cm H2O. As soon as the pressure drops to 4.5 cm H2O, valve  306 , pre-adjusted to an opening pressure of 5 cm H2O opens to assist inhalation with fresh air pressurized to 10 cm H2O. 
     When the pressure reaches 4.5 cm H2O in member  302 , 157.5 cc of fresh air and 7.5 cc of re-breathed air will have been provided to patient followed with 235 cc of mixed re-breathed air and fresh air coming from members  301 ,  302 . Inhalation and exhalation membranes will have residual volumes of 17.5 cc each at the end of inhalation of 400 cc. The process repeats itself. 
     For recurrent CO2 inhalation, one has to choose a high ratio PEEP Peak Pressure to increase the inhaled CO2, e.g., 8/10 while a low ratio PEEP Peak pressure will lower CO2 inhalation, e.g., 4/10. Another means to vary the inhaled CO2 will be in choosing an asymmetrical compliance for members  301 ,  302 , e.g., a ratio of 30 cc/cmH2O for member  301  versus a compliance of 15 cc/cmH2O for member  302 , which will cause higher inhaled CO2 than a ratio of 15 cc/cmH2O for both members  301 ,  302 . These variables give full control on the amount of permissive inhaled CO2. 
     Referring to  FIGS. 37 and 38 , the valve  229  previously discussed may be provided with a magnetic strip  333  coupled to an electromagnetic generator  334  instead of the regular magnetic strip  203  controlled with the adjustment device  209 . A battery  335  or AC operated electromagnetic generator  334  is coupled to magnetic strips  333 , a motion sensor  336 , a chronometer  337  and a meter  338  (to monitor valve  229  openings pattern). When the number of openings/min falls under a pre-set rate, a command is sent to the generator  334  to increase the electromagnetic forces evenly applied to the magnetic bands  333  on valve  303  and valve  306 , or other valves  229 , so to gradually increase the required force to open these valves and therefore, the airways pressures. 
     On the other hand, when a stable breathing pattern is recognized through monitoring, a command is sent to the generator  334  to decrease the electromagnetic forces applied to the magnetic bands  333  so to gradually decrease the airways pressures. This electronic module  339  allows gradual increasing or decreasing positive airways pressures in order to meet the ever changing user&#39;s needs throughout a single night. For instance, a patient may benefit from very low pressures while falling asleep, which provides the advantages of a ramp and later on be confronted with much higher pressures, as OSA come up while deeply sleeping. 
     Referring to  FIGS. 38A  and B, one embodiment of a breathing assistance device provides a means to get over obstructed airways during potential episodes of obstructive sleep apnea. A compressor  349 , used with the optional meter  338 , directs the users to find the best parameters for any individual who wants to prevent OSA with the least amount of pressure. The compressor mechanism  349  includes: an electrical source  335 , a small motor  341 , a strap  342 , a dome  343 , a motion sensor  336 , a chronometer  337  and an events meter  338 . 
     After a pre-determined length of time without detecting patient&#39;s breathing, the compressor  349  squeezes the members  302 ,  347 ,  301  to generate a positive upper airways pressure to unblock the air passage and thus to allow some ventilation that help to maintain a decent blood oxygenation. Moreover, that little drive may be all a patient needs to change its breathing pattern and to resume a regular breathing with the breathing assistance device. 
     In operation, the motion sensor monitors the valve  303  openings. After a pre-determined number of seconds without valve  303  moving, a signal is sent to the small motor  341  that starts to turn its shaft  344 , around which a strap  342  is wound into a bobbin  345 . The strap  342  passes through guides  346  encircling the members  301 ,  302  and is fastened to a light plastic dome  343  covering  302 . When the strap  342  pulls down on the dome  343 , it squeezes Elements  302 ,  347  and  301 , evacuating the volume of air contained in the breathing apparatus towards patient&#39;s airways as shown in  FIG. 38B . The maximum pressure applied to the airways will be limited by the opening pressure of valve  303 . An optional electromagnetic system  339  may be used with the valve  229  to gradually increase airways pressures as the patient falls asleep or if OSA resume. As soon as the valve  303  opens, a signal is sent to the small motor  341  that stops running. The shaft  344  then falls on neutral and the strap  342  starts to unroll, due to the member  347  memory recall and inflation of the member  302 . The compressor  349  also may be supplied with AC current or via a 9 volt battery  335  for example. The breathing assistance device and compressor  349  may lie on a bedside table or be worn on patient&#39;s chest. 
     The optional events meter  338  is in line with the motion sensor  336  signal, and will count the number of times the motor  341  starts to run hence the number of events during a period of time. The meter  338  is resettable to 0. This information can be very useful to determine the most advantageous parameters setting (if the electromagnetic valve  229  is not used). 
     The compressor  349  provides many advantages over the existing CPAP machines, including no continuous airflow that dries up mucosa, no need for an expensive humidifier, decreased daily maintenance, very portable and autonomous, quiet operation, lower purchasing cost, and lower operational cost. 
     Referring to  FIGS. 5A-F ,  7  and  21 , another embodiment of a breathing assistance apparatus includes a housing  400  having an exhalation chamber  402  and an inhalation chamber  404 . The exhalation chamber is divided into two variable volume chambers  406 ,  408  sealingly separated by a displaceable piston  410 , biased by a spring  412 , and a rolling diaphragm  414  sealing the two variable chambers  406 ,  408  one from the other. The piston and diaphragm may be integrally or separately formed. The first variable chamber  406  holds an exhaust gas, while the other variable chamber  408  is connected to the inhalation chamber  404 . Both variable chambers  406 ,  408  include inlet and outlet ports  416 ,  418 ,  420 ,  422 . The inlet and outlet ports  420 ,  422  on the second variable chamber  408  are configured with one-way valves  424 ,  426 . The spring  412  biases the piston  410  and valve  414  upwardly to minimize the volume of the first variable chamber  406 . 
     The inhalation chamber  404  also includes a piston  428  and rolling diaphragm  430  separating two variable volume chambers  432 ,  434 . Only the upper chamber  432  however, includes an inlet and outlet port  438 ,  440 . A spring  436  biases the piston  428  and diaphragm  430  upwardly to minimize the volume of the upper, variable inhalation chamber  432 . Again, the piston and diaphragm may be integrally or separately formed. 
     In operation, the user exhales, with the exhaled breath passing through the inlet port  416  of the exhaust gas chamber  402  and pushing the diaphragm  414  and piston  410  against the force of the spring  412  downwardly to descend in the exhalation chamber  402 . This movement increases the pressure in the second variable chamber  408 . The pressure opens the one-way valve  424 , with air traveling through a conduit to the inhalation chamber  404  through the inlet port  438 . The increased pressure in the inhalation chamber  404  pushes the piston  428  downwardly therein against the force of the spring  436 , and thereby increases the pressure in the inhalation chamber  404 , including the variable upper chamber  432 . 
     Upon pressurization of the inhalation chamber  404 ,  432 , a valve  450  (described in detail below) opens in the outlet port  418  and allows the user&#39;s exhaled breath to escape the upper variable exhalation chamber  406 . As the pressure on the upper side of the piston  410  drops, the spring  412  returns the piston  410  to its normal, at-rest position. At the same time, the pressure on the back-side of the piston  410  drops, with the inlet valve  426  opening to allow fresh atmospheric air into the lower variable chamber  408  to equalize the pressure. The exhalation valve  450  has a closing pressure that is lower than its opening pressure in order to independently control PEEP. At the end of exhalation, the patient inhales from the inhalation chamber  404 ,  432  via a mouthpiece  500 , described below, having a one-way valve  502  to receive the stored inhalation assist, or pressurized air in the inhalation chamber. A second one-way valve  504  in the mouthpiece prevents the user from rebreathing their own exhaled breath. The entire process is repeated with each breath. 
     Referring to  FIG. 6 , an alternative embodiment of a breathing assistance apparatus is shown, but with the rolling diaphragm/valves arranged serially in chambers  602 ,  604  order to reduce the size of the device. The device operates in the same way as the embodiment of  FIGS. 5A-F . 
     Referring to  FIGS. 8A-10C and 24 , an alternative embodiment of a breathing apparatus is shown as including a housing  700  with a pair of handles  760  disposed on opposite sides thereof. The housing has a clam-shell shape, and upper and lower components  702 ,  704  that are coupled together to form an interior cavity, which holds an exhalation and inhalation chamber  402 ,  404  and the coupling therebetween. 
     In one embodiment, the exhalation and inhalation chambers  402 ,  404  are each divided by elastic membranes  620 ,  622  rather than by pistons and springs. A first elastic membrane  620  is located inside an exhalation chamber, such that during inflation the membrane forces air into the inhalation chamber as explained above with respect to the spring and piston embodiment. The membrane  622 , surrounded by air at atmospheric pressure, and alternatively the piston  410  and spring  412 , are referred to as biasing members. One-way valves  424 ,  426  are arranged in the inlet and outlet ports as described above. The average exhalation chamber membrane  620  compliance, 100-150 cc/cmH2O, is relatively large compared to the inhalation chamber membrane  622 , while having enough resilience to deflate completely within 1-2 seconds. For example, in one embodiment, an anesthesia bag may serve as the exhalation membrane  620 . 
     The volume output of the device is dependent on several variables, including tidal volume, exhalation chamber and membrane volumes, inhalation chamber volume, inhalation and/or exhalation membrane compliance, number of exhalations before obtaining an inhalation assist, peak PEP setting, PEEP and dead space. Many of these variables may be adjustable. For example, as shown in  FIGS. 10A-C , the exhalation chamber  630  may have a variable volume, and may be configured in one embodiment as an adjustable bellow. The exhalation membrane  620  is located inside the variable volume exhalation chamber  630 , which is adjustable via a screw mechanism. A smaller volume exhalation chamber, e.g., a compressed bellow shown in  FIG. 10A , would be more appropriate for users with lower tidal volumes, while a larger volume exhalation chamber, e.g., an expanded bellow shown in  FIG. 10C , would be more appropriate for users with higher tidal volumes. The inhalation chamber membrane  622  may also be located in a variable volume housing, such as a bellow, which allows free expansion of the inhalation chamber, but which would allow the user to compress the bellow and thereby provided additional IPAP during inhalation. 
     The use of an elastic membrane  622  may provide certain advantages as shown in the graph at  FIG. 11 . Once opened, as the inhalation membrane  622  continues to expand, the internal pressure at any given time will decrease up to a certain volume. This means that for a user obtaining in inhalation assist from an elastic membrane, the pressure will remain at a near constant lever  1  during deflation for most of the volume delivered, whereas in the spring and piston embodiment of  FIGS. 5A-F , the pressure will drop off linearly with volume. In this way, the elastic membrane provides a plateau-like pressure behavior. 
     The minimum peak pressure required to operate the elastic membrane embodiment is about 25 cmH 2 O. Peak pressures lower than this amount may result in the membrane not opening. The exhalation membrane  620  with maximum compliance is desirable, such that minimal energy is expended in inflating the membrane, and will further reduce the peak pressure required to operate the device. Alternatively, a piston  632  of relatively large area may be exposed to the exhalation pressure and be coupled by way of a rod  636  or other link to a smaller piston  634  that pressurizes the inhalation chamber  402 ,  622  as shown in  FIG. 25 . 
     When using a high compliance exhalation membrane  622 , a valve system may be necessary to ensure that the membrane deflates completely prior to subsequent exhalations. 
     Referring to  FIGS. 12A-C , the mouthpiece  500  is shown as including a patient interface port  510 , configured in one embodiment as a tube that is received in the user&#39;s mouth. The mouthpiece includes three flow paths  512 ,  514 ,  516  communicating with the interface port, with one-way valves  504 ,  502 ,  506  disposed in each flow path. A first flow path  512  communicates with the exhalation chamber inlet port  416  and a second flow path  514  communicates with the inhalation chamber outlet port  440 . The third port  516  communicates with the atmosphere, such that the user may inhale freely through a one-way valve  506  once the inhalation chamber  404 ,  622  has emptied during the first third of inhalation. In an alternative embodiment of the mouthpiece, shown in  FIG. 13 , an additional user activated valve  520 , such as a bite-valve, communicates with the inhalation port  514 . In this way, the user may control when they want an inhalation assist, which is provided only when the valve  520  is activated by the user independent of their breathing. This may allow for a build-up of larger volume inhalation assists over the course of multiple exhalations. Alternatively, the interface  510  may be configured as a mask or a nasal insert. 
     Referring to  FIGS. 14A  and B and  23 , a peak pressure and peep valve  450  is shown. The valve opens at a set pressure, and re-seals or closes at a different, lower pressure. The opening and closing pressures are controlled and adjusted independently relative to each other. The valve  450  includes a piston housing  452  and spring adjuster member  454  threadably engaged with the piston housing. A piston  456  is disposed in the housing, and includes a sealing cone  458  at the bottom thereof. A spring guide  460  extends longitudinally within the housing, and a spring  462  is disposed between the adjuster member  454  and the piston  456 . An adjuster housing  464  is coupled to the bottom of the piston housing, and includes a port  466  communicating with an interior thereof, and the bottom of the piston housing. In one embodiment, the sealing cone  458  is configured with a coupling member  468 , such as a magnet. A peak pressure adjuster  472 , configured with a rod with a second magnet  470 , is threadably coupled to the adjuster housing  464 . The adjuster  472  may be rotated such that the second magnet  470  is closer or further away from the sealing cone magnet  468 , thereby applying a greater or lesser coupling force therebetween. 
     In a closed state, shown in  FIG. 14A , pressure is allowed to build up on a upstream side of the sealing cone  458 , made of silicone so as to minimize leakage. Once sufficient pressure is created from the exhalation chamber communicated through port  466  from outlet port  418 , the coupling force of the magnets  468 ,  470  is overcome such the sealing cone  458  is moved away from its valve seat  474 , thereby allowing the pressure to be applied to the piston  456 . The opening pressure may be adjusted and controlled by varying the distance between the magnets  468 ,  470 . As the pressure forces the piston  456  upward, the attractive force of the magnet drops off rapidly, and becomes negligible. At the same time, the spring  462  is compressed and provides resistance to the upward movement of the piston  456 . The pressure is relieved by flow between the walls of the piston and the piston housing. Once the pressure drops below a certain threshold, the spring  462  pushes the piston  456  downwardly until the magnetic attractive force draws the sealing cone  458  closed against the valve seat  474 . The closing pressure may be adjusted by adjusting the biasing force of the spring  462  by varying the position of the spring adjuster  454 . In this way, the spring adjuster  454  is used to set the PEEP. 
     Referring to  FIGS. 15A-16B and 20 , an alternative peak pressure and peep valve  800  is shown. The valve opens at a set pressure, and re-seals or closes at a different, lower pressure. The opening and closing pressures are controlled and adjusted independently relative to each other. The valve includes a PEEP adjustment housing  802 , a peak pressure housing  804 , a PEEP adjuster  806  and a peak pressure adjuster  808 . A PEEP piston  810  is disposed in the housing  802 , with a spring  812  disposed between the piston  810  and adjuster  806 . A popping diaphragm  814  is disposed adjacent the piston. A peak pressure piston  816  is disposed in the peak pressure housing. An adjustable coupling mechanism, configured as a pair of magnets  818 ,  820 , is connected to the popping diaphragm  814 . 
     In a closed state, pressure is allowed to build on one side of the popping diaphragm  814 . At a threshold pressure, the diaphragm  814  inverts due to an over-center geometry, pulling up a pressure release piston  816  having a gate  822 . The gate  822  opens an exhalation passageway  824 . The pressure required to open the gate may be adjusted, for example by varying the distance between the magnets  818 ,  820 . The large travel experienced by the diaphragm  814  during the inversion process makes the attractive force negligible. The diaphragm  814  is stable in the inverted position due to the back pressure as it moves against the PEEP piston  810 . The spring force exerted by the spring  812  against the PEEP piston  810  may be adjusted by adjusting the distance between the adjuster  806  and the piston  810 . In this way, the pressure at which the diaphragm  814  will return to its initial state and close the gate  822  may be varied. In an alternative embodiment, shown in  FIGS. 17A  and B, slits  828  may be provided in the sides of the diaphragm  830  such that when the diaphragm is in an initial, non-inverted state, an airtight seal is created, but once inverted, air is able to pass through the slits  828  with some resistance, which would eliminate the need for the gate mechanism. 
     In another embodiment, shown in  FIGS. 18A-19B and 22 , an alternative peak pressure and peep valve  860  is shown. The valve  860  opens at a set pressure, and re-seals or closes at a different, lower pressure. The valve includes a spring housing  862 , a spring adjuster  864 , a spring  866 , a spring retainer cap  868 , a needle housing  870 , a rolling diaphragm  872 , a piston  874  with a sealing needle  876  and an isolating membrane  878 . In a closed state, a small area of the rolling diaphragm  872  is exposed to pressurized exhaust air. A spring  866  applies a compression force to balance the pressurized force on the diaphragm  872 . The spring force may be adjusted by a spring adjuster  864 . Once an opening pressure is reached, the rolling diaphragm  872  translates upward, lifting off a sealing seat  880  and moving the sealing needle  876  from its seat  882 . The lifting of the sealing needle  876  allows the pressurized air to escape from exposed outlet ports  884 . At the same time, the rolling diaphragm  872  exposes more of its surface area to the pressurized air once opened, such that a lower pressure is required to keep the diaphragm  872  in an opened position. The ratio of the exposed areas in the closed and open position is as follows:
 
 P   closed   A   closed   =P   open   A   open  
 
 P   closed =Peak Pressure
 
 P   open =PEEP
 
PEEP/Peak Pressure= A   closed   /A   open  
 
     The adjustment spring  866  affects both pressures simultaneously, and in this embodiment, peak pressure and PEEP are not independently adjustable. 
     Balloons and other elastic membranes typically expand in a highly non-linear fashion. Upon reaching a peak pressure, referred to herein as the opening pressure, the elastic membrane readily expands. As the elastic membrane expands, the elastic membrane&#39;s walls thin out as they are stretched, making it easier to expand the elastic membrane further until the elastic membrane is stretched or otherwise expanded to its limit. At this point, pressure begins to build and risk of rupture increases. This is known as the valley pressure point or local minimum pressure point. The average pressure between the opening pressure and the pressure at the local minimum pressure point is referred to herein as the plateau pressure. 
     In one or more of the embodiments disclosed herein, the opening pressure for the inhalation membrane may be between 5 cmH2O-20 cmH2O, or preferably between 10 cmH2O-20 cmH2O, or most preferably between 12 cmH2O-15 cmH2O, and the plateau pressure for the inhalation membrane may be between 1 cm2O-20 cmH2O, or preferably between 8 cmH2O-20 cmH2O, or most preferably between 8 cmH2O-12 cmH2O. 
     In one or more of the embodiments disclosed herein, the opening pressure for the exhalation membrane may be between 0.1 cmH2O-15 cmH2O, or preferably between 0.1 cmH2O-10 cmH2O, or most preferably between 0.1 cmH2O up to 5 cmH2O, and the plateau pressure for the exhalation membrane may be between 0.1 cmH2O and 10 cmH2O, or preferably between 0.1 cmH2O and 5 cmH2O or most preferably between 0.1 cmH2O and 2 cmH2O. The highest possible compliance is desired for the exhalation membrane as long as it has enough elasticity to deflate to its initial volume in a matter of a few seconds through a low resistance port. 
     In one or more of the embodiments disclosed herein, the volume for each of the inhalation membrane and the exhalation membrane at its local minimum pressure point may be between 300 cc-1000 cc, or preferably between 500 cc-1000 cc or most preferably between 500 cc-700 cc. 
     In one or more of the embodiments disclosed herein, the inhalation chamber comprises a biasing member such as a constant force spring to maintain the inhalation chamber at a constant pressure throughout the delivered volume. 
     The desired magnitude of the force of the constant force spring may be derived based on the product of the piston/rolling diaphragm cross-sectional area and the desired inspiratory positive airway pressure (IPAP)−F spring =A piston P IPAP . In one or more of the embodiments, the inhalation chamber comprises a constant force spring having a force large enough to provide IPAP of 5 cmH2O to 20 cmH2O, or preferably between 8 cmH2O and 20 cmH2O, or most preferably between 8 cmH2O and 12 cmH2O. 
     In one or more of the embodiments disclosed herein, the exhalation membrane comprises a biasing member such as a constant force spring with just enough biasing force to return the piston/rolling diaphragm to its initial position at a pressure difference of the desired PEEP. In some embodiments, the force may be adjusted. 
     Another embodiment of the breathing apparatus comprises an exhalation member that is expandable and contractible, wherein said exhalation member comprises an inlet port adapted for fluid communication with a user interface and an outlet port; and an inhalation member that is expandable and contractible comprising an inlet port in fluid communication with said exhalation member and an outlet port in fluid communication with said user interface; wherein said exhalation member is expandable from a first volume to a second volume in response to an exhaust flow; and wherein said inhalation member is expandable from a first volume to a second volume in response to a pressurized flow from said exhalation member to said inlet port of said inhalation member. The exhalation member or the inhalation member or both may comprise an elastic material. The exhalation member or the inhalation member or both may comprise(s) a biasing member. 
     Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. As such, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is the appended claims, including all equivalents thereof, which are intended to define the scope of the invention.