Apparatus for maintaining airway patency

SPECIFIC REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation application which claims priority to and incorporates by reference application Ser. No. 09/550,986 filed Apr. 17, 2000.

BACKGROUND OF THE INVENTION

[0002] Obstructive sleep apnea is a common disorder that involves tissue occlusion of the nasopharyngeal airway during sleep which impedes a patient's normal breathing cycle. Multiple sequential apnea episodes may result in severe sleep disruption of which the patient may not even be aware. Moreover, swollen tissue in the airway often results in excessive heavy snoring. Extreme sleep apnea is a serious disease which may affect as much as three percent of the adult population, and heavy snoring is much more common, particularly with overweight individuals.

[0003] Surgical intervention is always an option in alleviating obstructive sleep apnea or heavy snoring, however, most patients prefer to address the problem with non-invasive treatment. One treatment program involves the use of continuous positive airway pressure delivered to the patient's airway to maintain the airway in a continuously open state during sleep. The equipment required to deliver continuous positive airway pressure to the airway of a patient includes a fan or blower for generating a pressurized flow through a hose coupled to a mask or nasal device which the patient places over his or her nose and uses straps about the head to fasten the device in place.

[0004] Many patients cannot tolerate the application of continuous positive airway pressure, particularly because of the discomfort associated with exhalation against a continuous positive pressure. An attempt has been made to alleviate this problem by the provision of a method and apparatus which provides a substantially constant elevated airway pressure to the patient's airway, with periodic short term reductions of the elevated airway pressure to a pressure of lesser magnitude. A further advance in such treatment involves the application of alternative high- and low-level positive airway pressure wherein the low-level pressure coincides with the breath exhalation of the patient's breathing cycle.

[0005] A method and apparatus for the application of continuous positive airway pressure to a patient's airway is disclosed in U.S. Pat. No. 4,655,213, issued to Rapoport et al. The concept of providing a substantially constant elevated airway pressure with periodic short-term pressure reductions is disclosed in U.S. Pat. No. 4,773,441, issued to John B. Downs. A bi-level system of applying alternating high- and low-level positive airway pressure to a patient's airway is disclosed in U.S. Pat. No. 5,148,802, issued to Sanders et al.

[0006] The methods and apparatus disclosed in the prior art for treating patients afflicted with such maladies as sleep apnea and snoring present a number of problems which need to be addressed. The equipment utilized in such treatment is far too bulky and cumbersome. The air stream delivered to the patient tends to dehydrate the nasopharyngeal tissue. The unnatural sensation and discomfort experienced by the patient in overcoming the positive pressure during breath exhalation results in many patients abandoning the use of a system that is in all other respects quite beneficial.

SUMMARY OF THE INVENTION

[0007] The present invention comprehends the treatment of such disorders as obstructive sleep apnea or heavy snoring by providing an apparatus capable of delivering a pressurized burst or pulse of air to a patient's nasopharyngeal airway at the moment of termination of the patient's breath exhalation during the breathing cycle. The pulse of pressurized airflow is sufficient to prevent the development of airway tissue occlusion and maintain the airway open for normal breathing.

[0008] Hence, it is a primary objective of the present invention to provide a method of alleviating sleep apnea or snoring by delivering ambient air to a patient's airway in the form of an air bolus, wherein the patient's exhaled air is utilized to actuate an energy storing means to cause delivery of the air bolus into the airway.

[0009] Still another objective of the present invention is to provide an apparatus capable of providing a pressurized pulse of air through a nasal device and into the nasopharyngeal airway of a sleeping patient, wherein the pressurized airflow is triggered by the breath exhalation of the patient and will continue sequentially with each exhaled breath.

[0010] It is also an objective of the present invention to provide an apparatus as heretofore described which preferably includes a nasal device for attachment to a patient's nose, and a housing with a chamber capable of storing a fresh air supply for release to the nasal device and into the patient's airway to thus promote a normal breathing cycle.

[0011] It is also an objective of the present invention to provide an apparatus as heretofore described which is self-contained as a unitized structure that obviates the need for auxiliary remote bedside equipment requiring a large fan or compressor.

[0012] Practice of the method of this invention comprises the steps of providing a primary airflow conduit for delivering ambient air into the patient's airway and providing a bolus chamber in airflow connection with the airflow conduit which is capable of delivering a bolus of ambient air. Energy storing means responsive to the patient's breath exhalation is utilized to force the bolus of air from the chamber and through the conduit and into the patient's airway. The patient's exhaled air is used to actuate or trigger the energy storing means and cause, by the release of its energy, the delivery of the bolus of air to the patient's airway.

[0013] The invention also provides an apparatus in the form of a unitary structure, such as a containment housing, with the housing being coupled to a nasal device. The nasal device may be a mask sealed to the patient's face and about the nose or a device comprising a pair of nasal delivery members, such as disclosed in U.S. Pat. No. 5,687,715, issued to Landis et al. The containment housing of the apparatus includes a first chamber for receiving breath exhaled by the patient and a second chamber for storing fresh air for delivery back to the patient at a predetermined time during the patient's breathing cycle. The chambers are expandable and operatively interconnected whereby expansion of the first chamber causes expansion of the second chamber. An energy storing means is provided within the containment housing which is adapted to operate, at the moment of completion of the patient's breath exhalation, to contract both of the expandable chambers and cause a momentary burst of pressurized airflow to be ejected from the second chamber and through the nasal device to the patient's airway. The pressurized airflow is only momentary, whereby completion of air inhalation occurs naturally and voluntarily by the patient.

[0014] Details of the method of the present invention and the elements and structural characteristics of several embodiments of the apparatus will become apparent from the ensuing detailed description when considered in reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a schematic representation which illustrates both the method and basic apparatus for practicing the present invention.

[0016]FIGS. 2 and 3 are schematic representations which illustrate the physical principles underlying the method and basic operation of the apparatus of the present invention.

[0017]FIGS. 4 and 5 are elevational views in vertical section of a bench-test embodiment of the apparatus of the present invention.

[0018]FIG. 6 is an elevational view in vertical section of the apparatus which incorporates the structural and operative characteristics first disclosed in FIGS. <b>1</b>-<b>5</b>.

[0019]FIG. 7 is an elevational view in partial vertical section illustrating an alternative embodiment of the apparatus of the present invention.

[0020]FIG. 8 is an elevational view in vertical section illustrating still another alternative form for the apparatus of the present invention.

[0021]FIG. 9 is a perspective view of certain components intended for use in still another embodiment of the present invention.

[0022]FIG. 10 illustrates a novel or ancillary use contemplated for the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023]FIG. 1 schematically illustrates an assembly <b>10</b> including an airflow generator <b>12</b>, an electromagnetic solenoid <b>14</b>, a dual valve assembly <b>16</b>, a normally-open electrical switch <b>18</b>, and a mask <b>20</b>. The airflow generator <b>12</b> may be a blower or fan of the type used to produce a pressurized airflow. The solid line arrows mark the air stream flow path, beginning with ambient air drawn into the airflow generator as indicated by arrow <b>22</b>. The electric current to operate the flow generator is supplied through conductors <b>24</b> and <b>26</b>, which also supply current to solenoid <b>14</b> through switch <b>18</b>. The airflow generator <b>12</b> is intended to operate continuously whereby a constant head of pressurized air is maintained to the solenoid <b>14</b>. However, the solenoid <b>14</b> is normally closed and will permit air passage there through to the dual valve assembly <b>16</b> only when the solenoid <b>14</b> is caused to open by switch <b>18</b>.

[0024] The dual valve assembly <b>16</b> of FIG. 1 includes a flexible circular diaphragm <b>28</b> and a disc valve <b>30</b> mounted on the diaphragm <b>28</b>. In its relaxed position (not shown), the diaphragm <b>28</b> will cover and seal apertures, such as aperture <b>32</b> and aperture <b>34</b>. The disc valve <b>30</b> is a circular flexible thin rubber membrane which normally seals against the inside surface of the diaphragm <b>28</b> but will flex open in response to pressurized airflow from the solenoid <b>14</b> and allow the airflow to pass through the valve arrangement and thence into mask <b>20</b>.

[0025] It should be noted that the mask <b>20</b> is provided with a normally-closed disc valve <b>36</b> which will respond to inhalation by the patient and open to permit entry of ambient air. The mask <b>20</b> is meant to be worn in sealed relation to the nose of a patient whereby ambient air during inhalation will pass into the mask past valve <b>36</b>. Exhaled breath will cause valve <b>36</b> to close whereby the breath flow will be in the direction of the dotted line arrow <b>38</b> and into the dual valve assembly <b>16</b>. Breath pressure entering the dual valve assembly <b>16</b> causes the disc <b>30</b> to seal against the diaphragm <b>28</b> and stretches the diaphragm <b>28</b> from a sealing linear disposition (not shown) to the position shown in FIG. 1. A spring-biased switch trigger or toggle <b>40</b> extending from switch <b>18</b> is contacted by the outwardly-flexed diaphragm <b>28</b> whereby the toggle <b>40</b> is pivoted from left to right as shown in FIG. 1. This pivoting action of the toggle <b>40</b> sets the switch internally whereby, as the diaphragm <b>28</b> relaxes, the toggle <b>40</b> will pivot back to its original position and, at the same, close internal contacts of the toggle <b>40</b> to complete the electrical circuit to the solenoid <b>14</b>. The solenoid <b>14</b> is thereby caused to cycle open and then immediately re-close after having permitted a burst of pressurized air to move into the dual valve assembly <b>16</b> and past the disc valve <b>30</b> and into the mask <b>20</b>. The pressurized airflow burst is directed into the nasopharyngeal airway of the patient as the patient's inhalation action occurs, and ambient air moves through valve <b>36</b> to allow the patient to complete the breath intake voluntarily. The subsequent exhalation by the patient repeats the described process whereby a pulse or burst of pressurized air is delivered to the mask <b>20</b> and thence to the patient's airway as a function of each breathing cycle.

[0026] Although FIG. 1 broadly illustrates the underlying method of the present invention, it is preferred that the apparatus for practicing the method be contained in a compact housing positioned adjacent the head of the patient and that it is not dependent upon a continuously operating bedside blower or household electrical connection for its energy source. Presently preferred embodiments of the invention involve utilization of dual chambers contained in a compact housing, as illustrated and explained hereinafter with references to FIGS. <b>2</b>-<b>8</b>.

[0027]FIGS. 2 and 3 demonstrate the physical principles underlying the mechanical operation of the several embodiments set forth and hereafter discussed in reference to FIGS. <b>4</b>-<b>8</b>. FIG. 2 shows a pneumatically expandable-contractible exhalation chamber <b>50</b> that becomes inflated by the exhaled air from a patient at a certain pressure above atmospheric pressure so that a top plate <b>52</b> of the chamber <b>50</b>, having an area A1, is raised against a compressible elastic element <b>54</b>. The elastic element <b>54</b> may be a compression spring having a constant K. The total vertical force exerted against the elastic element <b>54</b> is the product exhaled air pressure multiplied by the top plate area A1. The elastic element <b>54</b> is compressed until its downward force equals the upward force of the top plate <b>52</b>. An equilibrium position is obtained when the total upward force equals the spring constant multiplied by a distance d, where d is the distance of movement measuring the shortening of the elastic element <b>54</b>.

[0028]FIG. 3 shows a pneumatically expandable-contractible bolus chamber <b>60</b> that works against an elastic element <b>54</b>¹. The force in the compressed elastic element <b>54</b>¹is then applied to the bolus chamber <b>60</b> that is already filled with fresh air at atmospheric pressure when the exhaled breath is released from chamber <b>50</b>. The elastic element <b>54</b>¹exerts a downward force on a top plate <b>62</b> of the chamber <b>60</b>. The top plate <b>62</b> has an area A2, where A1 (FIG. 2) is greater than A2. The air contained in the chamber <b>60</b> is under a positive initial pressure which is available to create a momentary airflow or bolus capable of relieving an apneic obstruction in a patient's airway. Valve and linkage means (not shown) operatively-connected between chamber <b>50</b> and chamber <b>60</b> would be utilized to mechanically translate the expanding action of chamber <b>50</b> to cause chamber <b>60</b> to simultaneously expand and draw in ambient air, and to allow both chambers to simultaneously expand and draw in ambient air, and to allow both chambers to simultaneously contract when the momentary positive airflow (bolus) has been ejected from chamber <b>60</b>.

[0029]FIGS. 4 and 5 illustrate bench model apparatus for practicing and demonstrating the method of the present invention. FIG. 4 shows a structure or apparatus <b>70</b> defining an exhalation chamber <b>72</b> and a bolus chamber <b>74</b>. In the use of the apparatus exhaled breath from the patient enters the exhalation chamber <b>72</b> through an entry port <b>76</b>. Inboard from the entry port <b>76</b> is a circular semi-flexible silicon disc <b>78</b><i>a </i>which co acts with spaced-apart valve seats <b>78</b><i>b </i>and <b>78</b><i>c. </i>The disc <b>78</b><i>a </i>is movable between a first position, as shown in FIG. 4, to a second position, as shown in FIG. 5, and is responsive to low pressure airflow to change its position. Air enters chamber <b>72</b> through entry port <b>76</b>, causing the disc <b>78</b><i>a </i>to close off an outlet passage <b>84</b> whereby all entering air will flow to the chamber <b>72</b>. Sidewall structure serves as linkage <b>86</b> between the chambers. The expansion of chamber <b>72</b> in response to airflow directed thereto through the entry port <b>76</b> causes the linkage <b>86</b> to shift to the left as shown in FIG. 4 also undergoes expansion. Both of the chambers <b>72</b> and <b>74</b> have pleated accordion-like exterior sidewalls <b>88</b> and <b>90</b> which facilitate expansion of the chambers. As chamber <b>74</b> expands from the disposition shown in FIG. 4 to that which is shown in FIG. 5, and in response to the expansion of chamber <b>72</b>, motion of linkage <b>86</b> causes chamber <b>74</b> to expand and draw air in through a central passage <b>92</b>. The airflow through passage <b>92</b> moves past open flapper valve <b>80</b> and into the chamber <b>74</b>. The initial negative pressure in chamber <b>74</b> as it begins to expand causes a valve <b>82</b> to close and valve <b>80</b> to open whereby the chamber <b>74</b> takes in ambient air through the passage <b>92</b>. The expansion of the chambers <b>72</b> and <b>74</b> and the movement of linkage <b>86</b> causes a compression spring <b>94</b> to compress from its expanded disposition shown in FIG. 4 to a contracted position as shown in FIG. 5. When both chambers <b>72</b> and <b>74</b> have fully expanded and the exhalation has ended, the force of energy in the spring <b>94</b> causes the linkage <b>86</b> to shift back from the disposition shown in FIG. 5 to that which is shown in FIG. 4 whereby the volume of air in each chamber is pressurized to create simultaneous discharge airflows. Specifically, the lack of pressure from exhalation and contraction of chamber <b>72</b> causes the valve disc <b>78</b><i>a </i>to close off the port <b>76</b> whereby air from the chamber <b>72</b> will be discharged through the outlet <b>84</b>. Simultaneously, contraction of the chamber <b>74</b> causes valve <b>80</b> to close and valve <b>82</b> to open and eject pressurized air though passage or discharge port <b>96</b>. The bolus of air forced out of chamber <b>74</b> past valve <b>82</b> constitutes air available for delivery to a patient's airway.

[0030]FIG. 6 illustrates apparatus in accordance with the present invention which operates pursuant to the principles explained in reference to FIGS. <b>2</b>-<b>5</b>. The apparatus <b>104</b> shown in FIG. 6 comprises a mask <b>106</b> and a housing <b>108</b>. The housing <b>108</b> is rigidly attached to the mask assembly whereby the mask <b>106</b>, once strapped in operative position against the face of a patient, serves as a housing support. In the embodiment of the invention illustrated in FIG. 6, it is not particularly important that the mask seals against the patient's face because a nasal device <b>110</b> is utilized for airflow communication attachment to the patient's nares as hereafter explained in greater detail. Within the housing <b>108</b> is a bolus chamber <b>112</b> and an exhalation chamber comprised of four compartments <b>114</b>, <b>116</b>, <b>118</b>, and <b>120</b>. The housing <b>108</b> has a central air passage <b>122</b> adapted to take in ambient air through a filter <b>124</b>. The air passage <b>122</b> constitutes a conduit extending from the filter <b>124</b> and centrally through the housing <b>108</b> and into the bolus chamber <b>112</b>. The apparatus <b>104</b> as heretofore described presents a means of practicing the method of the invention in a unitary compact form that is relatively simple in its operational concept. With the mask <b>106</b> disposed against the face and about the nose of the patient, air is inhaled centrally through the housing passage <b>122</b>. Valve structure <b>132</b> opens during inhalation whereby the air moves from the passage <b>122</b> and across the bolus chamber <b>112</b> and thence past the valve structure <b>132</b> and through a conduit <b>126</b> to the patient's airway. The valve structure <b>132</b> constitutes a stretchable diaphragm <b>132</b><i>a, </i>a flexible valve disc <b>132</b><i>b </i>carried on the diaphragm, and opposed valve seats <b>132</b><i>c </i>and <b>132</b><i>d. </i>The valve <b>132</b> is a dual valve structure which normally seals against the valve seat <b>132</b><i>c </i>to prevent passage of air from passage <b>122</b> to and into conduit <b>126</b>.

[0031] The valve structure is a diaphragm <b>132</b><i>a </i>that supports a flexible disc <b>132</b><i>b </i>that normally seals against an opening in the center of the diaphragm <b>132</b><i>a. </i>The valve <b>132</b> allows airflow in one direction only by the peripheral flexure of the disc <b>132</b><i>b </i>away from the diaphragm <b>132</b><i>a, </i>and the diaphragm <b>132</b><i>a </i>is capable of stretching or rolling, in response to airflow from passage <b>122</b>, to passage <b>146</b>. Inhalation by the patient though the nose connection <b>110</b> establishes an ambient airflow into the filter <b>124</b>, across the passage <b>122</b>, and through the valve <b>164</b> and <b>132</b> to the conduit <b>126</b>. Upon exhalation, airflow from the airway of the patient is delivered through conduit <b>126</b> and downwardly into passage <b>146</b>, with the valve <b>132</b> preventing any airflow into bolus chamber <b>112</b>. The exhaled air stream from the patient moves through the passage <b>146</b> and into valve structure <b>148</b> and thence into a manifold or distribution chamber <b>150</b>. The pressurized airflow from the manifold <b>150</b> is distributed through openings <b>152</b> into compartments <b>114</b>-<b>120</b>, which constitute the exhalation chamber.

[0032] The resultant build-up of air pressure within the compartments <b>114</b>-<b>120</b> of the exhalation chamber causes a shift in the internally-disposed rigid linkage <b>162</b>. The linkage <b>162</b> is adapted to shift from a chamber-empty position (not shown) and to the right, as viewed in FIG. 6, to a chamber-filled position. As the exhalation chamber takes in air and expands, ambient airflow causes valve <b>164</b> to open to allow the ambient air to fill bolus chamber <b>112</b>. Termination of the patient's exhaled breath results in a slight back pressure in the manifold <b>150</b>, causing the disc <b>148</b><i>a </i>to shift from its sealed position against valve seat <b>148</b><i>b </i>to a second sealed position against valve seat <b>148</b><i>c. </i>An energy storing means, in the form of compression spring <b>166</b>, acts to push the rigid linkage <b>162</b> from right to left as viewed in FIG. 6, thereby causing contraction of the exhalation chamber and the bolus chamber <b>112</b>.

[0033] This results in the air within the exhalation chamber compartments <b>114</b>-<b>120</b> to be expelled through outlet port <b>154</b>. Air pressure within the bolus chamber <b>112</b> causes valve <b>164</b> to close whereby the bolus of air is forced against the diaphragm <b>132</b> such that disc <b>132</b><i>b </i>will peripherally flex to allow the bolus to proceed into conduit <b>126</b> and thence through the nasal connection <b>110</b> and into the patient's airway. The ambient air previously captured in the bolus chamber <b>112</b> is forced as a pulse or thrust into the patient's airway just as the patient is starting to inhale. The bolus of air delivered to the patient's airway is sufficient to cause the inhalation to begin. The apneic obstruction in the airway is caused to relax whereby the patient finishes the breath inhalation as part of the natural breathing cycle.

[0034] Also illustrated in FIG. 6 is a reservoir <b>170</b> into which medication in liquid form may be stored and allowed to disperse into the bolus chamber <b>112</b>, the rate of dispersal being controlled by a metering device <b>172</b>. Many patients who are afflicted with sleep apnea also suffer asthmatic symptoms, including swelling of mucous membranes and bronchial tube spasms manifested by shortness of breath, whereby gasping causes the individual to awaken. The administration of medication into the air stream and thence into the bronchial tubes during inhalation is now common and can be quite effective in promoting natural sleep. The provision of the reservoir <b>170</b> for this purpose, whereby droplets of medication can be metered into the bolus of air in the chamber <b>112</b>, is an elective option that can be made available to the user of the device illustrated in FIG. 6.

[0035]FIG. 7 illustrates an alternate embodiment of the apparatus of the present invention comprising a unified structure <b>180</b>. The structure <b>180</b> includes a housing <b>182</b> coupled to a mask <b>184</b>. Within the housing <b>182</b> is a bolus chamber <b>186</b> partially defined by a flexible diaphragm <b>188</b>. A nasal device <b>214</b> constitutes a means for attaching the apparatus in flow communication with a patient's airway. The function of apparatus <b>180</b> begins immediately upon it being placed in its operative position, with the nasal device <b>214</b> inserted into the patient's nares. As the patient inhales, ambient air enters through inlet <b>190</b> and moves through passage <b>194</b> and thence into the chamber <b>186</b>. Flapper valve <b>198</b> pivots to an open position during inhalation. Inhalation continues by passage of air through the conduit <b>200</b> and into the patient's airway. Exhaled breath passes out through the conduit <b>200</b> and into the chamber <b>186</b>. A slight pressure is sufficient to close valve <b>198</b> whereby the exhaled breath progresses past open valve <b>202</b> and outwardly through passage <b>204</b>. A pressure-sensitive electrical switch <b>206</b> is caused to close its contacts by the exhaled breath moving thereagainst, completing a circuit to an energy storing means in the form of batteries <b>208</b> that actuate a solenoid <b>210</b>. Closure of the switch <b>206</b> is only momentary and sufficient to energize the solenoid <b>210</b> whereby its plunger <b>212</b> acts against the diaphragm <b>188</b>, causing the diaphragm to flex from right to left as shown in FIG. 7, and then return to its start position. The resulting increased air pressure within the-chamber <b>186</b> is forced through the conduit <b>200</b> and into the patient's airway. Means, in the form of a thumb screw <b>216</b> threaded into an accommodating aperture in the housing <b>182</b>, may be utilized to regulate the intensity of the air pressure bolus within the chamber <b>186</b> by allowing minimal controlled leakage.

[0036]FIG. 8 illustrates apparatus <b>220</b> which utilizes the interaction of permanent magnets to cause delivery of a bolus of air to the patient's airway. The apparatus <b>220</b> comprises a housing <b>222</b> and a mask <b>224</b>. The mask <b>224</b> must, in this embodiment, be of the type that seals tightly about the nose of the patient whereby breathing occurs entirely through the apparatus. Within the housing <b>222</b> is a bolus chamber <b>225</b> partially defined by a flexible rolling diaphragm <b>230</b>. Centrally located on the diaphragm <b>230</b> is a flexible disc valve <b>230</b>A which normally blocks apertures <b>234</b> and <b>236</b> provided in the face of a piston <b>238</b>. The only outlet from the chamber <b>225</b> is a passage <b>240</b> normally closed by a valve structure <b>244</b>. The valve structure <b>244</b> comprises a flexible diaphragm <b>244</b><i>a </i>with openings <b>244</b><i>b </i>therethrough and a centrally-attached flexible disc <b>244</b><i>c. </i>The piston <b>238</b> is mounted to be reciprocal within the housing <b>222</b> from a retracted position, as shown in FIG. 8, to a fully extended position which would be to the left.

[0037] To facilitate its operation, the apparatus <b>220</b> is positioned: usually strapped in place, against a patient's face whereby the nose is within the mask <b>224</b>. Ambient air is inhaled by the patient through an opening <b>246</b>. The inhaled airflow is drawn through the hollow body of the piston <b>238</b> and through the openings <b>234</b> and <b>236</b>. Disc valve <b>230</b><i>a </i>is caused to flex open by the pressure of the inhaled air stream whereby air passes through chamber <b>225</b> and thence through openings <b>244</b><i>b </i>in the valve structure <b>244</b>. Disc valve <b>244</b><i>c </i>is flexed open by the positive pressure of the inhaled air stream. Upon completion of inhalation, the patient exhales, causing the valve structure <b>244</b> to close whereby the exhaled breath is channeled through a conduit <b>250</b> and thence into a rearward chamber <b>252</b> in the housing <b>222</b>. Within the chamber <b>252</b>, the exhaled air stream strikes against a rotatable impeller <b>254</b> having an axle <b>256</b> and radially outwardly-extending blades <b>258</b>. The hub <b>260</b> of the impeller <b>254</b> has a recessed area containing a coil spring <b>262</b>. Attached to the impeller <b>254</b> is a split disc-shaped permanent magnet <b>264</b>. Spaced from the magnet <b>264</b> and attached to the piston <b>238</b> is another permanent magnet <b>266</b>. The magnets <b>264</b> and <b>266</b> are preferably rare earth Neodymium discs, one of which is firmly attached to the hub <b>260</b> of the impeller <b>254</b>, and the other being firmly affixed to the back side of the piston <b>238</b>. Such magnets, made from a Neodymium iron-boron material, have seven to ten times more holding or repulsion force than other magnetic materials. The magnets are magnetically charged to repulse each other whereby, when magnet <b>264</b> is rotated on its axis 180° the repulsive force causes the magnet <b>266</b> to move from right to left as viewed in FIG. 8, thereby causing the piston <b>238</b> to move from its first or starting position to its second or extended position such that diaphragm <b>230</b> is deformably distended in the direction of the mask <b>224</b>.

[0038] As shown in FIG. 8, the magnets <b>264</b> and <b>266</b> are in an equilibrium position, however, when exhaled air from the patient moves through conduit <b>250</b> and thence through the rearward chamber <b>252</b>, the air pressure against the impeller blades <b>258</b> cause the impeller <b>254</b> to rotate 180° until the air stream escapes through housing opening <b>246</b>. The rotation of the impeller <b>254</b> rotates the split magnet <b>264</b> relative to the split magnet <b>266</b> whereby a magnetic repulsive force acting between the magnets causes the piston to move away from the magnet <b>264</b>. A light-duty return spring <b>262</b> disposed about the shaft and bearings of the impeller <b>254</b> returns the impeller <b>254</b> to its starting position whereby the repulsive force between the magnets is neutralized. When the piston <b>238</b> is driven from its first position to its second position within the housing <b>222</b>, the bolus of air contained within the chamber <b>224</b> is driven against and past the valve structure <b>244</b> and thence to the airway of the patient. The apparatus <b>220</b> serves to provide a bolus of air into the patient's airway at the termination of each exhalation by the patient during the patient's breathing cycle and, in each sequential cycle, the patient completes inhalation naturally and without assistance before the next exhalation occurs.

[0039] In view of the description of the operation of the various embodiments of the present invention heretofore presented, it should be apparent to those skilled in the art that the method of the invention may be practiced by the provision of a mechanical variation such as shown in FIG. 9. FIG. 9 illustrates a pair of vanes <b>270</b> rotatably mounted on an axis <b>272</b>. The vanes <b>270</b> can be driven to rotate by exhaled breath coming from a mask <b>274</b> to thereby rotate the shaft or axis <b>272</b> and correspondingly wind an energy-storing device <b>278</b>. At the completion of each exhalation by the patient, a wound spring within the energy-storing device <b>278</b> will then cause the shaft <b>272</b> to counter-rotate whereby an impeller <b>280</b> and planetary gears <b>282</b> will force a pressurized airflow back into the mask and thence into the airway of the patient. The aforedescribed function occurs as an incident of each breathing cycle of the patient.

[0040] A further use of the invention is contemplated as shown in FIG. 10 which would include first and second masks <b>284</b> and <b>286</b> by which a first person <b>288</b> could provide hands-free ventilation to a second distressed person <b>290</b>. For this embodiment, momentary positive air pressure would be provided to the first mask <b>284</b>, an exhalation chamber, and a collection or bolus chamber (not shown) as illustrated in accordance with the invention embodiments herein previously described. The exhalation chamber would receive the exhaled breath of the first assisting person <b>288</b>, and the bolus chamber would be adapted to deliver fresh ambient air to the second distressed person <b>290</b>. With the device <b>292</b> coupled intermediate to the first and second persons, by means of hoses <b>294</b> and <b>296</b>, a pressurized flow of ambient air could be delivered from the assisting person <b>288</b> to the distressed person <b>290</b> as a resuscitation measure.

[0041] While various embodiments of the present invention have been disclosed and described herein, it should be understood that the preferred version of the apparatus is compact, portable, and comparatively inexpensive as compared to prior art devices that utilize large blowers or compressors to achieve a similar function by continuous or bi-level airflow provision. It should be further understood that while the invention has been disclosed and described with reference to specific alternative embodiments, there are variations and modifications which may be introduced that will nevertheless come within the scope and spirit of the invention as defined by the appended claims.