Abstract:
Methods and apparatus for providing rapid compression to at least one appendage positioned within an inflatable sleeve are disclosed. Rapid compression is provided by filling the inflatable sleeve containing the appendage with a gas. A portion of the gas is then repeatedly withdrawn and inserted back into the inflatable sleeve to apply a compression therapy to the at least one appendage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of the filing date of provisional application No. 60/479,315 entitled “RAPID COMPRESSION APPARATUS AND METHOD” filed Jun. 18, 2003, the contents of which are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention relates to the field of medical devices and, more particularly, to methods and apparatus for providing rapid compression therapy treatments to at least one appendage, e.g., an arm or a leg, of a body. 
   BACKGROUND OF THE INVENTION 
   Compression therapy systems are used in several medical applications to apply rapid compressions to one or more appendages (e.g., arms, hands, legs, and feet) of a body. For example, compressions therapy systems are used to treat chronic wounds by applying pressure to an appendage having wounds to improve circulation around the wounds, or to improve blood circulation to treat angina or congestive heart failure (CHF), e.g., as in enhanced external counterpulsation (EECP) devices. 
   In a conventional compression therapy system, a large compressor compresses air for storage in a storage tank. Moderate amounts of air from the storage tank are then delivered to an inflatable sleeve containing an affected appendage in rapid low pressure bursts to apply compression to the appendage. After each burst of air fills the inflatable sleeve, the inflatable sleeve is opened to release the air and, thus, remove the compression from the appendage. The compressor and storage tanks needed in such systems are loud, bulky, and expensive, making them unsuitable for use in the home. In addition, because of the volume of air required for conventional compression therapies, these systems are generally unable to treat more than one appendage at a time using power from ordinary household outlets (e.g., 1500 watts or less at 120 volts AC). 
   There is an ever present desire for more convenient and economical medical equipment. Accordingly, rapid compression apparatus and methods are needed that are not subject to the above limitations. The present invention addresses this need among others. 
   SUMMARY OF THE INVENTION 
   The present invention is embodied in methods and apparatus for providing rapid compression to at least one appendage positioned within an inflatable sleeve. Rapid compression is provided by filling the inflatable sleeve containing the appendage with a gas. A portion of the gas is then repeatedly withdrawn and inserted back into the inflatable sleeve to apply a compression therapy to the at least one appendage. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is best understood from the following detailed description when read in connection with the accompanying drawings, with like elements having the same reference numerals. When a plurality of similar elements are present, a single reference numeral may be assigned to the plurality of similar elements with a small letter designation referring to specific elements. When referring to the elements collectively or to a non-specific one or more of the elements, the small letter designation may be dropped. This emphasizes that according to common practice, the various features of the drawings are not drawn to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures: 
       FIG. 1  is a block diagram of an exemplary rapid compression system in accordance with the present invention; 
       FIGS. 2A and 2B  are illustrations of exemplary inflatable sleeves for applying pressure to an arm and a leg, respectively, in the exemplary rapid compression system of  FIG. 1 ; 
       FIG. 3  is a flow chart depicting exemplary steps for applying pressure to an appendage in accordance with the present invention; 
       FIG. 4  is a block diagram of an alternative exemplary rapid compression system in accordance with the present invention; and 
       FIG. 5  is a block diagram of an alternative exemplary rapid compression system in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a block diagram of an exemplary rapid compression system  100  for applying rapid compression therapies on a patient&#39;s appendage (e.g., arm, leg, foot, hand, etc.). The illustrated rapid compression system  100  includes a rapid compression device  102  and at least one inflatable sleeve (represented by inflatable sleeve  104 ) for receiving an appendage. In general overview, an appendage is positioned within the inflatable sleeve  104  and the inflatable sleeve  104  is filled with gas (e.g., air) to apply pressure to the appendage. The rapid compression device  102  then cyclically withdraws a portion of the gas from the inflatable sleeve  104  to reduce the pressure on the appendage and reinserts the withdrawn portion of gas back into the inflatable sleeve  104  to increase the pressure on the appendage. Thus, the gas is reused to increase efficiency rather than being vented to the atmosphere during each cycle as in conventional systems. 
   The present invention is now described in greater detail.  FIG. 2A  depicts an exemplary inflatable sleeve  104   a  for applying compression therapies to an arm and  FIG. 2B  depicts an exemplary inflatable sleeve  104   b  for applying compression therapies to a leg. The illustrated inflatable arm sleeve  104   a  is tubular in shape and is configured to receive an arm. The inflatable arm sleeve  104   a  includes a relatively soft inner layer  200  that inflates to conform to the appendage and a relatively rigid outer layer  202  that prevents the inner layer  200  from expanding outward when the inner layer  200  is inflated. The inner layer  200  at least partially defines a volume for receiving the gas, where the volume may be reduced by forces produced by the outer layer  202  and the appendage positioned within the sleeve  104   a . The pressure of the gas within the volume of the inner layer  200  is physically applied to the appendage by the inner layer  200 . The outer layer  202  may be a nylon fabric laminated with a polyurethane film. 
   In an exemplary embodiment, the inner layer  200  has a single inflatable section  206  with an opening  208  for coupling to the rapid compression device  102  ( FIG. 1 ) to exchange gas. In this embodiment, the signal inflatable section  206  at least partially defines the volume for receiving the gas. In an alternative exemplary embodiment, the inner layer  200  may have a plurality of inflatable sections (represented by inflatable sections  206   a ,  206   b ,  206   c , and  206   d ) and a plurality of openings (represented by  208   a ,  208   b ,  208   c , and  208   d ). In this embodiment, a plurality of volumes (section volumes) for receiving the gas are defined by the sections. The plurality of inflatable sections may be physically coupled to or physically separated (either partially or fully) from one another. One or more of the plurality of inflatable sections may correspond to one or more outer layer sections (represented by outer layer sections  202   a  and  202   b ), which may be physically coupled to or physically separated (either partially or fully) from one another. 
   The sleeve  104   a  may have an optional zipper  210  to minimize application and removal time of the sleeve on the arm. In addition, the sleeve  104   a  may have one or more optional valves (represented by valve  212 ) to release excess pressure and to deflate the sleeve  104   a  for removal from the appendage and for storage. Inflatable leg sleeve  104   b  is similar to inflatable leg sleeve  104   a , except in shape, with similar element being identically numbered, and will not be described in further detail. 
   Referring back to  FIG. 1 , the rapid compression device  102  includes a cylinder  106  and a sliding piston  108 . The cylinder  106  has a first end  106   a  and a second end  106   b . A piston seal  110  is positioned around the perimeter of the piston  108  to form a seal between the edges of the piston  108  and an interior wall  106   c  of the cylinder  106 . In an exemplary embodiment, the cylinder  106  and the piston  108  each have a circular cross section. In alternative exemplary embodiments, the cylinder and piston may have cross sections with other shapes, e.g., oval, square, rectangular, triangular, or essentially any shape. 
   A piston driver  112  is coupled to the piston  108  to move the piston  108  back and forth within the cylinder  106  to alter the volume of a pressure cavity  114  within the cylinder  106  defined by the second end  106   b  of the cylinder  106  and the piston  108 . In the illustrated embodiment, the piston driver  112  is coupled to a controller  134  (described below), which controls the piston driver  112  to move/position the piston  108  within the cylinder  106 . In an exemplary embodiment, the piston driver  112  is configured to operate using power available from a conventional household outlet, e.g., 1500 watts or less at approximately 120V AC. In an alternative exemplary embodiment, other power sources may be used. A suitable piston driver for use with the present invention will be understood by one of skill in the art from the description herein. 
   The pressure cavity  114  is coupled directly to the inflatable sleeve  104  such that altering the volume of the pressure cavity  114  alters the pressure of the gas in the volume defined by the inflatable sleeve  104 . In an exemplary embodiment, the valve  208  of the inflatable sleeve  104  is coupled to the pressure cavity  114  of the cylinder  106  via a gas transport connector  116  such as a flexible tube or other suitable means for transporting gas between the sleeve  104  and the rapid compression device  102 . The gas transport connector  16  may have a diameter that permits the pressure of gas within the cavity  114  of the rapid compression device  102  and the pressure of gas with the inflatable sleeve  104  to equalize rapidly (e.g., within about 50–100 milliseconds). In an exemplary embodiment, the gas transport connector  116  is a flexible tube having a diameter of about at least two inches. 
   When the piston  108  is inserted into the cylinder  106  (i.e., moved toward the second end  106   b ), the volume of air within the cavity  114  goes down, thereby increasing the pressure in the cavity  114  and in the inflatable sleeve  104  coupled to the cylinder  106  due to a decrease in the combined volume of the cavity  114  and the inflatable sleeve  104 . When the piston  108  is extracted from the cylinder  106  (i.e., moved toward the first end  106   a ), the volume of air within the cylinder  106  goes up, thereby decreasing the pressure in the cavity  114  and in the inflatable sleeve  104  coupled to the cylinder  106  due to the restored combined volume of the cavity  114  and the inflatable sleeve  104 . 
   The illustrated rapid compression device  102  further includes a rear position sensor  118 , a front position sensor  120 , and a pressure sensor  122 . In an exemplary embodiment, the rear position sensor  118  defines the maximum extraction point for the piston  108 , the front position sensor  120  defines the maximum insertion point for the piston  108 , and the distance between the sensors  118  and  120  defines a maximum stroke length for the piston  108  within the cylinder  106 . The pressure sensor  122  senses the pressure in the cavity  114 . Suitable position and pressure sensors for use in the present invention will be readily apparent to those of skill in the related arts. 
   In the illustrated embodiment, manual and automatic valves allow the flow of air in and/or out of the cavity  114 . The illustrated embodiment includes a manual release valve  124 , an air release solenoid valve  126 , an excess pressure relief valve  128 , and an air inlet valve  130 . The manual release valve  124  opens manually to allow reduction of the pressure within the cavity  114 . The air release solenoid valve  126  is a controlled device that opens, e.g., in response to signals from a controller, to allow reduction of the pressure within the cavity  114 . The excess pressure relief valve  128  opens when the pressure within the cavity exceeds a predefined value to prevent potentially damaging pressure from developing in the cavity  114 . The air inlet valve  130  is a controlled valve that opens to allow air flow into the cavity  114  when the piston  108  is extracted during an initialization phase, described in further detail below. In exemplary embodiments, an optional pump  132  (shown in phantom) initially supplies air to the inflatable sleeve  104  and/or the cavity  114  within the cylinder  106 . The pump  132  may be a small pump having characteristics such as those found in aquarium pumps. 
   The controller  134  monitors and/or controls the sensors, valves (except for the manual release valve  124  and the excess pressure relief valve  128 ), and piston driver  112  to adjust the pressure/volume within the cavity  114 , which, in turn, adjusts the pressure applied to an appendage within the inflatable sleeve  104 . The controller  134  is programmed to control the pressure within the cavity  114  by changing the position of the piston  108  within the cylinder  106  via the piston drive  112 . In an exemplary embodiment, the controller  134  is programmed with data corresponding to the piston driver  112 , the piston  108 , and the cylinder  106  that enables the controller  134  to determine the relative position of the piston  108  within the cylinder  106 . In certain exemplary embodiments, the controller  134  monitors the rear position sensor  116  and the forward position sensor  118  and does not drive the piston  108  beyond locations corresponding to these sensors to avoid damaging the rapid compression device  102 . In certain other exemplary embodiments, the forward and rear sensors are eliminated and the controller  134  is entrusted with this function. Connection lines between the controller  134  and the various sensors and valves are omitted to avoid clutter within  FIG. 1 . The controller  134  may be a microprocessor, microcontroller, state machine, logic gates, discrete components, integrated circuits, or essentially any device capable of processing signals. A suitable controller for use in the present invention will be readily apparent to those of skill in the related arts. 
   The controller  134  is programmed to vary the pressure/volume within the cavity  114  (and, thus, the inflatable sleeve  104 ) in accordance with various compression therapies. In an exemplary embodiment, the controller  134  is programmed to vary the pressure/volume in the cavity  114  in accordance with a predetermined program at a certain rate for a certain period of time, e.g., between 0 psi and 2 psi at sixty cycles per minute for twenty minutes. In an alternative exemplary embodiment, the controller  134  is programmed to vary the pressure/volume in the cavity responsive to a cardiac signal generated by the heart of a being associated with the appendage. In accordance with this embodiment, the controller may have an input port  136  for receiving the cardiac signal and may increase pressure (reduce volume) of the cavity  114  substantially concurrent with expansion of the heart and decrease pressure (increase volume) of the cavity  114  substantially concurrent with contraction of the heart. 
   The controller  134  may be programmed to apply the pressure in accordance with one or more pressure waveforms, e.g., a trapezoidal waveform, a triangular waveform, a step waveform, etc. Thus, the pressure may vary continuously or may be held for predetermined periods of time, e.g., at the maximum and/or minimum pressure. In certain exemplary embodiments, the pressure, compression rate, time, and/or pressure waveform are set by an operator using a conventional user interface such as a keypad or through a computer interface. 
   The controller  134  may apply different pressure levels during the course of the therapy with the time for each pressure level being programmable as well. For example, the controller  134  may be set to vary the pressure between 0 psi and 1 psi at sixty cycles per minute for ten minutes followed by varying the pressure between 0 and 2 psi at eighty cycles per minute (or responsive to a cardiac signal) for fifteen minutes. In addition, the controller  134  may apply pressure at a variable rate. 
     FIG. 3  is a flow chart  300  of exemplary steps for applying a compression therapy to an appendage using the rapid compression device  102  and the inflatable sleeve  104  of  FIG. 1 . At block  302 , an appendage is positioned with the inflatable sleeve  104 . For descriptive purposes, the invention is described with reference to a single inflatable sleeve, however, multiple inflatable sleeves may be employed for use with multiple appendages. For example, two leg inflatable sleeves and two arm inflatable sleeves may be concurrently used to apply a compression therapy to both arms and legs of a being simultaneously, with the gas for all four inflatable sleeves being controlled by a single rapid compression device  102 . 
   At block  304 , the rapid compression device is initialized. In an exemplary embodiment, the controller  134  (via the piston driver  112 ) positions the piston  108  at a front initialization position  150  (see  FIG. 1 ), which is at or near the front position sensor  120 , and opens all controlled valves, e.g., air release solenoid valve  126  and air inlet valve  130 . In an exemplary embodiment, the front initialization position  150  is spaced from the maximum insertion position of the piston within the cylinder, which is near front position sensor  120 , for reasons that are described in greater detail below. 
   At block  306 , the controller  134  identifies a therapy insertion position for the piston within the cylinder. The therapy insertion position is an initial maximum position that the piston may be inserted into the cylinder during a therapy to develop the maximum therapy pressure. In an exemplary embodiment, the therapy insertion position is the front initialization position. 
   At block  308 , the inflatable sleeve  104  is filled with gas. In an exemplary embodiment, the inflatable sleeve is filled with gas using the rapid compression device  102 , which will be described in further detail below with reference to blocks  310 ,  312 , and  316 . In an alternative exemplary embodiment, the inflatable sleeve is filled with gas using an optional pump  132  instead of, or in addition to, the rapid compression device  102 . 
   At block  310 , the controller  134  moves the piston  108  from the first initialization position  150  to a second initialization position  152  within the cylinder  106  (which is at or near the rear position sensor  118 ) to draw air into the cavity  114 . In an exemplary embodiment, the controller  134  opens the air inlet valve  130  (e.g., to expose the cavity to the atmosphere) and withdraws the piston  108  slowly from the inflatable sleeve to ensure that the cavity  114  is filled with gas (e.g., air) external to the rapid compression device  102  and the inflatable sleeve  104 , rather than gas from the inflatable sleeve  104 . 
   At block  312 , the controller  134  closes the valves and slowly inserts the piston  108  into the cylinder  106  to the first initialization position  150  to fill the inflatable sleeve  104  with gas. In an exemplary embodiment, the controller  134  monitors the pressure within the cavity  114  while the piston  108  is moved forward to ensure that the pressure within the inflatable sleeve  104  does not exceed a predefined maximum therapy pressure level (e.g., 2 psi). If the pressure exceeds the maximum therapy level, the controller may open a valve to release excess pressure as the piston is inserted into the cylinder. 
   At block  314 , the controller  134  determines if a maximum therapy pressure within the cavity with the piston at the therapy insertion position (e.g., first initialization position  150 ) is met. If the maximum therapy pressure in the cavity is met, processing proceeds at block  316 . In an exemplary embodiment, if the desired pressure in the cavity is not met, processing proceeds at block  310  with the steps in blocks  310  and  312  repeated until there is enough air in the cavity  114  and the inflatable sleeve  104  to develop the maximum therapy pressure at the therapy insertion position. For example, if the inflatable sleeve needs 6 liters of air and the rapid compression device  102  can deliver 2 liters of air per stroke, the rapid compression device  102  will cycle at least three times to fill the inflatable sleeve  140 . 
   At block  316 , the controller  134  identifies a therapy extraction position for the piston  108  within the cylinder  106 . In an exemplary embodiment, the controller  134  monitors the pressure within the cavity  114  while the piston  108  is extracted from the cylinder  106  until a minimum therapy pressure is met (e.g., 0 psi). The controller  134  then identifies the position of the piston  108  when the minimum therapy pressure is met as the therapy extraction position. In an exemplary embodiment, the controller identifies the position of the therapy extraction position relative to the therapy insertion position. 
   At block  318 , the rapid compression device  102  withdraws a portion of the gas from the inflatable sleeve into a cavity (e.g., the gas transport connector  116  and/or the cavity  114 ). In an exemplary embodiment, the controller  134  moves the piston  108  from the therapy insertion position to the therapy extraction position to increase the volume of the cavity  114 , thereby drawing a portion of the gas from the inflatable sleeve into the cavity to reduce the pressure in the inflatable sleeve. 
   At block  320 , the rapid compression device  102  inserts the withdrawn portion of the gas from the cavity (e.g., the gas transport connector  116  and/or the cavity  114 ) back into the inflatable sleeve. In an exemplary embodiment, the controller  134  moves the piston  108  from the therapy extraction position to the therapy insertion position to decrease the volume of the cavity  114 , thereby inserting the withdrawn portion of the gas back into the inflatable sleeve to increase the pressure in the inflatable sleeve. 
   At block  322 , the controller  134  determines if the therapy is complete. If the therapy is complete, processing ends at block  324 . If the therapy is not complete, processing proceeds at block  318  with blocks  318  and  320  rapidly repeated until the therapy is complete. In an exemplary embodiment, the controller  134  performs the steps of blocks  318  and  320  to apply the therapy to the appendage such that the piston is cycled rapidly between the first and second therapy positions at a predetermined rate, e.g., between 30 and 120 cycles per minute. In an alternative exemplary embodiment, the piston is cycled responsive to an external signal, e.g., a cardiac signal produced by the heart of a being whose appendage is being treated. In accordance with this embodiment, the controller  134  may control the piston driver  112  such that the piston  108  is inserted into the cylinder  106  to increase the applied pressure substantially concurrent with (or in anticipation of) expansion of the heart and the piston  108  is withdrawn from the cylinder  106  to decrease the applied pressure substantially concurrent with (or in anticipation of) contraction of the heart. 
   In an exemplary embodiments, the controller  134  monitors the pressure in the cavity  114  and increases or decreases the stroke length (e.g., by shifting the therapy insertion position and/or the therapy extraction position) responsive to the monitored pressure such that the desired minimum and maximum pressures are maintained throughout the therapy. For example, if the pressure produced when the piston is positioned at the therapy insertion position is below the maximum therapy pressure (e.g., due to leaks within the system), the controller may reposition the therapy insertion position  150  closer to the maximum insertion position to decrease the volume of the cavity  114  and increase the pressure when piston is at the new therapy insertion position  150   a  (see  FIG. 1 ). 
   After the maximum therapy pressure is developed within the pressure cavity  114  with the piston  108  at the therapy insertion position  150  within the cylinder  106 , the rapid compression device  102  can alter the pressure applied to an appendage within the inflatable sleeve  104  simply by moving the piston within the cylinder between the therapy insertion and extraction positions. Thus, the rapid compression device is able to deliver rapid compressions to an appendage in a more efficient manner by reusing the air rather than releasing the air and then completely replenishing the air in the inflatable sleeve as in conventional systems. 
   Additional details regarding the rapid compression device are now provided. Assuming an inflatable sleeve (hereinafter sleeve) with a 15 liter volume, only 1/15 th  of the volume of the sleeve needs to be displaced by the piston  108  within the cylinder  106  to develop 1 psi of pressure. Typical pressure therapies are performed with a maximum of 1 to 2 psi of pressure. Based on this information, the desired displacement will typically be no more than 2 liters for a 15 liter sleeve to be pressurized at 2 psi. A 5″ diameter piston will have to move only 3.25″ inches to develop 1 psi in a 15-liter sleeve. This distance traveled over a period of 300 milliseconds translates into a system that moves at a speed of approximately 10 inches per second. 
   Exemplary volume calculations follow to illustrate that moving a 5 inch diameter piston 3 and ½ inches will displace 1 liter of air and moving the piston 7 inches will displace 2 liters of air. 
                 5   ″     ⁢           ⁢   diameter   ⁢           ⁢   piston   ⁢           ⁢   has   ⁢           ⁢   an   ⁢           ⁢   area     =     pi   *   radius   *   radius                         ⁢     =     3.14   *   2.5   *   2.5                           ⁢     =     19.63   ⁢           ⁢     sq   .           ⁢   inches                       Volume   ⁢           ⁢   of   ⁢           ⁢     5   ″     ⁢           ⁢     diameter   .     ×     3.5   ″     ⁢           ⁢   length     =     19.63   *   3.5                         ⁢     =     62.72   ⁢           ⁢   cubic   ⁢           ⁢   inches                     1   ⁢           ⁢   cubic   ⁢           ⁢   inch     =     2.54   ⁢           ⁢   cm   *   2.54   ⁢           ⁢   cm   *   2.54   ⁢           ⁢   cm                         ⁢     =     16.387   ⁢           ⁢   cubic   ⁢           ⁢   centimeters   ⁢           ⁢     (   cc   )                       62.72   ⁢           ⁢   cubic   ⁢           ⁢   inches     =     1027.79   ⁢           ⁢   cc                         ⁢     =     1.027   ⁢           ⁢   liters                 
 
   Thus, to displace 1 liter, an approximately 3.5″ translation of a 5″ diameter piston is necessary and to displace 2 liters twice as much translation is necessary, e.g., 7″. The development of suitable piston driver  112  to provide the necessary translation will be readily apparent to those of skill in the art. 
   Exemplary pressure calculations follow to illustrate that displacing one liter of air in a 15 liter inflatable sleeve develops approximately 1 psi and displacing two liters of air in a 15 liter inflatable sleeve develops approximately 2 psi. Pressure, volume and temperature of a given gas are related as shown in equation 1.
 
 p   1   *v   1   /t   1   =p   2   *v   2   /t   2 ,  (1)
 
where p 1 , v 1  and t 1  are pressure, volume and temperature before the compression, respectively, and p 2 , v 2  and t 2  are the pressure, volume and temperature after compression, respectively.
 
   Assuming t 1 =t 2  (which is a valid assumption for low pressure differentials, e.g., 1–2 psi), and atmospheric pressure=15 psi, when we develop 1 psi above atmospheric pressure, we develop actually 16 psi absolute pressure in the inflatable sleeve where it used to be 15 psi. 
   Thus, if we start with 16 liters (15 liters in the inflatable sleeve plus 1 liter in the cylinder) and compress that extra 1 liter into the inflatable sleeve and solve for p 2  we get:
 
 p   1   *v   1   =p   2   *v   2 
 
15*16 =p   2 * 15 
 
p 2 = 16  (or 1 psi above atmospheric pressure)
 
   Thus, adding 1 liter of air to a 15 liter inflatable sleeve raises the pressure by 1 psi and adding 2 liters of air (v 1 =17) raises the pressure by 2 psi. It will be readily apparent to those of skill in the art that pressure may be represented in units other than psi, e.g., millimeters of mercury (1 psi=50 mm of Hg) or inches of water (1 psi=27.7″ of water). 
   Based on the information provided above, a compression therapy can be applied to a single arm or leg in a 15 liter inflatable sleeve (which is a relatively large inflatable sleeve compared to a typical inflatable sleeve having a volume of 5 liters or less) using approximately 300 watts of power. Thus, four appendage (e.g., two arm and two legs) can be treated concurrently using only 1200 watts of power or less, which is well within the power (1500 watts at 120V AC) available in a typical residential home. In addition, the rapid compression device is smaller, cheaper, and quieter than conventional compression devices, which makes them better suited for use in residential homes and in medical facilities. 
   Although the invention is described herein primarily with reference to a single rapid compression device  102  controlling the pressure of an inflatable sleeve  104  having a single inflatable section  206 , the present invention may be applied to inflatable sleeves having multiple inflatable sections. In an exemplary embodiment, as depicted in  FIG. 4 , each of a plurality of rapid compression devices (e.g., RCDs  102   a–d ) are coupled to one or more respective sections (e.g., sections  206   a–d  of inflatable sleeve  104   a ). To regulate the pressure in a section volume of a particular section (e.g., section  206   a ), the controller  134  controls the piston driver of a respective rapid compression device (e.g., RCD  102   a ) to position the piston within the cylinder to regulate the cavity volume of the pressure cavity. This embodiment increases the number of components needed to regulate the pressure of an inflatable sleeve, however, smaller components may be employed due to the workload being divided across the multiple sections. In accordance with this embodiment, the controller may delay one RCD  102  with respect to another to non-uniformly apply pressure to the appendage throughout the sleeve. For example, to encourage fluid flow out of the leg, the controller may be configured to apply pressure to a section of the sleeve surrounding the foot, followed by the ankle, followed by the calf. 
   In an alternative exemplary embodiment, as depicted in  FIG. 5 , a single rapid compression device (RCD)  102  is coupled to a plurality of sections (e.g., sections  206   a–d ) of an inflatable sleeve  104   a . In an exemplary embodiment, the gas transport connector  116  contains gas transport branches (e.g., branches  116   a–d ) to individual sections (e.g., sections  206   a–d ) of the inflatable sleeve  104   a . Controlled valves (e.g., valves  500   a–d ), which may be controlled by the controller  134 , are positioned within the branches. To regulate the pressure of the section volume in a particular section (e.g., section  206   a ), the controller  134  selectively controls the appropriate valve (e.g., valve  500   a ) in conjunction with the piston driver of the rapid compression device  102  to position the piston within the cylinder to regulate the pressure in the cavity volume of the pressure cavity. The controller may generate one or more valve control signals for controlling the valves  500 . The controller  134  may delay opening/closing one valve with respect to another to non-uniformly apply pressure to the appendage throughout the sleeve. 
   In an exemplary embodiment, the same pressure may be applied to multiple appendages and/or sections simultaneously. In alternative exemplary embodiments, different pressures are applied concurrently to different appendages and/or sections. For example, the rapid compression device  102  may apply 75 mm of Hg to a patient&#39;s legs and 50 mm of Hg to the patient&#39;s arms. In an exemplary embodiment, a controlled valve (such as valve  500   a ) is positioned between the rapid compression device  102  and each inflatable sleeve  104  (or individual sections  206  of sleeves) that receives an appendage to enable the application of different pressures. 
   Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. For example, pressure may be sensed in the inflatable sleeve rather than in the cavity within the cylinder of the rapid compression device. Various other modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.