Patent Publication Number: US-9839573-B2

Title: Compact mini air pump for use in intermittent pneumatic compression therapy

Description:
RELATED APPLICATION 
     This application claims the benefit of priority to U.S. Provisional Application No. 61/800,301, filed on Mar. 15, 2013, entitled “Compact Mini Air Pump for Use in Intermittent Pneumatic Compression Therapy”. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to medical and therapy devices. The present invention is more particularly useful as an air pump for use with compression garments in the prevention of deep vein thrombosis. The present invention is particularly useful to prevent deep vein thrombosis during periods of low or no activity to continually circulate blood through a patient&#39;s extremities. 
     BACKGROUND OF THE INVENTION 
     Deep Vein Thrombosis, or “DVT”, is a blood clot (“thrombus”) that forms in a vein deep in the body. A thrombus occurs when blood thickens and clumps together. Most of these thrombi occur in the lower leg or thigh; however, they can also occur in other parts of the body. Thrombi located in the thigh are more likely to break off and cause a pulmonary embolism (“PE”) than clots in the lower leg or other parts of the body. The clots that form close to the skin usually cannot break off and cause a PE due to their reduced size and the reduced pressures exerted on them. 
     A DVT, or a portion of it, can break off and travel through the bloodstream where it can enter the lung and block blood flow. This condition is called pulmonary embolism, which is considered to be very serious due to its likelihood of causing damage to the lungs and other organs and can quite possibly lead to death. This condition affects more than 2.5 million Americans each year and is associated with an estimated 50,000 to 200,000 deaths annually. 
     The venous system is designed to allow for the return of blood to the right side of the heart. Veins are not passive tubes through which blood passes, but are a system that uses muscular compressions, gravity, and inter-venous valves to promote and control the flow of blood through them. The valves are located along the entire length of the vein and ensure that blood only flows in one (1) direction, toward the heart. Blood flow may easily pass through the valve in the direction toward the heart, but when pressure is greater above the valve than below, the cusps will come together thereby closing the valve and stopping the flow of blood away from the heart. 
     The valves consist of two (2) very thin-walled cusps that originate at opposite sides of the vein wall and come together to meet at the midline of the vein. The diameter of the vein is slightly larger just behind a valve where the cusps attach to the vein wall. Due to the larger diameter of the vein and the propensity for blood to collect and stagnate between the valve cusps and the vein wall, thrombi formation in this area is more likely. 
     The most common causes of DVT are venous stasis, blood vessel wall injury, and hypercoagulability. Venous stasis is the reduction of blood flow, most notably in the areas of venous valves, usually caused by extended periods of inactivity. These periods of inactivity minimize the muscular compressions applied to the veins therefore removing the forces used to propel the blood through the veins. This reduction in flow allows the blood to collect and congeal thereby forming a clot. The conditions that contribute to venous stasis include heart disease, obesity, dehydration, pregnancy, a debilitated or bed-ridden state, stroke, and surgery. Stasis has been known to develop with surgical procedures lasting as little as thirty (30) minutes. 
     Vessel wall injury can disrupt the lining of the vein thereby removing the natural protections against clotting. The loss of natural protection will increase the chances of clot formation and the subsequent mobilization of the clot that can lead to a PE. Some of the major causes of vessel wall injury are trauma from fractures and burns, infection, punctures of the vein, injection of irritant solutions, susceptibility to DVT, and major surgeries. 
     Hypercoagulability exists when coagulation outpaces fibrinolysis, which is the body&#39;s natural mechanism to inhibit clot formation. When this condition exists, the chances of clot formation, especially in areas of low blood flow, are greatly increased. Some causes of hypercoagulability are trauma, surgery, malignancy, and systemic infection. A typical treatment is the administration of an anti-coagulant such as of low-molecular-weight heparin. 
     It is recognized that clots usually develop first in the calf veins and “grow” in the direction of flow in the vein. The clots usually form behind valve pockets where blood flow is lowest. Once a clot forms, it either enlarges until it is enveloped, which causes the coagulation process to stop, or the clot may develop a “tail” which has a high chance of breaking off and becoming mobile where it can enter the pulmonary system and become lodged in the lungs. 
     In a patient with DVT, the goals are to minimize the risk of PE, limit further clots, and facilitate the resolution of existing clots. If a potential clot is suspected or detected, bed rest is usually recommended to allow for the clot to stabilize and adhere to the vein wall thereby minimizing the chance of the clot becoming mobile where it can travel to the lungs. A more effective preventative measure is ambulation, which is to walk about or move from place to place. Ambulation requires muscle movement. The muscle movement will provide a continuous series of compressions to the veins thereby facilitating the flow of blood. The continuous flow of blood will reduce or eliminate any areas of stasis so clots do not have a chance to form. For people who are confined to a bed or will be immobile for an extended period of time, leg elevation is recommended. This will promote blood return to the heart and will decrease any existing venous congestion. 
     Graduated compression stockings have also been used to apply pressure to the veins so as to reduce or minimize any areas of low flow in the vein and not allow the collection and coagulation of blood in these low flow areas. The stockings are designed to provide the highest level of compression to the ankle and calf area, with gradually decreasing pressure continuing up the leg. The stockings prevent DVT by augmenting the velocity of venous return from the legs, thereby reducing venous stasis. Typically, stockings are applied before surgery and are worn until the patient is fully able to move on their own. The stockings need to fit properly and be applied correctly. If too tight, they may exert a tourniquet effect, thereby promoting venous stasis, the very problem they intend to prevent. If too loose, the stocking will not provide adequate compression. 
     Another treatment of DVT involves the use of intermittent pneumatic compression (IPC). IPC can be of benefit to patients deemed to be at risk of deep vein thrombosis during extended periods of inactivity and is an accepted treatment method for preventing blood clots or complications of venous stasis in persons after physical trauma, orthopedic surgery, neurosurgery, or in disabled persons who are unable to walk or mobilize effectively. 
     An IPC uses an air pump to inflate and deflate airtight sleeves, or garments, wrapped around the leg. The successive inflation and deflations simulate the series of compressions applied to the veins from muscle contractions thereby limiting any stasis that can lead to thrombi formation. This technique is also used to stop blood clots from developing during surgeries that will last for an extended period of time. 
     In order to deliver proper and safe medical therapy to the patient, the air pump used in IPC systems must have necessary qualities, characteristics, durability and overall performance capabilities. The pump must reliably create a user-specified pressure in the compression sleeve on the patient, and maintain it within a narrow range for a specified time period with minimal variability, in time or pressure, through countless repetitions of inflation and deflation. To avoid issues of medical concern, such as tissue hypoxia or structural damage, the pump must be able to sense over-inflation of the garment beyond the set pressure, and decrease pressure through slight deflation or by signaling the user to make appropriate changes. 
     Additionally, the portability, and thus versatility, of an IPC system is important, and is limited by the air pump, typically due to AC power requirements and/or physical size. In care facility, home therapy and hospital settings the patient typically needs to be moved or transferred between rooms or buildings. Such situations can present a significant period of time during which no compression therapy is occurring, creating an increased risk of clotting, DVT and possible resultant PE. 
     Another version of IPC is the Venous Foot Pump which provides an alternative to the traditional thigh or calf compression device. The foot pump mimics the natural effects of walking and weight-bearing on the circulation in the feet and legs through compressions applied to the foot. 
     PE remains the most common preventable cause of death in hospitalized patients. The deaths are most often a complication resulting from the formation of a DVT and the subsequent PE that may result from it. 
     In light of the above, it would be advantageous to provide a deep vein thrombosis prevention system with an air pump that minimizes the occurrence of deep vein thrombosis formation. It would be further advantageous to provide a deep vein thrombosis prevention system having an air pump that allows medical personnel to customize the compression of limbs being treated to optimize treatments for particular patients. It would be further advantageous to provide a deep vein thrombosis prevention system having an air pump that is compact, portable and powered by its own DC battery or standard AC electricity. It would be further advantageous to provide a deep vein thrombosis prevention system having an air pump that is easy to use, relatively easy to manufacture, and comparatively cost efficient. 
     SUMMARY OF THE INVENTION 
     The compact mini air pump for use in Intermittent Pneumatic Therapy (hereafter known as “mini air pump”) of the present invention includes a rectangular, box-shaped body having a standard AC power cord extending from it, two (2) air supply output ports, and a control and information panel with user-operated buttons and status lights located on its front side. Within the hollow interior of the body is an air compressor, a dual-output electromechanical valve having to two (2) air output tubes, an air pressure sensor, a DC battery power supply, an AC power connection, and an electronic circuit board controlling the mini air pump&#39;s function. The air supply output ports, an extension of the air tubes within the body, supply air to Intermittent Pneumatic Compression (“IPC”) Therapy device garments through flexible air supply tubes. The mini air pump device is sized to be held by one hand for portability. 
     The mini air pump of the present invention is controlled through buttons on the front of the device, which include a power on/off switch, a garment selection switch and a single or dual garment mode switch. Powering on the pump by pressing the power button illuminates a power status light, which has a green or amber color if AC or battery power is being utilized. Pressing the button again turns the pump and the light off. The garment selection button allows a user to select which type of IPC therapy garment is being used, limb or foot. Therapeutic parameters, such as air pressure, vary depending upon whether a foot or a limb (calf, thigh, or arm) is being treated. For example, an air pressure of 40 mmHg may be used when treating a patient&#39;s calf while 80 mmHg may be necessary for foot compression therapy. One (1) of two (2) lights illuminates to indicate which garment type, limb or foot, is currently active. 
     Status and alarm indicators are also located on the front of the mini air pump body. A battery power indicator bar light shows the level of charge remaining. An alarm light illuminates to signal the user if there is a state of continuous, non-cycling pressure (solid light) or over pressure (blinking light) occurring in the IPC garment. A second alarm light blinks or remains solid to show a state of high or low pressure in the garment, respectively. An input/output port located inside the body of the mini air pump allows for connection to a computer for servicing, calibration and program mode adjustments. 
     In use, the IPC therapy garment is worn by a patient on an extremity that is subject to development of thrombosis, particularly deep vein thrombosis, and particularly during surgery or extended periods of inactivity. The deep vein thrombosis prevention garment is wrapped snugly about a patient&#39;s leg, for example. The air supply tube is connected to an input port on the garment and to the air supply output port of the mini air pump of the present invention via industry-standard air tube connectors. The user then presses the power button, and selects the garment type being used by using the garment selection button. Once activated, the mini air pump provides a periodic air supply to the garment through the flexible air supply tube leading to an air chamber in the garment. 
     The air pressure is maintained through the flexible air supply tube, the air filled chamber becomes pressurized to a predetermined pressure, such as 40 mmHg. As the air-filled chamber inflates, it provides additional pressure on the leg of the patient to urge blood flow further upward through the leg. 
     The inflation of the air-filled chamber, coupled with the valves within the venous structure of the limb, creates a peristaltic force on the veins within the limb being treated. Once the air-filled chamber is pressurized to a predetermined pressure, the pressurized air supplied by the mini air pump of the present invention to the flexible air supply tube is discontinued, and the air filled chamber deflates, returning the deep vein thrombosis prevention garment to its fully un-inflated configuration. In this fully un-inflated configuration, blood flows freely through the limb being treated. 
     The inflation and deflation timing cycle of the mini air pump of the present invention is determined by the pressures being utilized, and the speed by which the air chamber of the deep vein thrombosis prevention garment deflates. In order to effectively urge blood flow through deep veins, the timing for the peristaltic effect of the mini air pump and the garment is approximately twenty (20) seconds per cycle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The nature, objects, and advantages of the present invention will become more apparent to those skilled in the art after considering the following detailed description in connection with the accompanying drawings, in which like reference numerals designate like parts throughout, and wherein: 
         FIG. 1  is a top plan view of the mini air pump of the present invention showing a pump body having an AC power cord, a control and information panel, and two air output ports, with one port connected to an air chamber (shown in dashed lines) within a deep vein thrombosis prevention garment via a flexible air supply tube; 
         FIG. 2  is a view of the mini air pump of the present invention being used by a patient for the prevention of deep vein thrombosis, showing the mini air pump of the present invention supplying pressurized air through a flexible air supply tube to a deep vein thrombosis prevention garment wrapped around the patient&#39;s calf; 
         FIG. 3  is a magnified top plan view of the control and information panel on the body of the mini air pump of the present invention with the mini air pump connected to two deep vein thrombosis prevention garments via flexible air supply tubes (shown with dashed lines for reference); 
         FIG. 4  is an exemplary operational diagram for the mini air pump of the present invention showing the interconnection and functional relationships between the components, mechanical and electrical; 
         FIG. 5  is a graphical representation of the air pressure supplied from the mini air pump of the present invention in single-garment mode to one deep vein thrombosis prevention garment, and showing a maximum air pressure to be delivered, and the sequential pressure within the air-filled chamber during an inflation cycle before pressure supplied from the mini air pump is released and the air-filled chamber deflates; and 
         FIG. 6  is a graphical representation of the air pressure supplied from the mini air pump of the present invention in dual-garment mode to two deep vein thrombosis prevention garments, and showing a maximum air pressure to be delivered, and the sequential and alternating pressures within both air-filled chambers during an inflation cycle before pressure supplied from the mini air pump is released and the air-filled chambers deflate. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     Referring initially to  FIG. 1 , a top plan view of the mini air pump of the present invention is shown and generally designated  130 . Mini air pump  130  includes a body  132 , an AC power cord  128 , and two (2) air output ports  136  and  236 , which are industry-standard quick-disconnect connectors known in the industry to facilitate changing of different devices with the air pump  130 . In a preferred embodiment, the mini air pump  130  of the present invention supplies air through a flexible air supply tube  110  to one (1) or two (2) deep vein thrombosis prevention garments  100 . The mini air pump  130  of the present invention equipped with only one (1) deep vein thrombosis prevention garment is shown for clarity, and generally designated  100 . Garment  100  is representative of a typical garment used in the therapeutic treatment of deep vein thrombosis on a limb of a patient. Garment  100  is made of a flexible material having an outer side  105  (shown in dashed line) and a front side  107 , and includes a central panel  102 , a right side panel  106  and a left side panel  104 . 
     Flexible air supply tube  110  enters central panel  102  and leads to a single air chamber  112  (shown in dashed line) located between central panel  102  and a flexible cover  108 . This flexible air supply tube  110  having a non-descript length is shown. It is to be appreciated that the length of the air supply tube  110  may vary depending on the particular field of use, and the setting. 
     Air supply tube  110  is connected to the air output port  136  of the mini air pump  130  via a mating quick-disconnect connector  111  on air supply tube  110 . Air is supplied to flexible air supply tube  110  from mini air pump  130  of the present invention. Mini air pump  130  includes a compressor capable of providing a predetermined maximum air pressure that provides a pressure force to fill the air chamber  112 . As will be described in greater detail below, mini air pump  130  can provide air at a predetermined pressure for a predetermined period of time, providing for an inflation and deflation cycle according to the desired therapy parameters. 
     As shown in  FIG. 1 , right side panel  106  of the deep vein thrombosis prevention garment  100  is formed with a number of attachment straps  114 ,  116 , and  118 , with each strap having an integral fastener  120 ,  122 , and  124 , respectively. In common designs within the industry, straps  114 ,  116 , and  118  are provided with the hook portion of a hook-and-loop style fastener  120 ,  122 , and  124 . This hook portion of the hook-and-loop fastener cooperates with the outer side  105  of left side panel  104 , to allow the deep vein thrombosis prevention garment  100  to be positioned about a patient&#39;s limb and secured in place by wrapping the panels  102 ,  104  and  106  around the limb and pressing the fasteners  120 ,  122 , and  124  on straps  114 ,  116 , and  118  firmly against the outer side  105  of panel  104 . The hook-and-loop fasteners attach to the back side of panel  104  to hold the straps  114 ,  116 , and  118  in place. 
     While the mini air pump  130  of the present invention in a preferred embodiment is connected to a deep vein thrombosis prevention garment  100  for use on the limb of a patient, it is to be appreciated that, as will be shown in detail later, the mini air pump  130  is also configured for use on the foot of a patient with corresponding foot-specific garments. 
     Referring now to  FIG. 2 , the mini air pump  130  of the present invention is shown being used by a patient  50  for the prevention of deep vein thrombosis. Specifically, as shown deep vein thrombosis prevention garment  100  is positioned around the lower leg  52 , or calf, of patient  50  and is in communication with mini air pump  130  of the present invention through flexible air supply tube  110 . Deep vein thrombosis prevention garment  100  is positioned around the calf  52  of patient  50  by positioning panels  102  and  104  (shown in  FIG. 1 ) against the patient&#39;s leg, and then wrapping straps  114 ,  116 , and  118  of panel  106  around the calf  52  and securing the straps to the outer side surface  105  of panel  104  with fasteners  120 ,  122 , and  124  (shown in  FIG. 1 ). Mini air pump  130  supplies pressurized air through flexible air supply tube  110  to pressurize the air chamber  112  within the deep vein thrombosis prevention garment  100  during periods of inflation and in reverse direction during deflation, shown by directional arrows  113  and  115 , respectively. This cyclic pressure of an inflation-deflation cycle, in combination with the inter-venous valves present in the circulatory system, provides a peristaltic force on blood within the limb. The peristaltic force creates the near continual movement of blood within the limb being treated, thereby avoiding the formation of deep vein thrombosis. 
       FIG. 2  depicts a patient  50  in a sitting position undergoing deep vein thrombosis prevention treatment on one (1) leg. However, this is merely exemplary of the typical use of the mini air pump  130  of the present invention. Indeed, the mini air pump  130  of the present invention may be used with the patient  50  virtually in any position. The portability of mini air pump  130  even allows treatment of a patient who is ambulatory so as to prevent interruption of deep vein thrombosis prevention treatment while the patient goes to the lavatory, for example. Mini air pump  130  may also be used, as mentioned, on foot  54  of patient  50  with a foot-specific garment (not shown). 
     It is also to be appreciated that while  FIG. 2  depicts a patient  50  having one (1) deep vein thrombosis prevention garment  100  on a leg, two (2) deep vein thrombosis prevention garments  100  may be used simultaneously, each inflated and deflated by mini air pump  130  of the present invention. For instance, in a surgery setting, it is commonplace to utilize the mini air pump  130  of the present invention for treatment on both legs. 
     Referring now to  FIG. 3 , a magnified top plan view of the mini air pump  130  of the present invention is shown connected to two deep vein thrombosis prevention garments, generally designated  100  and  200 , by flexible air supply tubes  110  and  210 , respectively (shown by dashed lines for reference). Air supply tubes  110  and  210  attach to air output ports  136  and  236  on body  132  of the mini air pump  130  of the present invention via mating quick-disconnect connectors  111  and  211 , respectively. AC power cord  128  on body  132  is shown not connected to a power source, and as an example, the mini air pump  130  of the present invention is in a battery-powered mode. A user control and information panel, generally designated  131 , is located on the front of body  132  of mini air pump  130 . 
     Body  132  must be hard, durable, and impact resistant in addition to being inexpensive to manufacture. In a preferred embodiment, body  132  is made of a thermoplastic such as polyvinyl chloride (PVC) or acrylonitrile butadiene styrene (ABS). Both PVC and ABS are tough, impact resistant and relatively inexpensive to manufacture. 
     Within user control and information panel  131 , a button on/off switch  140  turns the mini air pump  130  of the present invention on and off. When the pump  130  is powered on by depressing switch  140 , a power status light  144  illuminates amber or green to alert the user the device is operating in DC battery or AC power mode. A battery power indicator bar  146 , composed of several lights, illuminates in a step-wise manner to indicate the approximate battery charge remaining. 
     After powering on, the user selects the type of deep vein thrombosis prevention garment connected to the mini air pump  130  of the present invention by pressing a garment type selection switch  142  to choose the appropriate pressure settings specific for that garment type. Garment type selection switch  142  toggles between programs for a limb or foot garment, and displays the current selection by illumination of a limb status light  148  or a foot status light  150 , respectively. Initially, as a default setting, the limb status light  148  blinks to indicate mini air pump  130  is set for pressurizing limb-type garments. The user has several seconds to press garment type selection switch  142  to select the foot-specific pressure settings before switch  142  is locked and no further selection is possible without restarting the mini air pump  130 . This garment type selection option expands the therapeutic utility of the mini air pump  130  of the present invention as therapeutic pressures and timing of inflation or deflation may vary between the two body regions. 
     A single/dual garment mode selector button  141  allows the user to choose whether one (1) or two (2) deep vein thrombosis prevention garments are connected to the air output ports  136  and  236  of mini air pump  130  of the present invention. Illumination of a single garment mode status light  156  signifies the mini air pump  130  is in single garment mode, and air is pumped only through air output port  136  to garment  100  via flexible air supply tube  110 . If single garment mode status light  156  is unlit, the pump  130  is in dual garment mode, and two (2) garments,  100  and  200 , are pressurized through air output ports  136  and  236  and air supply tubes  110  and  210 , respectively, as shown in  FIG. 3 . 
     Within the user control and information panel  131  of mini air pump  130  of the present invention shown in  FIG. 3 , two (2) alarm status indicators, a Constant Pressure/Over Pressure (CP/OP) alarm light  152  and a Low Pressure/High Pressure (LP/HP) alarm light  154 , are shown. These lights communicate to the user improper system function of the mini air pump  130 , air supply tubes  110  and  210 , and deep vein thrombosis prevention garments  100  and  200 . When a constant air pressure is detected within the system, the CP/OP alarm light  152  will illuminate as a solid light. The CP/OP alarm light  152  will blink, if there is a detection of over-pressure in the system. Constant, non-cycling air pressure may occur if there is a failure in deflation of deep vein thrombosis prevention garment  100  or  200 , thus creating a possible situation of medical concern, as blood stasis and subsequent clotting within the body part being treated can result. Over-pressure of the garment  100  or  200  results when the air pressure within the system exceeds the preset therapeutic level by a predetermined amount. Excessive air pressure can cause tissue damage in the patient  52 . Some possible causes of over-pressure may be failure of air pressure regulation by mini air pump  130  or external compression of the deep vein thrombosis prevention garment  100  or  200  by the patient  50 . 
     The Low Pressure/High Pressure (LP/HP) alarm light  154  illuminates as solid or blinking when a low or high air pressure is detected within the system, respectively. Low air pressure can occur for many reasons, such as low battery power, air pump  130  failure, a leaking or improperly connected air supply tube, or a leaking compression garment  100  or  200 . High air pressure may often be a sign of a kinked air supply tube  110  or  210 . 
     It is to be appreciated that the alarm limits for illuminating the alarm lights, CP/OP  152  and LP/HP  154 , may vary depending upon which garment type is chosen, as the therapeutic pressures and thus the limits differ between limb and foot treatment options. 
     Referring now to  FIG. 4 , an exemplary operational diagram of the mini air pump  130  of the present invention is shown. Air is routed by a dual-output electromechanical switching valve  198  from a single air compressor  186  through a connector air tube  187  and into an air output tube- 1   192  or an air output tube- 2   292 . Air output tubes  192  and  292  connect to air output ports  136  and  236 , respectively (shown in  FIGS. 1-3 ) on body  132  of mini air pump  130  of the present invention. Air from air output tube- 1   192  and air output tube- 2   292  is fed back through sensor air tubes  194  and  294 , respectively, to a pressure sensor  182  for monitoring. 
     The mini air pump  130  of the present invention can be powered by either an AC power source  190  or a DC battery  188  with the AC source  190  overriding the battery  188 , if the pump  130  is plugged into an AC electrical outlet. In a preferred embodiment, the battery is rechargeable with charging and overall power maintenance performed by a power controller  180 . 
     A controller  172  regulates system air pressure and manages inflation/deflation timing of deep vein thrombosis prevention garments  100  and  200  (not shown) through a timer  174 , a memory  178 , pressure sensor  182 , and the power controller  180 . Memory  178  stores program information including maximum and minimum air pressure levels as well as timing presets for the two (2) user-selected garment types, limb or foot, which have differing treatment parameters. Timer  174  creates periodicity of inflation/deflation cycles, the duration of inflation and deflation, and the duration of time at which therapeutic air pressure is sustained.  FIGS. 5 and 6  will outline the timing cycles in detail. 
     In a preferred embodiment, controller  172  is a microprocessor with integrated memory and timing functions. Controller  172  also coordinates illumination of LED status lights such as power  144 , battery indicator bar  146 , limb  148 , foot  150 , CP/OP  152 , LP/HP  154  and single garment mode  156  through a status light driver  176  based upon the user&#39;s input selection using the power switch  140 , garment type selection switch  142 , and single/dual garment mode selector switch  141 . 
     An input/output (I/O) interface  184  directs input from switches  140 ,  141 , and  142  to controller  172 , and provides input/output access for a remote computer  196  allowing calibration of and program customization changes to pressure and timing settings of the mini air pump  130  through direct access to memory  178 . Memory  178  may also be configured through computer  196  to store real-time usage data such as air pressures and timing points of alarm triggers, for example, over pressure or continuous pressure. 
     In use, the user presses power button  140  placing the mini air pump  130  of the present invention in a powered-on state and illumination of power status light  144  through status light driver  176 . If AC power is utilized, power status light  144  illuminates green in color or else amber if the mini air pump  130  is under battery power. The battery power indicator bar  146  is lit through status light driver  176  to reflect the amount of charge in battery  188 . 
     Next, garment type selection button  142  is pressed by the user to select whether a limb or foot is being treated. Garment type selection button  142  toggles between two (2) program modes stored in memory  178 , which contains the specific timing and pressure parameter settings (detailed in  FIGS. 5 and 6 ). Controller  172  signals, through status light driver  176 , illumination of the appropriate garment type status light, limb  148  or foot  150 , then accesses the appropriate timing and pressure parameters from memory  178 . Single/dual garment mode selector switch  141  is then pressed if the user wants to select single garment mode with corresponding illumination of single garment mode status light  156  by status light driver  176 . Default is dual garment mode with single garment mode status light  156  turned off. 
     Cycle clocking in timer  174  is initiated followed by signaling of power controller  180  to turn on air compressor  186 . Air is pumped from compressor  186  through connector air tube  187  to electromechanical switching valve  198 . 
     In single garment mode, switching valve  198  routes the air to air output tube- 1   192  and air output port  136  (shown in  FIGS. 1-3 ) of the mini air pump  130  of the present invention, which inflates the deep vein thrombosis prevention garment  100  (not shown) via flexible air supply tube  110  (not shown). 
     Feedback from air tube  192  through sensor air tube  194  to pressure sensor  182  allows controller  172  to compare current system pressure to the programmed therapeutic level stored in memory  178 . Controller  172  essentially throttles air compressor  186  through power controller  180  as needed to maintain programmed pressure settings. When an inflation cycle has ended, power controller  180  reduces or cuts power slowing or stopping compressor  186 , and air exits the system in reverse direction through air output tube- 1   192 , and out a dissipation outlet  197  in switching valve  198  until timer  174  clocks the next inflation cycle to begin. 
     In dual garment mode, switching valve  198  routes air in an alternating manner to the two (2) deep vein thrombosis garments  100  and  200  via air output tube- 1   192  and air output tube- 2   292 , respectively. First, air is routed from air compressor  186  by switching valve  198  to air output tube- 1   192  in the same manner as when mini air pump  130  is in a single garment mode, as described above. At the beginning of deflation of garment  100  (not shown), instead of allowing normal system bleeding of the air in air output tube- 1   192  to occur backward through dissipation outlet  197  in switching valve  198 , switching valve  198  closes off flow to dissipation outlet  197  and connector air tube  187 , while connecting the pressurized air output tube- 1   192  with non-pressurized air output tube- 2   292 . Air flows in direction  206  from air output tube- 1   192  into air output tube- 2   292 . This method allows utilization of the pressurized air from one system (that of garment  100 ) in deflation mode to assist beginning the inflation of the opposite, un-pressurized system (that of garment  200 ), helping to achieve a quicker inflation time with decreased power consumption. 
     When pressure sensor  182  detects approximately equal air pressures in sensor air tubes  194  and  294 , or the pressure in the sensor air tubes  194  and  294  reach a level pre-programmed in memory  178 , power controller  180  signals switching valve  198  to connect connector air tube  187  to air output tube- 2   292  and turns on air compressor  186  to finish inflation of garment  200 . Deflation of garment  100  continues through connection of air output tube- 1   192  to dissipation outlet  197  in switching valve  198  to complete one cycle of inflation/deflation. The process repeats with garment  200  in the same manner after it achieves maximum inflation, with deflation occurring first through air output tube- 2   292  in direction  204 , through switching valve  198  and into air output tube- 1   192  to assist with the next inflation cycle of garment  100 . Inflation/deflation cycling in either single or dual garment mode will continue until the power switch  140  is turned off, or power is interrupted. 
     The four (4) alarm states are relayed to the user through status lights  152  and  154 . If comparison of memory  178  programmed settings and pressure sensor  182  readings by controller  172  shows a constant, non-cycling pressure, status light driver  176  illuminates the CP/OP light  152  as solid and non-blinking. If comparison shows system pressure exceeds the programmed maximum allowed pressure, signifying a state of over-pressure, status light driver  176  illuminates CP/OP light  152  as blinking. In a similar comparative method, controller  172  signals illumination of LP/HP status light  154  as solid (LP) or blinking (HP) if air pressure in the system falls below a therapeutic minimum (low pressure) or rises above the therapeutic maximum (high pressure), respectively. 
     In a preferred embodiment, air compressor  186  is of a design known in the art and energy efficient. Pressure sensor  182  is of a design known in the art and can, in a preferred embodiment, be a strain gauge or other pressure-sensing device. 
     Referring now to  FIG. 5 , a graphical representation of the air pressure supplied from the mini air pump  130  of the present invention to the deep vein thrombosis prevention garment  100  during single garment mode operation is shown and generally designated  250 . Graph  250  includes a vertical Air Pressure axis and a horizontal Time axis. This graph  250  depicts a typical inflation and deflation cycle that occurs from the mini air pump  130  of the present invention when pump  130  is set to pressurize only one (1) deep vein thrombosis prevention garment  100 . 
     Graph  250  includes a primary supply air pressure curve  252  which corresponds to the air provided by mini air pump  130  to flexible air supply tube  110  (shown in  FIGS. 1-3 ). This air supply begins at the start of the inflation cycle and rises to a preset, therapeutic air pressure  254 . Preset therapeutic air pressure  254  is approximately equal to maximum (MAX) and minimum (MIN) desired therapeutic pressures  256  and  255 , respectively (shown by dashed lines). A fluctuating air pressure curve  266  exemplifies how mini air pump  130  of the present invention maintains preset therapeutic air pressure  254  within this therapeutic range by increasing or decreasing compressor  186  (shown in  FIG. 4 ) air output as needed. 
     An absolute air pressure (ABS MAX) is an overall maximum pressure  268  (shown by dashed line) that corresponds to an absolute maximum allowed pressure within air chamber  112  (shown in  FIG. 1 ) of the deep vein thrombosis prevention garment  100 , the maximum pressure medically safe, or any other maximum value utilized in the art to ensure safe operation of the mini air pump  130  of the present invention. ABS MAX  268  is the air pressure set point above which the mini air pump  130  of the present invention signals an alarm of over pressure. 
     In the mini air pump  130  of the present invention, the preferred maximum pressure for a deep vein thrombosis prevention garment is 40 mmHg for limb and 80 mmHg for foot treatment. It is to be appreciated, however, that different air pressures may be utilized for differing applications, treatment positions, duration of treatment, and other factors known and considered in the art. 
     The inflation cycle is complete once the air chamber  112  of deep vein thrombosis prevention garment  100  has had sufficient time to inflate. Following the inflation cycle, a delay  258  may be utilized to maintain a constant pressure on the limb  52  (shown in  FIG. 2 ) to provide time for the blood to flow through the limb  52 . Following any delay, the deflation cycle begins and the pressure  260  in mini air pump  130  and air supply tube  110  decreases to zero (as shown in  FIGS. 1-2 ). 
     As the decrease in pump and supply tube pressure  260  occurs, the pressure  262  in air chamber  112  likewise returns to zero in substantially the same time. Once this inflation and deflation cycle is complete, a delay  264  may be inserted prior to beginning the next inflation and deflation cycle. 
     Using the mini air pump  130  of the present invention, the time for a complete inflation cycle, deflation cycle and delay is approximately twenty (20) seconds. It is to be appreciated, however, that various cycle times may be implemented in order to accommodate various air bladders, treatment protocol and limb size. 
     As a result, the mini air pump  130  can be cycled three (3) times every minute in order to provide a continuous force to create the desired peristaltic effect. It is to be appreciated that the specific period for a complete cycle may be changed depending on the size of the limb or foot being treated, the pressure desired, and the peristaltic forces necessary to minimize the likelihood of the development of a thrombosis. 
     Referring now to  FIG. 6 , graphical representations of the air pressure supplied from the mini air pump  130  of the present invention to deep vein thrombosis prevention garments  100  and  200  during dual garment mode operation are shown and generally designated  450  and  480 , respectively. Graphs  450  and  480  include a vertical Air Pressure axis and a horizontal Time axis. These graphs  450  and  480  depict typical inflation and deflation cycles that occur from this embodiment of mini air pump  130  of the present invention. Specifically, graph  450  depicts the pressure and timing of air supplied by mini air pump  130  during the inflation/deflation of garment  100 , and graph  480  depicts the pressure and timing of the air supplied by mini air pump  130  during the inflation/deflation of garment  200 . Graphs  450  and  480  are placed together for comparison since they share the same timing signature. 
     Graph  450  includes a primary supply air pressure curve  452  which corresponds to the air provided by air compressor  186  (shown in  FIG. 4 ) of mini air pump  130  to flexible air supply tube  110  (shown in  FIGS. 1-3 ) via air output tube- 1   192  (shown in  FIG. 4 ). This air supply begins at the start of the inflation cycle and rises to a preset, therapeutic air pressure  454 . Similarly, graph  480  includes an air pressure curve  482  which corresponds to the air provided by air compressor  186  of mini air pump  130  to flexible air supply tube  210  (shown in  FIG. 3 ) via air output tube- 2   292  (shown in  FIG. 4 ). This air supply also begins at the start of an inflation cycle and rises to preset, therapeutic air pressure  484 . 
     Preset therapeutic air pressures  454  and  484  are approximately equal to maximum (MAX) desired pressures  456  and  486 , and minimum (MIN) desired therapeutic pressures  455  and  485 , respectively (shown by dashed lines). Pressures above MAX  456  and  458  or below MIN  455  and  485  levels will cause mini air pump  130  to signal an alarm of high or low pressure, respectively. In the event that the pressure measured exceeds the maximum pressure as determined by a preset pressure value, the device can be set to immediately vent the overpressure, or to turn off the device. 
     An absolute air pressure (ABS MAX) is an overall maximum pressure  468  and  498  (shown by dashed lines) that corresponds to an absolute maximum allowed pressure within deep vein thrombosis prevention garment  100  and  200 , respectively, the maximum pressure medically safe, or any other maximum value utilized in the art to ensure safe operation of the mini air pump  130  of the present invention. ABS MAX  468  and  498  are air pressure set points above which the mini air pump  130  of the present invention signals an alarm of over pressure. 
     With single/dual garment mode selector switch  141  (shown in  FIGS. 3-4 ) turned off to select single garment mode, the inflation/deflation cycle of the deep vein thrombosis prevention garment  100  follows the graph shown in  FIG. 5 . 
     When single/dual garment mode selector switch  141  is turned on to select dual garment mode the inflation and deflation of garments  100  and  200  proceeds as follows with inflation beginning first with air output tube- 1   192  and garment  100 . 
     Looking at graph  450 , the inflation cycle is complete once the deep vein thrombosis prevention garment  100  has had sufficient time to inflate, and is designated by time period  470 . Following the inflation cycle, a delay may be inserted at the end of time period  470 , as described in  FIG. 5 , but is not represented here. 
     Following inflation, the deflation cycle begins, and the pressure  462  in the system of air output tube- 1   192  and garment  100  decreases to zero during time period  472 . Simultaneously, the system of air output tube- 2   292  and garment  200  begins inflation as shown by curve  482  in graph  480 . This inflation cycle is complete when air pressure in deep vein thrombosis prevention garment  200  reaches therapeutic level  484  at the end of time period  472 . 
     A delay  473  in graph  450  occurs naturally between the end of garment  100  deflation and the beginning of its next inflation cycle shown by curve  453  in time period  474 . This delay  473  exists as the time differential between garment  100  ending its deflation cycle and garment  200  finishing its inflation cycle, and is variable depending upon set timing parameters. 
     During time period  474 , as garment  100  is in its next inflation cycle, garment  200  begins its deflation cycle and pressure  492  returns to zero. Again, as shown on graph  480 , a delay  476  occurs between the end of the garment  200  deflation cycle and completion of the garment  100  inflation cycle shown by curve  453 . 
     While there have been shown what are presently considered to be preferred embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope and spirit of the invention.