Patent Publication Number: US-10765591-B2

Title: Pulmonary expansion therapy (PXT) devices

Description:
This application is a continuation-in-part of U.S. application Ser. No. 14/865,814, filed Sep. 25, 2015, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present application relates to medical devices for the treatment of atelectasis/airway collapse (AAC). 
     2. Related Art 
     Physiologic breathing in healthy individuals is accomplished by maintaining a negative pressure field inside the pleural cavity. This negative pressure field is enhanced by the downward motion of the diaphragm and upward and outward motion of the rib cage resulting in inspiration. Relaxation of these muscles results in exhalation which is passive, requiring no energy. The apexes of the lungs having a greater negative pressure than inferior lobes due to gravity&#39;s effect on lungs. 
     Atelectasis/airway collapse (AAC) is a serious medical problem that occurs in a number of respiratory conditions caused by a wide range of etiologies. AAC often results in respiratory impairment and/or failure. In a typical case, a patient experiencing AAC is treated with intubation and mechanical ventilation using positive pressure. 
     During positive pressure ventilation of sedated or paralyzed patients, airflow into the lungs takes the path of least resistance. In this scenario, the healthy section of lung presents the path of least resistance as the collapsed and/or obstructed airway restricts airflow. This phenomena is problematic as the medical professional must carefully recruit the atelectatic or sick lung fields without overinflating and thereby damaging the healthy lung. 
     This problem is exacerbated by mechanical ventilation strategies, as recruitment usually involves increasing distending pressures either by increasing peak inspiratory pressures, or by delivering more volume. Both of these techniques increase the likelihood of barotrauma from over inflation of the healthier more compliant lung tissue. 
     To address these problems, negative pressure ventilators have been developed. For example, the earliest negative pressure ventilators developed at the turn of the 20th century relied on negative pressure via the “Iron Lung.” 
     In such a system, a patient is placed into a large steel chamber that forms a sealed, air-tight compartment around the patient&#39;s entire body with just their head outside the iron long as pumps periodically decrease and increase the air pressure within the chamber to cause the lungs to fill with or expel air to mimic the physiological action of breathing. Modern equivalents such as the Hayek Chest Cuirass (provided by Hayek Medical of London, England, UK) employ the same principle using a chest cuirass that covers the chest and abdomen. 
     While these negative pressure ventilators provide certain benefits, they also pose problems of their own. For example, blood pooling in organs such as the liver can occur due to the negative pressure field applied over the abdomen. In addition, because these devices rely on the formation of an air tight seal around the affected lung, they inhibit access to the patient. As another example, these devices are difficult to set-up and keep on a patient, which can be critical in an emergency care situation. 
     Accordingly, a need has long existed for improved systems and methods for lung expansion. 
     SUMMARY 
     A pulmonary expansion therapy (PXT) device may be a handheld device that covers specific lung fields and may generate negative pressure fields locally. The device also may provide vibratory/percussion therapy for airway clearance. The PXT may generate a localized negative pressure field non-invasively to the exterior of the chest wall, thereby increasing the functional residual capacity in underlying lung fields. As a result, increased ventilation and perfusion to the targeted internal lung field may be achieved by creating a decrease in the external barometric pressure relative to the more positive intrinsic airway pressures. The PXT device also may improve lung compliance by enabling a medical professional such as a Respiratory Therapist/Care provider to grab and elevate the chest wall to compensate for the dysfunction of the respiratory musculature responsible for lifting the chest wall during normal breathing. In some embodiments, once a targeted functional residual capacity (FRC) has been established, vibration and/or percussion may be applied with increased effectiveness due to greater oscillatory movement of chest wall. 
     Other systems, methods, features and technical advantages of the invention will be, or will become apparent to one with skill in the art, upon examination of the figures and detailed description. It is intended that all such additional systems, methods, features and technical advantages be included within this summary and be protected by the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
         FIG. 1  shows a perspective view an exemplary pulmonary expansion therapy (PXT) device; 
         FIGS. 2 a  and 2 b    show a plan view of an exemplary membrane for use in a PXT device and a side view of a portion of an exemplary membrane for use in a PXT device, respectively; 
         FIGS. 3A-B  show exemplary inflow tubes for use in a PXT device; 
         FIG. 4  shows an exemplary configuration of negative pressure lumens for use in a PXT device; 
         FIG. 5  shows a perspective view another exemplary pulmonary expansion therapy (PXT) device; 
         FIG. 6  shows a partial view of exemplary positive pressure chambers and negative pressure chambers in a PXT device; 
         FIG. 7  shows a perspective view of another exemplary PXT device; 
         FIG. 8  shows a cutaway of a portion of the exemplary PXT device of  FIG. 7 ; 
         FIG. 9  shows a partial view of a portion of the divider block of the exemplary PXT device of  FIG. 7  with a portion of an exemplary membrane; 
         FIG. 10  shows a partial perspective view of the ribs and percussive diaphragms in the exemplary PXT device of  FIG. 7 ; 
         FIG. 11  shows a plan view of an exemplary double chambered rib of the exemplary PXT device of  FIG. 7 ; 
         FIG. 12  shows a top view of a portion of the exemplary PXT device of  FIG. 7 ; 
         FIG. 13  shows an exemplary positive pressure chamber having percussive diaphragms in the exemplary PXT device of  FIG. 7 ; 
         FIG. 14  shows another exemplary positive pressure chamber having percussive diaphragms; 
         FIG. 15 a    shows an exploded view of another exemplary PXT device; 
         FIG. 15 b    shows a perspective view of the PXT device of  FIG. 15   a;    
         FIG. 16 a    shows a functional diagram of another exemplary PXT device in a first operational mode; 
         FIG. 16 b    shows a functional diagram of the exemplary PXT device of  FIG. 16 a    in a second operational mode; 
         FIG. 16 c    shows a functional diagram of another exemplary PXT device; 
         FIG. 16 d    shows a locking pin for use in the PXT device of  FIG. 16 c   ; and 
         FIG. 17  shows an exemplary negative pressure relief valve for use in an exemplary PXT device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The elements illustrated in the figures interoperate as explained in more detail below. Before setting forth the detailed explanation, however, it is noted that all of the discussion below, regardless of the particular implementation being described, is exemplary in nature, rather than limiting. 
     Referring to the drawings, and initially to  FIG. 1 , an exemplary pulmonary expansion therapy (PXT) device  100  is shown. In the illustrated embodiment, the PXT device  100  may include an inflow tube  110 , an outer shell  120 , a membrane  130 , one or more negative pressure lumens  140 , one or more positive pressure chambers  150 , an outflow tube  160 , and a handle  170 . 
     In some embodiments, the device  100  may also include an airflow source  105 . For example, airflow source  105  may be a gas and/or vacuum source that provides pressures between about 10 pounds per square inch (PSI) to about 120 PSI, preferably between about 25 PSI and about 75 PSI and even more preferably between about 40 PSI to about 60 PSI. Alternatively, or additionally, an electric motor may be used to generate both the negative and positive pressures. This motor may be monitored and controlled electronically to establish and calculate negative pressures and the increased volumes being generated in the positive pressure chambers  150  and/or the negative pressure lumens  140 . As illustrated, a single tube may connect air source  105  to the device  100 . Alternatively, or additionally, multiple tubes may be provided to supply either positive air flow, negative air flow, or both (see, for example,  FIG. 7 ). 
     Other airflow source that provide positive and/or negative pressures of other magnitudes may also be used. For example, in a hospital or home setting, a 50 psi O2 source may be used. In the home care setting, the same source may be used or a compressor may power the percussion. As another example, the negative pressure source may be a portable suction device. Alternatively, or additionally, the device  100  may be coupled to third-party airflow sources. 
     In operation, the inflow tube  110  may introduce air into the one or more positive pressure chambers  150  while the outflow tube  160  may provide a passage for the outflow of air from the one or more negative pressure lumens  140 . The negative pressure lumens  140  may be coupled to the membrane  130  such that, when the device  100  is placed on a patient and as air flows through the device  100 , suction is created causing the membrane  130  to adhere to the patient&#39;s skin. This results in the generation of a localized negative pressure at the exterior of the patient&#39;s chest wall, thereby increasing the functional residual capacity in underlying lung fields. As a result, increased ventilation and perfusion to the targeted internal lung field may be achieved by creating a decrease in the external barometric pressure relative to the more positive intrinsic airway pressures. The PXT device also may improve lung compliance by enabling a medical professional such as a Respiratory Therapist/Care provider to grab and elevate the chest wall to compensate for the dysfunction of the respiratory musculature responsible for lifting the chest wall during normal breathing, as described below. In some embodiments, once a targeted functional residual capacity (FRC) has been established, percussion may be applied with increased effectiveness due to greater oscillatory movement of chest wall, as described below. 
     The overall shape of the device  100  may mimic the size and shape of the human lung. For example, the outer shell  120  may forming a support structure for housing an arched hollow chamber (such as positive pressure chamber  150 ). This chamber  150  may interface with a membrane  130  that may cover and protect the patient&#39;s skin. 
     The shell  120  may be made of plastic and may be shaped similar to the human lung. Like the lung, it may have three segments: an apex segment, a medial segment, and a lower segment. Similarly, there also may be three main pressure points on the skin when the PXT device is in use. For example, the first pressure point may be at or above and resting on the trapezius muscle, the second pressure point may be lateral to sternum on ribcage, and the third pressure point also may rest on the patient&#39;s lateral rib cage, closer to the back posterior side of chest wall. More or less pressure points may be used, and the pressure points may be aligned with other parts of the patient&#39;s body. In some embodiments, the medial and lower segments may be combined and also referred to herein as the lower segment. 
     Depending on the design of the shell  120  and/or the membrane  130 , pressure may be distributed evenly among the segments. Alternatively, or additionally, different pressures may be distributed to one or more segments, and different pressures may be distributed at each segment. 
     In some embodiments, some or all of the rest of the edges of the shell (i.e. other than at these three pressure points) may be recessed so that the three pressure points may absorb the most force when negative pressure is applied to chest. As a result, the patient&#39;s ribcage may be lifted until the recessed edges make contact with the ribcage. At this stage, the patient&#39;s chest may be lifted. Based on shape of the chamber, the chest may be lifted until the channels or slots of the membrane are in a desired position to treat the targeted area of lung. The medical professional then may lift the chest wall in desired directions, thereby improving chest wall compliance and reducing extrinsic airway resistance in hard to ventilate conditions like Respiratory Distress Syndrome (RDS). 
     In some embodiment, the shell  120  includes three, interconnected chambers  150 . Interconnected chambers  150  may enable the medical professional to contour the PXT for a range of chest wall shapes, in order to treat patients with conditions such as scoliosis, kyphosis and the like. 
     An exemplary membrane  200  is shown in  FIG. 2 . The membrane  200  may be made of a silicone elastomeric gel and also may have a thickness between about 0.2 centimeters (cm) and about 8 cm, preferably between about 1 cm and about 5 cm, and even more preferably between about 2 cm and about 3 cm. Other sizes also may be used. 
     In some embodiments, the membrane  200  may have a generally triangular shape to contour with the chest wall. Other shapes may be used. The skin side of the membrane  200  may have an overall concave shape, similar to that of a suction cup. The membrane may have three segments, an apex segment  210 , a middle segment  220 , and a lower segment  230 . Each segment  210 ,  220  and  230  may have its own shape and/or dimensions. For example, an apex segment  210  may be substantially triangular and have a gently concave shape relative to the patient&#39;s chest. In some embodiments, each segment  210 ,  220  and  230  may have a concave shape. 
     The skin side surface of each segment may be further dimpled by concave suction cups  240 . The suction cups  240  may have a circumference between about 0.1 cm and about 2.5 cm, preferably between about 0.5 cm and about 1.75 cm, and even more preferably between about 0.75 cm and 1.25 cm. One or more of the suction cups may provide airflow into a channel for air to escape (i.e. be sucked out into the negative pressure chamber  140 ) via one or more apertures  242 . In the illustrated embodiment, an aperture  242  may be placed in the center of each suction cup  240 . 
     Upon activation of PXT, the membrane  200  may become adhered to the patient&#39;s skin, thereby lending support and protection to the skin by forming a barrier that the skin cannot exceed. In some embodiments, these suction cups  240  may be filled with moleskin type material to form a contiguous, essentially flat concave surface to further protect and support the skin. 
     The interior side (opposite of skin side) of the membrane may be coupled to one or more air channels  244  that may protrude through the surface of the membrane and couple to the negative pressure channels  140 . In some embodiments, a bicuspid valve  250  may be provided near the proximal end of the air channel  244 . The bicuspid valve  250  may provide one-way flow through the channel  244  to assist in maintaining a net negative pressure on skin side of membrane  200 . In addition, the bicuspid valve  250  also may able to generate measured bursts of positive pressures in the interior chamber  150 , thereby oscillating the membrane and chest wall. This oscillation may be more effectively than current forms of chest wall manipulation because, as the skin side is net negative, the PXT device  100  adheres to the chest enabling the medical profession to grab and lift or otherwise manipulate the chest wall as desired. In this manner, the care provider may lift the membrane  200  in multiple directions to mimic respiratory musculature, thereby moving the chest wall in order to focus therapy to specific lung fields. 
     In addition, release valves  260  may be fitted onto the skin side of membrane  200  to disengage the membrane  200  from the patient. For example, the release valves may be operatively coupled to a positive pressure gas source  105  to form a quick release aperture that can evaluate skin integrity at any time during treatment. Reactivation may be triggered by pushing a button (see, for example,  FIG. 7 ) to reactive negative pressure when the membrane  200  is in contact with the skin. 
     In some embodiments, the membrane  200  may be disposable, i.e. discarded after one or a small number of uses. In other embodiments, the membrane may be designed to withstand many uses, such as 100 uses, 1000 uses, 10,000 uses, or more. 
     In some embodiments, the surface area diameter of the portion of the suction cup  240  of the membrane  200  that attaches to a patient&#39;s chest may be smaller than diameter of cup  240 . In such a case, the smaller surface area occupied by the cup  240  may allow for greater contraction of the membrane  200  during tail wagging motion (described below). Thus, rather than having the membrane  200  dimpled with recessed concave cups  240 , the cups  240  may be somewhat external to the membrane  200 , where the connection to the membrane  200  may be slightly larger than the lumen  140  opening  242  in center of cup  240 , similar to that of an octopus&#39; tentacle. This may allow for greater stretching motion, like webbing between the percussion diaphragms (described below). 
     The membrane  200  and/or shell  120  may be custom shaped to an individual patient. To determine the appropriate shape of a given patient, the patient&#39;s chest wall may be measured. Next, the distance from the manubrum of the patient&#39;s clavicle medial to acromion process may be measured used to determine a size of the bottom width of apex chamber. For example, the bottom width of the apex chamber may be about the same size as this distance. The pressure point for the apex may be aligned to rest on the trapezius muscle, and the recessed supports of the lower width of apex chamber may be aligned to come to rest on the patient&#39;s clavicle close to end where clavicle meets the manubrum, and medial to acromion process. 
     By using clavicle as landmark, a medical progression may be able to enhance lung expansion in lung apeces by lifting the clavicle, effectively suspending a patient through negative pressure field generated over lungs. Manual movement of the patient&#39;s shoulder also may be used in conjunction with PXT device manipulation to further enhance lung expansion. 
     Currently, medical professional may suture the clavicles in order to suspend patient, such as children, by their clavicles to effect chest wall compliance. Employing the principles described above, a medical professional may utilize a PXT device to achieve the same goal in a non-invasive manner, improving ventilation of patients as well as perfusion of specific lung fields. In addition, the patient may be placed in various prone positions to apply PXT treatment to any or all lung fields, anterior or posterior, to facilitate and enhance perfusion. 
     Exemplary inflow tubes  110  are shown in  FIGS. 3A and 3B . In  FIG. 3A , an exemplary inflow tube  300  is shown attached to a connector segment  350  via a rotatable joint  340 . The connector segment may couple the inflow tube  300  to a device handle  170 . The inflow tube  300  may also be coupled to a divider block  3580  and include angled divisions  320  to enable movement of the tube  300  as the handle  170  is rotated to provide dynamic contouring of the membrane  130 , as described above. 
     The inflow tube  300  may include a plurality of outlets  310  that provide passages for air inflow into the one or more positive pressure chambers  150 . Each outlet  310  may provide airflow to a single corresponding passage  150  or multiple  310  outlets may provide airflow to the same passage  150 . In the embodiment of  FIG. 3A , the inflow tube  300  may provide the same airflow to each outlet  310 . 
     In the embodiment illustrated in  FIG. 3B , each outlet  310  may be coupled to a corresponding pressure tube  312  that provides airflow to a single corresponding passage  150 . As a result, each chamber  150  may be individually pressurized. Individual pressurization may enable various modes of operation, such as oscillatory patterns like wave patterns, shiatsu or the like, to be provided, either on demand by the medical professional or via a predetermined program. Other modes of operation, such as those described herein, also may be provided. 
     An exemplary divider block  380  may provide various functions in the overall use of the PCT device  100 . First, the divider block  380  may separate the apex segment from the medial segment and/or lower segment to assist in alignment of the PCT device on the patient. For example, the operator may align the divider block  380  on or near a patient&#39;s clavicle to properly align the PXT device. The divider block  380  may provide a structure that receives the inflow tube  310 , allowing it to rotate or the like. In the illustrated embodiment, the inflow tube  310  may be fenestrated to allow for rotation and/or contortion of the membrane. The divider block  380  also may provide a channel for airflow from the negative pressure chambers to the outflow tube. The divider block  380  also may allow the operator to direct and/or control the angle of chest lift. For example, as the divider block  380  is the base of the ball and swivel (see  FIGS. 7-14  and accompanying description below), the angle of the divider block  380  may determine the amount of arch of the spine (inflow tube  310 ) when contouring to chest wall. As such, the positioning of the divider block  380  may allow for targeting specific lung fields. 
     The overall size of the PXT device  100  may vary depending on the size of the patient&#39;s chest and/or lung. For example, a divider block  380  may be about the size of the patient&#39;s clavicle. Thus, for a typical neonatal patient, the divider block  380  may have a width between about 2 centimeters (cm) and about 4 cm and preferably about 3 cm. Similarly, for a typical pediatric patient, a divider block may have a width between about 3 cm and about 7 cm, preferably between about 4 cm and about 6 cm. Finally, for a typical adult patient, a divider block  380  may have a width between about 6 cm and about 12 cm, preferably between about 7 cm and about 10 cm. 
     The sizes of the apex and lower segments may be based on the size of the divider block. For example, the apex may form a triangle having a height between about the half the size and about twice the size as the width of the divider block, and preferably about the same size as the width of the divider block. Similarly, the height of the lower segment may be between about the same size as the width of the divider block and about three times the width of the divider block, preferably between about one-and-a-half times the width of the divider block and about two-and-a-half the width of the divider block, and even more preferably about twice as long as the width of the divider block. In one example of a device for a neonatal patient, the divider block may be about 3 cm wide, a triangularly shaped apex may have a height of about 3 cm, and a trapezoidal lower segment may have a height of about 6 cm. Other shapes and sizes may be used for the divider block, apex, and lower segments. 
     Referring to  FIG. 4 , an exemplary configuration  400  of negative pressure lumens  140  are shown. In the illustrated embodiment, various negative pressure lumens  140  provide cantilever shaped ribs  410   a  and  410   b  that run from the apex segment through the medial segment and out the lower segment. Some negative pressure lumens  140  may act like a backbone  410   a  for the shell  120 , and may form upper interior dome for positive pressure chamber  150 . In some embodiment, the backbone lumens  410   a  may be shorter compared to the three pressure points. Each negative pressure lumen  140  may open to each suction cup for generation of negative field. 
     Each rib  410   b  may be able to rotate, such as for example, between about 60° and about 230° and preferably between about 90° and about 180°. The ribs  410   a  and  410   b  may then come to rest in a balanced manner onto the chest wall, thereby providing contourability to get a seal on misshapen chest walls. Each backbone  410   a  and adjoining rib  410   b  pair then rests on chest wall. The back pressure points are also cantilevered to form vertebrae 1 and the lower width of the shell. For example, the apex backbone might include twenty-four vertebrae, with 8 vertebrae for each segment. As noted above, the internal portion of vertebra is open to each vacuum chamber. Having control of axial rotation of each vertebral opening or fistula to control size of fistula could be used to, for example, manipulate chamber pressures relative to one another. Manipulation of negative pressure of individual chambers may further enhance PXT&#39;s ability to target specific lung areas, as well as to deactivate one chamber due to chest tubes, or indwelling catheters or surgery sites. 
       FIG. 6  shows a partial view of exemplary positive pressure chambers and negative pressure chambers in a PXT device. In some embodiments, the positive pressure chamber  650  may cover the backbone  410   a  and ribs  410   b , whose cantilevering arrangement form an arch or spherical exterior shape to the vacuum chamber segments with varying widths. The vacuum or negative pressure chambers  640  may be defined by a negative pressure chamber membranes  642  that, for example, drape over the backbone  410   a  and ribs  410   b . The positive pressure chambers  650  also may include percussion diaphragms that may interface with the outer shell  120 . The airflow source  105  may be may be connected to a diaphragm that is superior to a vacuum chamber, and overlaps, but is still smaller than vacuum chamber. This arrangement where the diaphragm rests on the external side of vacuum chamber, allows percussion to effect all three segments of chamber in concert and/or in synchrony. The bursts of pressure may oscillate the chest wall. Both the frequency and the amplitude of these oscillations may monitored and/or adjusted based on patient size and tolerance. Both the positive pressure chambers  650  and negative pressure chambers  640  may include pleats  651  and  641 , respectively, or other similar features to allow for expansion and contraction as the pressures within the chambers  650  and  640  varies. Exemplary embodiments showing percussive diaphragms are shown in FIGS.  7 - 15 . 
     In addition, the negative pressures in the negative pressure lumens  140  and/or negative pressure chambers  640  may be monitored and/or adjusted, as may the pressures the between membrane and the skin. For example, a regulator may be provided to control and/or adjust the negative pressures in the negative pressure chambers to reach desired levels. Pressure levels may be output in PSI, millimeter of mercury (mmHg) or the like. 
     Another exemplary PXT device  500  is shown in  FIG. 5 . In the illustrated embodiment, the device  500  includes an inflow tube  510 , connected to divider block  580  housed in a shell  520 . The shell  520  may also house a plurality of positive pressure chambers  550  and negative pressure lumens  540 , which may be operatively coupled to suction cups on a membrane  530 . 
     In the illustrated embodiment, the lumens  540  may form into semi-rigid rubber tubes that may attach to negative pressure source  105 . The lumens may be between about 0.3 cm and about 10 cm, preferably between about 2 cm and about 7 cm and even more preferably between about 3 cm and about 5 cm. 
     Columns defined by the positive pressure chambers  550  and/or the negative pressure lumens  540  may be evenly spaced. The positive pressure chambers  550  may be collapsible/inflatable, depending on the desired negative pressure to grab chest wall. In the illustrated embodiment, each positive pressure chamber  550  is individually addressable. In other words, the pressure in each positive pressure chamber  550  may be modified individually because airflow to each chamber may be modified individually, such as for example, via a specific pressure tube ( 312  in  FIG. 3 ) coupled to the chamber  550 . These chambers  550  also may be oscillated at various pressures and frequencies, such as, for example, after grab is achieved. The chamber  550  may be oscillated in unison and/or may have various rhythmic patterns preset like that of a massage chair. Depending on the length/depth of the suction cups, the pressure chambers may be positioned near or in contact with membrane  530  and/or the patient&#39;s skin. This may enable more effective chest wall manipulation for airway clearance. 
     In addition, the device  500  may also include a front support  580  that provides support for the shell  520 . The front support  590  may have a variable geometry to allow the device  500  to achieve increased contourability of the patient&#39;s chest. For example the front support shell may be telescoping to contract and/or expand as necessary. Alternatively, or additionally, the front support  590  may be made of a flexible plastic material that allows may contract and/or expand in size. Other materials and/or methods may be used to provide a variable geometry front support  590 . 
       FIG. 7  shows a side view of another exemplary PXT device  700 . In the illustrated embodiment, the PXT device  700  may include an inflow tube  710 , an outer shell  720 , a membrane  730 , one or more negative pressure chambers  740 , one or more positive pressure chambers  750 , an outflow tube  760 , a handle  770  and a divider block  780 . The PXT device  700  also may include one or more percussive diaphragms  790 , a pressure release button  772  and a contour sleeve  774  operatively connected to the inflow tube  710  by a cable  776 . The divider block  780  may include a ball  782  that engages a socket  762  to enable rotation of the device  700  and/or contortion of the membrane  730 . 
     The ball joint  782  may enable targeted angling of the divider block  780 . With targeted angling of the divider block  780 , an operator may apply an upward force to either (1) lift upward as when lifting the clavicle or (2) pull chest outward by positioning the divider block  780  at about 90° to the chest, for example, when targeting the lower lobes at the lateral lower lobes. The ball joint  782  swivel also may allow for the spine or to be arched upward like a cat stretching. This contour will be beneficial when targeting the lower lobes by wrapping around lateral lower chest wall. 
     The length of the spinal column (inflow tube  710  and negative pressure lumens  740 ) may affect the amount of arch produced by the spine when the apex chamber and the divider block  780  are pointed downward. 
     The sleeve  774  may act as a control mechanism for twisting the spine. For example, the spine may be rotated by rotating the sleeve  774  over the handle  770 , similar to an accelerator on a motorcycle handle bar. Because the cable  776  is operatively connected to the sleeve (e.g. wrapped around the sleeve  774 ) and connected to the inflow tube, rotation of the spine may mirror the rotation of the sleeve  774 . Alternatively, or additionally, various mechanisms (not shown) may be used to alter the ratio of rotation of the sleeve  774  to rotation of the inflow tube  710 . 
     The ball  782  and socket  762  interface between the divider block  780  and the outflow tube  760  may allow for greater flexibility and/or contortion of the PXT device  700 , as well as strength and support. For example, when lifting the device  700  by applying an upward force on the handle  770 , thereby lifting the patient&#39;s chest, the operator may be able to dynamically adjust the angle of the force to target specific lobes of the patient&#39;s chest. 
     In some embodiment, a similar ball and socket interface may be provided between the divider block  780  and the inflow tube  710 . This arrangement may provide increased flexibility of the device  700  as an assemblage of individual segments; either the percussive chamber vertebrae, the ribcage vertebrae, or cushioned rubber spacers that form a sealed spinal column. The improved flexibility of the spine, and because of the ball and socket interfaces, the inflow tube may form an arc shape when contorted. As the middle of the spine is raised relative to divider block, the device also may better contour to the patient&#39;s lower lobes (when holding device in horizontal position). 
       FIGS. 8 and 9  show additional aspects of the ball and socket interface between the divider block  780  and the outflow tube  760 . A positive pressure column (PPC) may be connected to the handle, preferably at a 90° angle relative to the handle. The PPC at the top may have a sleeve (PPCS) over the handle, as shown in  FIG. 7 . The PPC and PPCS may be fixed at a 90° angle onto the handle and may run parallel to 90° angle of the handle socket above the divider block  780 . 
     As shown in  FIG. 8 , the mechanism of control of vacuum/negative pressure is shown. A button  872  may be located on the handle, such as at or near the 90° bend above the divider block. The button may also be located at other positions on the handle. When the button  872  is depressed, a negative pressure source may be activated and transferred, negatively pressurizing desired features of PXT. This may be achieved, for example, by providing an aperture  876  in the column of the button mechanism  872  that, when depressed lines up with a channel  820  in the outflow tube  860  and thereby a negative pressure source. Other mechanisms to operatively couple the negative pressure source with the negative pressure chambers also may be used. In some embodiments, a locking mechanism (not shown) may be incorporated to allow an operator to toggle between an cony mode in which the negative pressure source is operatively connected to the negative pressure chambers and an ‘off’ mode in which the negative pressure source is disconnected from the negative pressure chambers. Alternatively, or additionally, an operator may be required to hold down the button  872  in order to keep the negative pressure source operatively coupled to the negative pressure chambers. 
     In some embodiments, the button  872  may be positioned over a spring that allows for button to be at rest in up position. The inside of the button column also may include an open port that allows for the introduction of ambient air at barometric pressure. If a situation arises in which the therapy needs to be discontinued, the operator may disengage the negative pressure source by returning the button to the up (or disengaged or ‘off’) position. In response, the chest wall may be released by the device  700 . 
     In some embodiments, a clamp  812  and band  814  or similar mechanism may be used to removably attach the socket  810  of the handle  770  to balls  910  of devices of various sizes. In this manner, the same handle  770  may be used to treat neonatal patients, pediatric patients, or adult patients. Alternatively, a handle  800  may be non-removably attached to the divider block  900  of a particular device  700 . In either case, the strength of the ball and socket joint may be important, as the upward force generated by a Respiratory Care Practitioner (RCP) by lifting upward is transferred to chest wall through this interface. In some embodiments, the outflow tube  760  may for a substantially right angle with the handle  770  to provide for increased strength and directability. Other angles may also be formed between the outflow tube  760  and the handle  770 , such as angles between about 60° and about 120°. 
     The ball  910  of the divider block  900  may include a plurality of lumens  920  or chambers that allow for transfer of negative pressure through the divider block  900  to the negative pressure chambers  740  in the lower segment of the device  700 . In some embodiments, the divider block  900  may include a hollow portion  930  having a height that allows for the membrane  940  to be pulled up into this interior slot  930  when negative pressure is applied, thereby lifting the clavicle the same length and angle. 
     A portion of an exemplary lower segment  1000  is shown in  FIG. 10 . The lower segment  1000  may include a plurality of negative pressure lumens  1040  or ribs, and a plurality of positive pressure chambers that each include at least one percussive diaphragm  1050 . The positive pressure chambers (also referred to herein as percussion chambers) may be individual chambers or shells that may be pressurized (or inflated) individually through outlets in the inflow tube  710 , as discussed above. In some embodiments, the percussion chambers may be substantially diamond shaped. The use of a diamond shape may allow for the device  700  and membrane  730  to move laterally, as the divider block  780  and apex chamber  735  are the head, and spine and lower chambers can be thought of as a tail wagging side to side. 
     As an analogy to help conceptualize the device  700 , the apex chamber  735  and divider block  780  may be considered the head and shoulders of the PXT device  700  while the inferior portions may be referred to as the body and/or tail. To continue the analogy and as noted above, the inflow tube  710  may be considered the spine while the negative pressure chambers  740  may be considered vertebrae. This configuration may allow for lateral movement like the wagging of the tail portion from side to side and the rotator sleeve  774  may allow for rotation of the spine to achieve greater contour to a patient&#39;s chest wall. In the embodiment illustrated in  FIG. 10 , the inflow tube  1010  may include cushioned spacers  1012  that act like discs in the human spine to allow for lateral movement. 
     In operation, as negative pressure is applied to the body/tail of a PXT device  700 , negative pressure chambers  740  are formed within membranes  642  that are provided around the negative pressure vertebrae  740 , which receive support from spine  710 . This is shown, for example, in  FIG. 11 . As illustrated, the negative pressure lumens  1110  may be one of two channels or ribs ( 1110  and  1120 ) of a vertebrae  1100 . An aperture  1112  may be provided, such as at the apex of the inferior rib  1110  to pressurize the negative pressure chambers  740  defined by negative pressure chamber membrane  1130  (shown partially), transferring negative pressure to the membrane  730  for adherence to the chest wall. The superior rib  1120  of the vertebrae may provide negative pressure to create the vacuum effect that enables the membrane/skin interface. 
     The ribs  1110  and  1120  of the vertebrae may be made of flexible material such as rubber or the like to allow for contortion of the device  700  during therapy. Other materials, such as metals or alloys may also be used. In some embodiments, the vertebrae may be fixedly attached to the spine (inflow tube  710 ). For example, notches may be provided in the spine to receive a corresponding portion of a vertebrae. Alternatively, some movement or rotation of the vertebrae  1110  and  1120  relative to the spine  710  may be allowed. The vertebrae  1110  and  1120  may be attached to one another, or may be separate from one another. 
     In operation, as the force generated by the negative pressure is directed toward the patient, and the positive pressure is generating force in the opposite direction, thereby percussing the chest wall, the ribcage (negative pressure chambers  740 ) would lie above the spinal column (inflow tube  710 ) thereby generating downward force to spine (inflow tube  710 ). Therefore, in some embodiments, the positive pressure chambers  750  may lie below the spine  710  to maximize transfer of force to chest wall without placing excess pressure on vertebral connection to tension bars (described below). 
       FIG. 12  shows a top view of a portion of a PXT device  1200 . In the illustrated embodiment, the lower segment include a series of chamber rows, each row having two positive pressure percussion chambers  1250 . In addition, the apex segment  1235  also includes a percussion chamber  1237 . 
     As noted above, the ability to lift the chest wall of a patient may be considered the primary function of the PXT device  700 . Once desired expansion of lung volume, or Functional Residual Capacity (FRC) is achieved, the operator may then initiate percussion therapy in order to dislodge any mucous plugs or the like that may potentially be the cause of an obstruction in the patient&#39;s airways. 
     Exemplary percussion chambers are shown in  FIGS. 13 and 14 . Each positive pressure or percussion chambers  750  may include an interior membrane or shell  1352  connected to a percussive diaphragm  1310  via one or more tension springs  1320 . In a resting position, the percussive diaphragm is recessed from the membrane  730  to allow for chest expansion by the negative pressures. By directly fastening and lifting membrane/chest wall, both the tension springs  1320  and the negative force may work in unison for full chest expansion. 
     At peak FRC or inspiration, one might better simulate a cough reflex by applying percussion as well as downward movement of ribcage by the operator. This may be achieved by increasing the positive pressure in the chambers  1350  until the pressure reaches a point to overcome the force of the tension spring  1320 , causing a pop-off of the percussive diaphragm  1310 , which percusses the chest wall of the patient. Once pop-off occurs, the diaphragm  1310  may reset to its resting, recessed position. 
     The pop-off of the percussive diaphragm  1310  may cause enough gas to be released to possibly disrupt the negative pressure fields of the negative pressure chambers  740 . In some embodiments, in order to alleviate these concerns and/or isolate the negative pressure in the chambers  740  from the positive pressure chambers  1350 , the positive pressure chambers  1350  may be vented/open to ambient air to allow for air to escape, as described below 
     As illustrated in  FIG. 14 , a percussion chamber  1450  may also include a tension bars  1470  and one or more support members  1460 . The tension bars  1470  may lie superior to percussion chamber  1450 . By elevating the tension bars  1470 , it may be possible for an operator to set the resting position of the percussive diaphragms  1410  to allow for more or less chest expansion or more or less percussion. For example, the support members  1460  may be pleats to guide folding of chamber wall like an accordion or bellows. 
     As noted above, each chamber  1450  may be diamond-shaped in order to accommodate flexion during the tail wagging motion. This shape may allow the tail percussion chambers  1450  to move laterally both left and right relative to the divider block  780 . The diamond shape may allow for better contour, rather than wider chambers  1450  that may restrict lateral movement. The percussion chambers  1450  may abut each other on either left or right lateral to divider block, or they may be physically separate. Lateral flexion may allow, for example, for targeting the bend of the left lung compared to the bend of the right lung. The space and volume lost when moving lateral may be lost in the vacuum chambers (VC), without sacrificing percussion surface area. The negative pressure chambers  640  may still be able to suction when compressed due to a rigid plastic stent that coats/lines the internal surface of the long membrane tubules, which interface with negative pressure ribs  740 . 
     In some embodiments, the percussion chambers  1450  may be made of non-elastic rubber that does not distend (stretch) but instead may have pleats to allow for compression in desired positions in order to provide greater lift to the chest wall. Other materials also may be used. These pleats may allow for folding much like an accordion provides the creases that may allow for greater chest expansion by allowing the percussion diaphragms  1410  to become more recessed relative to chest wall thereby expanding Functional Residual Capacity (FRC) in the lungs. 
     The percussion chamber may be supported by a shell  1450  that is exceptional and separate from the outer shell  720  of the negative chambers  740 . With the negative chamber ending at each diaphragm  1410 , excess gas emitted during pop-off to vent out without interrupting/affecting the negative pressure seal in effect to chest wall. If positive pressure is not active with positive pressure chambers open to ambient air pressure, the positive pressure chambers above the diaphragms may be collapsed by increasing the tension in a control set of tension springs  1460 , thereby raising/recessing the percussion chambers  1450  allowing for greater chest expansion. In the illustrated embodiment, the percussion rim  1412  may be raised or lowered to adjust the depth at with percussion chamber membrane diaphragm  1410  rests, with the desired tension at which pop-off occurs controlled by the tension in tension springs  1422   a - b  in conjunction with the specific psi gas sources  105 . The height/depth of the control tension springs  1460  and the pop-off setting established by the tension springs  1422   a - b  may be adjusted manually or electronically, such as by electric motors coupled to the springs. Other mechanisms for establishing the height/depth of the percussion chamber  1450 , the pressure required for pop-off, and/or controlling either feature may be used. The percussion chambers  1450  also may include ridges that define a channel between the negative pressure chambers and the positive pressure chambers. These channels may allow for the escape of air during pop-off. 
     There may be a variety of factors that determine the rate and/or force of the percussion applied by a PXT device  700 . These factors include, for example, the psi of the source gas, the volume of the percussion chamber  1350  with diaphragm in closed (sealed) position, the amount of tension in the springs  1320  holding the diaphragm  1310  in place, and the control and distribution of gas to specific chambers  1350 . Each of these exemplary factors is now explored. 
     The psi of the gas source may be adjusted to deliver any preferred psi less than about fifty PSI by using a gas regulator. Titration of the PSI may allow the health care provider to control the force that the percussion diaphragm  1310  exerts at pop-off, thereby transferring said force to chest wall. For example, less PSI with less tension in a smaller percussion chamber  1350  may deliver less force, which may be desirable, for example, for percussing a neonate&#39;s chest. For a larger patient, such as an adult patient, a higher PSI and/or higher tension in the springs  1320 . In addition, the flow rate may be controlled more precisely using a flowmeter. Use of a flowmeter may allow the source gas to be administered in liters per minute or the like which could more accurately control the smaller volumes and pressures used in, for example, a premature baby, with smaller force transferred to patient. 
     The volume and/or the size of percussion chamber may correspond with the size of the patient. For example, as the neonate size is the smallest, the force of percussion may also be the least. 
     The tension springs  1520  may control the rate of pop-off/percussion. In the embodiment illustrated in  FIG. 15 , multiple tension springs  1520   a  and  1520   b  may be used for each chamber  1550  allowing for multiple percussions from one chamber. Recesses or cuts may be made at rim  1512  of percussion chamber  1550  to allowing for multiple percussion diaphragms to be computer controlled electronically. 
     In some embodiments, the tension springs  1420  may have a counter-force mechanism, essentially a bar  1470  that will begin a superior position relative to the spinal column that may be connected to and receive structural support from the positive pressure vertebrae. This positioning of the tension bar  1470  at an equal or higher position than the ribcage apexes will allow for the percussion diaphragm  1410 , when desired, to be lifted away from chest wall, allowing for greater lung expansion and recruitment of atelectatic lung segments. 
     The distribution of precise gas pressures to individual selected chambers may be achieved through the spine. As noted above, the spine  710  may be honeycombed, allowing multiple pressure tubules within spine to be dedicated to a specific chamber. In some embodiment, a software program may be used to control psi delivered to each chamber  1350  and/or to adjust the tension in individual tension springs  1320  or the position of a percussive diaphragm via the support members  1360 . This may allow for subdivision of the chambers  1350 , in order to vary the percussion patterns i.e., a massage device. For example, percussion may be applied in various wave patterns or the like. 
     As noted above, various modes of operation may be provided. For example, a cough-assist mode may be provided. In a cough assist mode of operation, chest expansion may be facilitated by generating increasingly negative pressures while a percussion chamber is raised to a recessed position. This mode of operation may mimic a deep sigh breath in chest wall. Upon switching from inspiratory phase to expiratory phase, percussion may be applied and/or negative pressure may be disengaged to push/percuss chest wall, thereby “coughing” the patient chest wall. 
     Optionally, the inspiratory:expiratory ratio (I:E ratio) described in the previous paragraph may be synchronized to a positive pressure ventilator attached to patients airway. Synchronization of the PXT device may aide and contribute to more effective lung and airway recruitment for patients with lung collapse. Because the operator is not relying solely on positive pressure via mechanical ventilation, but instead combining the two forms of airway expansion, the provider may resolve the collapsed lung more effectively. 
     Another mode of operation that may be particularly useful for treating spontaneously breathing patients may involve percussion started in the lower airways (i.e. at tail end of PXT) and may be propulsed in an upward manner, thereby stimulating a cough reflex first in lower/smaller airways and then transferred moved in an upward direction out to larger airways. This wave pattern may be highly effective, for example, for airway clearance of cystic fibrosis patients. 
     Referring to  FIGS. 15 a  and 15 b   , another exemplary PXT device  1500  in which only a negative pressure field is generated by the device  1500  is shown in an exploded view and a perspective view, respectively. The device  1500  may include a main body  1502  having an outflow channel  1504  connected to an outflow tube  1580  that may be attached a negative pressure source. The device  1500  also may include a negative pressure shell  1520  coupled to the device  1500  by an adaptor  1530  for coupling the shell  1530  to the body  1520 . The adaptor  1530  may include apertures  1532   a  and  1532   b  to allow the passage of air through the shell  1520  and into the outflow tube  1580 . In operation, when the shell  1520  is coupled to the negative pressure source and applied to a patient, a localized negative pressure field is formed within the shell  1520 . As such, the care provider may be able to target specific lung sections affected by various conditions such as airway collapses, atelectasis, pneumonia, and the like. 
     In addition, the device  1500  also may include a motor  1550  that generates vibrational forces, percussive forces, or both. The forces may be transferred to the patient through shell  1520  to assist in dislodgement of mucus, stimulate a cough reflex, and the like, as described above. The device  1500  also may include a manometer  1540  to measure the pressure of the negative pressure field. 
     Optionally, the device  1500  may include a handle  1560 . The handle  1560  may be grabbed by an operator may during application of the negative pressure field to the patient to physically move/manipulate the patient&#39;s chest during PXT therapy. This upward lift of chest may create a negative airway/alveolar pressure in underlying targeted airways allowing air to pass around mucous plugs, thereby increasing the functional residual capacity of collapsed and/or atelectatic bronchial tree and alveoli. At maximum inspiration or FRC, a downward thrust may be provided by the care provider to force a cough mechanism, thereby dislodging any mucous plugs or the like. At full FRC, secretions may be allowed to drain from smaller to larger airways to eventually removed either by spontaneous or forced cough achieved from downward movement of chest wall by caregiver. By engaging and attaching to the chest wall through suction, the caregiver may synchronize with a patient&#39;s breathing pattern and/or amplify the natural cough mechanism by forcing a larger tidal volume to be inspired by the patient. 
     As opposed to the prior art cuirass that occupies the entire chest and abdominal region of a patient, prohibiting timely access to the patient&#39;s chest wall (which can be a matter of life and death in critical care situations), PXT devices such as device  1500  allow a care provider to administer a localized negative pressure field to specific targeted areas of the chest wall. This can be accomplished even after closing a chest after cardiac surgery without monopolizing the entire thorax of post-operative patient. PXT allows for brief effective therapeutic treatment using localized negative pressure therapy to compensate for and perform the work of the impaired respiratory musculature in order to expand lung fields and mobile secretions at the care provider&#39;s discretion. Rather than asking a patient to cough, PXT allows the care provider to force a cough in the spontaneously breathing patient, or in the unresponsive, sedated, or even paralyzed patient by taking over the work of the respiratory musculature. 
     By generating a negative pressure in distal alveoli/airways affected by mucous plugs, the care provider, for the first time, may draw gas around mucous plug/occluded airway, increasing the functional residual capacity in specific bronchial trees, which facilitates and strengthens the patient&#39;s own cough reflex. 
     In some embodiments, the device  1500  may include an activation button  1572  that enables an operator to selectively generate a negative pressure field inside the shell  1520 . This may be accomplished, for example, by introducing ambient air into the outflow channel  1504  before the shell  1520 , as described below in connection with  FIGS. 16 a  and 16 b   . As a result, shell  1520  is operatively coupled/de-coupled from the negative pressure source, which may be, for example, the airflow devices and/or portable suction devices described above. 
     The shell  1520  may be made of any material that may allow for sufficient negative pressure to be generated in the shell  1520 , such as plastic or the like. Preferably, the shell  1520  is semi-rigid to allow some flexion to occur to accommodate variations in patient anatomy. The various sized and shaped shells  1520  may be used to correspond and/or mimic the different sizes and shapes of a patient&#39;s anatomy, such as the size and shape of a patient&#39;s lung and/or chest. For example, the shell  1520  may be sized in accordance with the various sizes described above with respect to other embodiments. In some embodiments, the shell  1520  may be substantially triangular. 
     In some embodiments, shell  1520  may be an anesthetic mask. In such embodiments, adaptor  1530  may be a 15 millimeter and/or a 22 millimeter adaptor to receive 15 millimeter and 22 millimeter sized anesthetic masks. In this manner, different sized shells may be interchangeably attachable to the device  1500 . For example, masks may be size 0 mask, size 1 masks, size 2 masks, size 3 masks, size 4 masks, size 5 masks, or size 6 masks to accommodate different sized patients. Other methods of interchangeability also may be used. Exemplary anesthetic masks includes those made by Becton, Dickinson and Company of Franklin Lakes, N.J., those made by AliMed, Inc. of Dedham, Mass., those made by InterSurgical Ltd. of East Syracuse, N.Y., and the like. Other shells and masks also may be used. 
     The motor  1550  may generate a force that is either a vibrational force, a percussive force, or both. The force may then be applied to a patient via the shell  1520 , which is operatively coupled to the motor  1550  via the relief valve  1530 . In some embodiments, percussive force through shell  1520  may be applied during an expiratory/downward movement of chest wall in order to dislodge mucous plugs in underlying airways, for example. Alternatively, or additionally, percussive force may be applied during an upward/inhalation movement. Percussive force may be especially useful for larger patients, such as adults. Similarly, vibrational force also may be applied through the shell  1520  during an expiratory/downward movement, an upward/inhalation movement, or both. Vibrational force may be especially useful for smaller patients, such as pediatric and neo-natal patients. 
     Exemplary vibratory and/or percussive motors include motors found in handheld massage units, such as neck/back massagers. Exemplary massage units include the HOMEDICS Therapist Select® Compact Percussion Massager sold by HOMEDICS of Commerce Township, MI, the WAHL Professional Massager #4120-1701 and WAHL 4290-300 Deep Tissue Percussion Massager both of which are sold by Wahl Clipper Corporation of Sterling, IL, the Pure-Wave CM7 Cordless Massager sold by Pado of Valencia, Calif. and the FLEXXSONIC Therapeutic Massager sold by Flexxsonic Corporation of Mount Prospect, IL. Other motors also may be used. 
     Referring to  FIGS. 16 a  and 16 b   , functional diagrams of another exemplary PXT device in a first operational mode and a second operational mode are shown. Like the device shown in  FIGS. 15 a  and 15 b   , the device of  FIGS. 16 a  and 16 b    only generates a negative pressure field. The device  1600  may generally operate as the device described in  FIGS. 15 a  and 15 b   . Device  1600  have include main body  1602  having an outflow channel  1604  connected to an outflow tube  1680  that may be attached a negative pressure source. The device  1600  also may include a negative pressure shell (not shown) that operates as shell  1520  described above and is coupled to the device  1600  by an adaptor  1630  that includes apertures  1632   a  and  1632   b  to allow the passage of air through the shell and into the outflow tube  1680 . The device also may include a motor  1650  for generating a force (percussive, vibratory, or both) that may be applied to the patient via the shell. 
     The device  1600  may include an activation mechanism  1672  that may allow the operator to activate/de-active the negative pressure field in the shell. For example, the activation mechanism  1672  may be movable between a first position in which ambient air is introduced into the outflow channel to interrupt negative gas flow into the shell and a second position in which the negative pressure field is generated within the shell via negative gas flow. As shown in  FIG. 16 a   , the activation mechanism  1672  may be a spring loaded button that, when in the first position shown, allows ambient air to enter the channel  1604 . Accordingly, a negative pressure field is not generated in the shell. When the activation mechanism is moved to the second position, as shown in  FIG. 16 b   , the channel  1604  is closed, negative gas flow is applied to the shell and a negative pressure field is generated therein. 
     The shell may be selectively couplable to the motor  1650  so that the operator may choose to apply the force to the patient as follows. The adaptor  1630  may be movable between a first position in which the adaptor  1630  is operatively coupled to the motor  1650  to transfer the force to the shell and a second position in which the shell is substantially disengaged from the motor (i.e. no or little force is transferred to the shell). For example, as shown in  FIG. 16 a   , the adaptor  1630  is shown in the second position whereby no forces generated by the motor  1650  are applied to the shell. This may be useful during an inhalation/upward movement of therapy in which the operator applies a negative pressure field to the patient via the shell and lifts the chest wall to simulate an inhalation movement. During a downward/exhalation movement, the operator may press downward onto the patient&#39;s chest, moving the adaptor  1630  to the first position in which force is transferred to the patient. In this manner, a simulated cough reflex can be achieved to dislodge mucus and the like, as described above. During this downward movement, the operator may release the activation mechanism to eliminate the negative pressure field in the shell (as shown in  FIG. 16 a   ), or may maintain the negative pressure field. 
     Optionally, the device may include a locking mechanism to keep the shell operatively coupled to the motor  1650  regardless of the motion of the device  1600 . As shown in  FIGS. 16 c  and 16 d   , the locking mechanism may be a locking pin  1690  that may be inserted into the device  1600  to physically hold the adaptor  1630  in the first (or operative) position. In the illustrated embodiment, the pin  1690  may be slid into the device  1600  and twisted so that a notch  1692  engages the valve  1630 , thereby prohibit disengagement from the motor  1650 . The device  1600  also may include a master switch  1674  that turns the motor  1650  on or off to enable/disable force application entirely. 
     The device  1600   a  also may include a negative pressure relief valve  1700  operatively coupled to the outflow channel  1604 . A detailed view of the exemplary negative pressure relief valve  1700  is shown in  FIG. 17 . The exemplary negative pressure relief valve  1700  may act as a pop-off valve that introduces ambient air into the outflow channel  1604  when pressure in the channel  1604  exceeds a predetermined threshold. Specifically, the negative pressure relief valve  1700  may define a portion of the outflow channel between a seal  1722  and an inlet nozzle  1710 . The inlet nozzle  1710  may closed by a valve seat  1712  kept in place a mechanical force generated by spring  1720  and applied through a seat holder  1714 . The force applied by the spring  1720  may be adjustable by a care provider by turning a cap  1730  coupled to an adjustable screw  1732 . When pressure in the channel  1604  is enough to overcome the force applied by the screw  1720 , the seat holder  1714  and seat  1712  are moved, opening the inlet nozzle  1710  to allow ambient air to enter the channel  1604 . As such, a maximum pressure level can be maintained by the device  1600 . Other methods to regulate the airflow in the channel  1604  also may be used. 
     While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.