Patent Publication Number: US-2022211971-A1

Title: Combined respiratory muscle training and oscillating positive expiratory pressure device

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. Non-Provisional application Ser. No. 16/507,799, filed on Jul. 10, 2019, pending, which is a continuation of U.S. Non-Provisional application Ser. No. 15/223,564, filed on Jul. 29, 2016, now U.S. Pat. No. 10,449,324, which claims the benefit of U.S. Provisional Application No. 62/199,113, filed on Jul. 30, 2015, expired, the entireties of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to respiratory treatment devices, and in particular, to combined respiratory muscle training (“RMT”) and oscillating positive expiratory pressure (“OPEP”) devices. 
     BACKGROUND 
     Each day, humans may produce upwards of 30 milliliters of sputum, which is a type of bronchial secretion. Normally, an effective cough is sufficient to loosen secretions and clear them from the body&#39;s airways. However, for individuals suffering from more significant bronchial obstructions, such as collapsed airways, a single cough may be insufficient to clear the obstructions. 
     OPEP therapy represents an effective bronchial hygiene technique for the removal of bronchial secretions in the human body and is an important aspect in the treatment and continuing care of patients with bronchial obstructions, such as those suffering from chronic obstructive lung disease. It is believed that OPEP therapy, or the oscillation of exhalation pressure at the mouth during exhalation, effectively transmits an oscillating back pressure to the lungs, thereby splitting open obstructed airways and loosening the secretions contributing to bronchial obstructions. The benefits of OPEP therapy include decrease in sputum viscoelasticity, increase in forces disconnecting sputum from airway passages, and increase in sputum expectoration. 
     OPEP therapy is an attractive form of treatment because it can be easily taught to most patients, and such patients can assume responsibility for the administration of OPEP therapy throughout a hospitalization and also from home. To that end, a number of portable OPEP devices have been developed. 
     Like OPEP therapy, RMT has been shown to improve lung hygiene in both healthy individuals and patients with a variety of lung diseases. RMT includes pressure threshold resistance, which requires a user to achieve and maintain a set pressure during inhalation or exhalation, and flow resistance, which restricts the flow of air during inhalation or exhalation. The benefits of RMT include increased respiratory muscle strength, reduced dyspnea (breathlessness), increased exercise performance, and improved quality of life. 
     Like OPEP therapy, RMT is an attractive form of treatment because it can be easily taught to most patients, and such patients can assume responsibility for the administration of RMT therapy throughout a hospitalization and also from home. 
     In this regard, there is a need for a single device that performs both OPEP therapy and RMT, while maintaining the performance of individual devices that deliver only OPEP therapy or only RMT. 
     BRIEF SUMMARY 
     In one aspect, a respiratory treatment device includes a housing enclosing a plurality of chambers, with a first opening in the housing configured to transmit air exhaled into and air inhaled from the housing, a second opening in the housing configured to permit air exhaled into the first opening to exit the housing, and a third opening in the housing configured to permit air outside the housing to enter the housing upon inhalation at the first opening. An exhalation flow path is defined between the first opening and the second opening, and an inhalation flow path is defined between the third opening and the first opening. A restrictor member is positioned in the exhalation flow path and the inhalation flow path and is movable between a closed position, where a flow of air along the exhalation flow path or the inhalation flow path is restricted, and an open position, where the flow of exhaled air along the exhalation flow path or the inhalation flow path is less restricted. A vane is in fluid communication with the exhalation flow path and the inhalation flow path, and is connected to the restrictor member and configured to reciprocate between a first position and a second position in response to a flow of exhaled air along the exhalation flow path or the inhalation flow path. 
     In another aspect, the second opening may include a one-way exhalation valve configured to permit air exhaled into the housing to exit the housing upon exhalation at the first opening. The one-way exhalation valve may be configured to open in response to a positive threshold pressure. The threshold pressure may be selectively adjustable. The one-way exhalation valve may include a spring configured to bias the one-way valve toward a closed position. A level of bias may be selectively adjustable. A cross-sectional area of the second opening may be selectively adjustable to control a resistance to the flow of air therethrough. 
     In another aspect, the third opening may include a one-way inhalation valve configured to permit air outside the housing to enter the housing upon inhalation at the first opening. The one-way inhalation valve may be configured to open in response to a negative threshold pressure. The threshold pressure may be selectively adjustable. The one-way inhalation valve may include a spring configured to bias the one-way valve toward a closed position. A level of bias may be selectively adjustable. A cross-sectional area of the second opening may be selectively adjustable to control a resistance to the flow of air therethrough. 
     In yet another aspect, a one-way valve is positioned along the exhalation flow path between the first opening and the second opening. The one-way valve may be configured to open in response to air exhaled into the first opening, and close in response to air inhaled through the first opening. 
     In another aspect, a one-way valve is positioned along the inhalation flow path between the third opening and the first opening. The one-way valve may be configured to open in response to air inhaled through the first opening, and close in response to air exhaled into the first opening. 
     In another aspect, the restrictor member is positioned in a first chamber of the plurality of chambers, and the vane is positioned in a second chamber of the plurality of chambers. The flow of air through the first chamber is restricted when the restrictor member is in the closed position, and the flow of air through the first chamber is less restricted when the restrictor member is in the open position. The first chamber and the second chamber may be connected by an orifice. The vane is positioned adjacent the orifice and may be configured to move the restrictor member between the closed position and the open position in response to an increased pressure adjacent the vane. 
     In another aspect, the exhalation flow path and the inhalation flow path form an overlapping portion. The flow of air along the exhalation flow path and the inhalation flow path along the overlapping portion may be in the same direction. The restrictor member may be positioned in the overlapping portion, and the vane may be in fluid communication with the overlapping portion. 
     In another aspect, a size of the orifice is configured to increase in response to the flow of exhaled air through the orifice. The orifice may be formed within a variable nozzle. The orifice may be configured to close in response to a negative pressure from the flow of inhaled air along the inhalation flow path. 
     In another aspect, the vane is operatively connected to the restrictor member by a shaft. A face of the restrictor member is rotatable about an axis of rotation. 
     In yet another aspect, a flow resistor for a respiratory device includes a conduit for transmitting a flow of air. The conduit has a cross sectional area. A one-way valve is positioned within the conduit and is configured to open in response to the flow of air in a first direction, and close in response to the flow of air in a second direction. The one-way valve may have a cross-sectional area less than the cross sectional area of the conduit. An adjustment plate is positioned within the conduit forming an open section and a blocking section. The blocking section may have a cross-sectional area less than the cross-sectional area of the conduit. An orientation of the adjustment plate relative to the conduit may be selectively adjustable. The orientation of the open section relative to the cross-sectional area of the one-way valve is selectively adjustable. The adjustment plate may be positioned within the conduit adjacent to the one-way valve. A flow of air in the second direction may be permitted to flow around the one-way valve through the open section. The adjustment plate may be positioned within the conduit adjacent to the one-way valve. The one-way valve may be configured to open in response to inhalation by a user at a first end of the conduit, and close in response to exhalation by a user at the first end of the conduit. 
     In yet another aspect, a flow resistor for a respiratory device includes a housing defining a conduit for the flow of air therethrough, and a one-way valve positioned in the conduit. The one-way valve is configured to open in response to the flow of air through the conduit in a first direction and close in response to the flow of air through the conduit in a second direction. An opening in the conduit permits the flow of air into or out of the conduit. A cross-sectional area of the opening is selectively adjustable. The housing may include a first section and a second section, wherein a position of the first section of the housing relative to a position of the second section of the housing is selectively adjustable. Selective adjustment of the first section relative to the second section adjusts a cross-sectional area of the opening. The one-way valve may be positioned in the first section of the housing. The opening may be positioned in the first section of the housing. 
     In yet another aspect, a pressure threshold resistor includes a housing having a first section and a second section, the first section and the second section defining a conduit for the flow of air therethrough. A one-way valve is positioned in the conduit and is movable between a closed position, where the flow of air through the conduit is blocked, and an open position, where air is permitted to flow through the conduit. A biasing member may be configured to bias the one-way valve toward the closed position. The one-way valve may be configured to move from the closed position to an open position when a pressure in the conduit exceeds a threshold pressure. 
     In another aspect, the biasing member is a spring. A position of the first section of the housing relative to the second section of the housing may be selectively adjustable. Adjustment of the position of the first section of the housing relative to the second section of the housing may adjust the bias on the one-way valve. Adjustment of the position of the first section of the housing relative to the second section of the housing may adjust the threshold pressure. The biasing member may be a spring, and adjustment of the position of the first section of the housing relative to the second section may adjust a compression of the spring. 
     In yet another aspect, a respiratory treatment device includes a housing enclosing at least one chamber, a first opening in the housing configured to transmit air exhaled into and air inhaled from the housing, a second opening in the housing configured to permit air exhaled into the first opening to exit the housing, and a third opening in the housing configured to permit air outside the housing to enter the housing upon inhalation at the first opening. An exhalation flow path is defined between the first opening and the second opening, and an inhalation flow path defined between the third opening and the first opening. A restrictor member is positioned in the exhalation flow path and is movable between a closed position, where a flow of air along the exhalation flow path or is restricted, and an open position, where the flow of exhaled air along the exhalation flow path is less restricted. 
     In another aspect, a vane is in fluid communication with the exhalation flow path, is operatively connected to the restrictor member, and is configured to reciprocate between a first position and a second position in response to a flow of exhaled air along the exhalation flow path. The restrictor member may not be positioned in the inhalation flow path. 
     In another aspect, the third opening comprises a one-way inhalation valve configured to permit air outside the housing to enter the housing upon inhalation at the first opening. The one-way inhalation valve may be configured to open in response to a negative threshold pressure. The threshold pressure may be selectively adjustable. The one-way inhalation valve may include a spring configured to bias the one-way valve toward a closed position. The level of bias may be selectively adjustable. A cross-sectional area of the third opening may be selectively adjustable to control a resistance to the flow of air therethrough. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an OPEP device; 
         FIG. 2  is a rear perspective view of the OPEP device of  FIG. 1 ; 
         FIG. 3  is a cross-sectional perspective view taken along line III in  FIG. 1  of the OPEP device shown without the internal components of the OPEP device; 
         FIG. 4  is an exploded view of the OPEP device of  FIG. 1 , shown with the internal components of the OPEP device; 
         FIG. 5  is a cross-sectional perspective view taken along line III in  FIG. 1  of the OPEP device shown with the internal components of the OPEP device; 
         FIG. 6  is a different cross-sectional perspective view taken along line VI in  FIG. 1  of the OPEP device shown with the internal components of the OPEP device; 
         FIG. 7  is a different cross-sectional perspective view taken along line VII in  FIG. 1  of the OPEP device shown with the internal components of the OPEP device; 
         FIG. 8  is a front perspective view of a restrictor member operatively connected to a vane; 
         FIG. 9  is a rear perspective view of the restrictor member operatively connected to the vane shown in  FIG. 8 ; 
         FIG. 10  is a front view of the restrictor member operatively connected to the vane shown in  FIG. 8 ; 
         FIG. 11  is a top view of the restrictor member operatively connected to the vane shown in  FIG. 8 ; 
         FIG. 12  is a front perspective view of a variable nozzle shown without the flow of exhaled air therethrough; 
         FIG. 13  is a rear perspective view of the variable nozzle of  FIG. 12  shown without the flow of exhaled air therethrough; 
         FIG. 14  is a front perspective view of the variable nozzle of  FIG. 12  shown with a high flow of exhaled air therethrough; 
         FIGS. 15A-C  are top phantom views of the OPEP device of  FIG. 1  showing an exemplary illustration of the operation of the OPEP device of  FIG. 1 ; 
         FIG. 16  is a front perspective view of a different embodiment of a variable nozzle shown without the flow of exhaled air therethrough; 
         FIG. 17  is a rear perspective view of the variable nozzle of  FIG. 16  shown without the flow of exhaled air therethrough; 
         FIG. 18  is a front perspective view of a second embodiment of an OPEP device; 
         FIG. 19  is a rear perspective view of the OPEP device of  FIG. 18 ; 
         FIG. 20  is an exploded view of the OPEP device of  FIG. 18 , shown with the internal components of the OPEP device; 
         FIG. 21  is a cross-sectional view taken along line I in  FIG. 18  of the OPEP device, shown with the internal components of the OPEP device; 
         FIG. 22  is a cross-sectional view taken along line II in  FIG. 18  of the OPEP device, shown with the internal components of the OPEP device; 
         FIG. 23  is a cross-sectional view taken along line III in  FIG. 18  of the OPEP device, shown with the internal components of the OPEP device; 
         FIG. 24  is a front perspective view of an adjustment mechanism of the OPEP device of  FIG. 18 ; 
         FIG. 25  is a rear perspective view of the adjustment mechanism of  FIG. 24 ; 
         FIG. 26  is a front perspective view of a restrictor member operatively connected to a vane for use in the OPEP device of  FIG. 18 ; 
         FIG. 27  is a front perspective view of the adjustment mechanism of  FIG. 24  assembled with the restrictor member and the vane of  FIG. 26 ; 
         FIG. 28  is a partial cross-sectional view of the assembly of  FIG. 27  within the OPEP device of  FIG. 18 ; 
         FIGS. 29A-B  are partial cross-sectional views illustrating installation of the assembly of  FIG. 27  within the OPEP device of  FIG. 18 ; 
         FIG. 30  is a front view of the OPEP device of  FIG. 18  illustrating an aspect of the adjustability of the OPEP device; 
         FIG. 31  is a partial cross-sectional view of the assembly of  FIG. 27  within the OPEP device of  FIG. 18 ; 
         FIGS. 32A-B  are partial cross-sectional views taken along line III in  FIG. 18  of the OPEP device, illustrating possible configurations of the OPEP device; 
         FIGS. 33A-B  are top phantom views illustrating the adjustability of the OPEP device of  FIG. 18 ; 
         FIGS. 34A-B  are top phantom views of the OPEP device of  FIG. 18 , illustrating the adjustability of the OPEP device; 
         FIG. 35  is a front perspective view of another embodiment of an OPEP device; 
         FIG. 36  is a rear perspective view of the OPEP device of  FIG. 35 ; 
         FIG. 37  is a perspective view of the bottom of the OPEP device of  FIG. 35 ; 
         FIG. 38  is an exploded view of the OPEP device of  FIG. 35 ; 
         FIG. 39  is a cross-sectional view taken along line I in  FIG. 35 , shown without the internal components of the OPEP device; 
         FIG. 40  is a cross-sectional view taken along line I in  FIG. 35 , shown with the internal components of the OPEP device; 
         FIG. 41  is a front-perspective view of an inner casing of the OPEP device of  FIG. 35 ; 
         FIG. 42  is a cross-sectional view of the inner casing taken along line I of in  FIG. 41 ; 
         FIG. 43  is a perspective view of a vane of the OPEP device of  FIG. 35 ; 
         FIG. 44  is a front perspective view of a restrictor member of the OPEP device of  FIG. 35 ; 
         FIG. 45  is a rear perspective view of the restrictor member of the  FIG. 44 ; 
         FIG. 46  is a front view of the restrictor member of  FIG. 44 ; 
         FIG. 47  is a front perspective view of an adjustment mechanism of the OPEP device of  FIG. 35 ; 
         FIG. 48  is a rear perspective view of the adjustment mechanism of  FIG. 47 ; 
         FIG. 49  is a front perspective view of the adjustment mechanism of  FIGS. 47-48  assembled with the restrictor member of  FIGS. 44-46  and the vane of  FIG. 43 ; 
         FIG. 50  is a front perspective view of a variable nozzle of the OPEP device of  FIG. 35 ; 
         FIG. 51  is a rear perspective view of the variable nozzle of  FIG. 50 ; 
         FIG. 52  is a front perspective view of the one-way valve of the OPEP device of  FIG. 35 ; 
         FIG. 52  is a front perspective view of the one-way valve of the OPEP device of  FIG. 35 . 
         FIG. 53  is a perspective view of another embodiment of a respiratory treatment device; 
         FIG. 54  is an exploded view of the respiratory treatment device of  FIG. 53 ; 
         FIG. 55  is a cross-sectional perspective view taken along line I in  FIG. 53  of the respiratory treatment device shown with the internal components of the device; 
         FIG. 56  is a cross-sectional perspective view taken along line II in  FIG. 53  of the respiratory treatment device shown with the internal components of the device; 
         FIG. 57  is a different cross-sectional perspective view taken along line I in  FIG. 53  of the respiratory treatment device, showing a portion of an exemplary exhalation flow path; 
         FIG. 58  is a different cross-sectional perspective view taken along line II in  FIG. 53 , showing a portion of an exemplary exhalation flow path; 
         FIG. 59  is another cross-sectional perspective view taken along line I in  FIG. 53 , showing a portion of an exemplary inhalation flow path; 
         FIG. 60  is another cross-sectional perspective view taken along line II in  FIG. 53 , showing a portion of an exemplary inhalation flow path; 
         FIGS. 61A-E  includes perspective, side, top, cross-sectional, and exploded views of a pressure threshold resistor; 
         FIGS. 62A-B  are side views of the pressure threshold resistor of  FIGS. 61A-E , illustrating the adjustability of the threshold pressure required to open the valve of the pressure threshold resistor; 
         FIGS. 63A-B  are cross-sectional views of the pressure threshold resistor of  FIGS. 61A-E , illustrating the adjustability of the threshold pressure required to open the valve of the pressure threshold resistor; 
         FIGS. 64A-D  are side, perspective, and partial cross-sectional views of the pressure threshold resistor of  FIGS. 61A-E  connected to the OPEP device of  FIG. 35 ; 
         FIGS. 65A-B  are side and perspective views of the pressure threshold resistor of  FIGS. 61A-E  connected to another commercially available OPEP device; 
         FIGS. 66A-E  are side and cross-sectional views of another pressure threshold resistor; 
         FIGS. 67A-B  are side views of the pressure threshold resistor of  FIGS. 66A-E  illustrating the adjustability of the threshold pressure required to open the valve of the pressure threshold resistor; 
         FIGS. 68A-B  are cross-sectional views of the pressure threshold resistor of  FIGS. 66A-E  illustrating the adjustability of the threshold pressure required to open the valve of the pressure threshold resistor; 
         FIGS. 69A-E  are perspective and cross-sectional views of a flow resistor; 
         FIGS. 70A-C  are perspective, cross-sectional, and front views of another flow resistor; 
         FIG. 71  is a side view of the flow resistor of  FIGS. 70A-C  connected to the OPEP device of  FIG. 35 ; 
         FIGS. 72A-C  are perspective, front, and side views of a combined RMT and OPEP device; 
         FIGS. 73A-F  are full and partial cross-sectional views of the combined RMT and OPEP device of  FIGS. 72A-C , illustrating administration of RMT and OPEP therapy upon exhalation; and, 
         FIGS. 74A-E  are full and partial cross-sectional views of the combined RMT and OPEP device of  FIGS. 72A-C , illustrating administration of RMT and OPEP therapy upon inhalation. 
     
    
    
     DETAILED DESCRIPTION 
     OPEP Therapy 
     OPEP therapy is effective within a range of operating conditions. For example, an adult human may have an exhalation flow rate ranging from 10 to 60 liters per minute, and may maintain a static exhalation pressure in the range of 8 to 18 cm H 2 O. Within these parameters, OPEP therapy is believed to be most effective when changes in the exhalation pressure (i.e., the amplitude) range from 5 to 20 cm H 2 O oscillating at a frequency of 10 to 40 Hz. In contrast, an adolescent may have a much lower exhalation flow rate, and may maintain a lower static exhalation pressure, thereby altering the operating conditions most effective for the administration of OPEP therapy. Likewise, the ideal operating conditions for someone suffering from a respiratory illness, or in contrast, a healthy athlete, may differ from those of an average adult. As described below, the components of the disclosed OPEP devices are selectable and/or adjustable so that ideal operating conditions (e.g., amplitude and frequency of oscillating pressure) may be identified and maintained. Each of the various embodiments described herein achieve frequency and amplitude ranges that fall within the desired ranges set forth above. Each of the various embodiments described herein may also be configured to achieve frequencies and amplitudes that fall outside the ranges set forth above. 
     First OPEP Embodiment 
     Referring first to  FIGS. 1-4 , a front perspective view, a rear perspective view, a cross-sectional front perspective view, and an exploded view of an OPEP device  100  are shown. For purposes of illustration, the internal components of the OPEP device  100  are omitted in  FIG. 3 . The OPEP device  100  generally comprises a housing  102 , a chamber inlet  104 , a first chamber outlet  106 , a second chamber outlet  108  (best seen in  FIGS. 2 and 7 ), and a mouthpiece  109  in fluid communication with the chamber inlet  104 . While the mouthpiece  109  is shown in  FIGS. 1-4  as being integrally formed with the housing  102 , it is envisioned that the mouthpiece  109  may be removable and replaceable with a mouthpiece  109  of a different size or shape, as required to maintain ideal operating conditions. In general, the housing  102  and the mouthpiece  109  may be constructed of any durable material, such as a polymer. One such material is Polypropylene. Alternatively, acrylonitrile butadiene styrene (ABS) may be used. 
     Alternatively, other or additional interfaces, such as breathing tubes or gas masks (not shown) may be attached in fluid communication with the mouthpiece  109  and/or associated with the housing  102 . For example, the housing  102  may include an inhalation port (not shown) having a separate one-way inhalation valve (not shown) in fluid communication with the mouthpiece  109  to permit a user of the OPEP device  100  both to inhale the surrounding air through the one-way valve, and to exhale through the chamber inlet  104  without withdrawing the mouthpiece  109  of the OPEP device  100  between periods of inhalation and exhalation. In addition, any number of aerosol delivery devices may be connected to the OPEP device  100 , for example, through the inhalation port mentioned above, for the simultaneous administration of aerosol and OPEP therapies. As such, the inhalation port may include, for example, an elastomeric adapter, or other flexible adapter, capable of accommodating the different mouthpieces or outlets of the particular aerosol delivery device that a user intends to use with the OPEP device  100 . As used herein, the term aerosol delivery devices should be understood to include, for example, without limitation, any nebulizer, soft mist inhaler, pressurized metered dose inhaler, dry powder inhaler, combination of a holding chamber a pressurized metered dose inhaler, or the like. Suitable commercially available aerosol delivery devices include, without limitation, the AEROECLIPSE nebulizer, RESPIMAT soft mist inhaler, LC Sprint nebulizer, AEROCHAMBER PLUS holding chambers, MICRO MIST nebulizer, SIDESTREAM nebulizers, Inspiration Elite nebulizers, FLOVENT pMDI, VENTOLIN pMDI, AZMACORT pMDI, BECLOVENT pMDI, QVAR pMDI and AEROBID PMDI, XOPENEX pMDI, PROAIR pMDI, PROVENT pMDI, SYMBICORT pMDI, TURBOHALER DPI, and DISKHALER DPI. Descriptions of suitable aerosol delivery devices may be found in U.S. Pat. Nos. 4,566,452; 5,012,803; 5,012,804; 5,312,046; 5,497,944; 5,622,162; 5,823,179; 6,293,279; 6,435,177; 6,484,717; 6,848,443; 7,360,537; 7,568,480; and, 7,905,228, the entireties of which are herein incorporated by reference. 
     In  FIGS. 1-4 , the housing  102  is generally box-shaped. However, a housing  102  of any shape may be used. Furthermore, the chamber inlet  104 , the first chamber outlet  106 , and the second chamber outlet  108  could be any shape or series of shapes, such as a plurality (i.e., more than one) of circular passages or linear slots. More importantly, it should be appreciated that the cross-sectional area of the chamber inlet  104 , the first chamber outlet  106 , and the second chamber outlet  108  are only a few of the factors influencing the ideal operating conditions described above. 
     Preferably, the housing  102  is openable so that the components contained therein can be periodically accessed, cleaned, replaced, or reconfigured, as required to maintain the ideal operating conditions. As such, the housing  102  is shown in  FIGS. 1-4  as comprising a front section  101 , a middle section  103 , and a rear section  105 . The front section  101 , the middle section  103 , and the rear section  105  may be removably connected to one another by any suitable means, such as a snap-fit, a compression fit, etc., such that a seal forms between the relative sections sufficient to permit the OPEP device  100  to properly administer OPEP therapy. 
     As shown in  FIG. 3 , an exhalation flow path  110 , identified by a dashed line, is defined between the mouthpiece  109  and at least one of the first chamber outlet  106  and the second chamber outlet  108  (best seen in  FIG. 7 ). More specifically, the exhalation flow path  110  begins at the mouthpiece  109 , passes through the chamber inlet  104 , and enters into a first chamber  114 , or an entry chamber. In the first chamber  114 , the exhalation flow path makes a 180-degree turn, passes through a chamber passage  116 , and enters into a second chamber  118 , or an exit chamber. In the second chamber  118 , the exhalation flow path  110  may exit the OPEP device  100  through at least one of the first chamber outlet  106  and the second chamber outlet  108 . In this way, the exhalation flow path  110  is “folded” upon itself, i.e., it reverses longitudinal directions between the chamber inlet  104  and one of the first chamber outlet  106  or the second chamber outlet  108 . However, those skilled in the art will appreciate that the exhalation flow path  110  identified by the dashed line is exemplary, and that air exhaled into the OPEP device  100  may flow in any number of directions or paths as it traverses from the mouthpiece  109  or chamber inlet  104  and the first chamber outlet  106  or the second chamber outlet  108 . 
       FIG. 3  also shows various other features of the OPEP device  100  associated with the housing  102 . For example, a stop  122  prevents a restrictor member  130  (see  FIG. 5 ), described below, from opening in a wrong direction; a seat  124  shaped to accommodate the restrictor member  130  is formed about the chamber inlet  104 ; and, an upper bearing  126  and a lower bearing  128  are formed within the housing  102  and configured to accommodate a shaft rotatably mounted therebetween. One or more guide walls  120  are positioned in the second chamber  118  to direct exhaled air along the exhalation flow path  110 . 
     Turning to  FIGS. 5-7 , various cross-sectional perspective views of the OPEP device  100  are shown with its internal components. The internal components of the OPEP device  100  comprise a restrictor member  130 , a vane  132 , and an optional variable nozzle  136 . As shown, the restrictor member  130  and the vane  132  are operatively connected by means of a shaft  134  rotatably mounted between the upper bearing  126  and the lower bearing  128 , such that the restrictor member  130  and the vane  132  are rotatable in unison about the shaft  134 . As described below in further detail, the variable nozzle  136  includes an orifice  138  configured to increase in size in response to the flow of exhaled air therethrough. 
       FIGS. 4-6  further illustrate the division of the first chamber  114  and the second chamber  118  within the housing  102 . As previously described, the chamber inlet  104  defines an entrance to the first chamber  114 . The restrictor member  130  is positioned in the first chamber  114  relative to a seat  124  about the chamber inlet  104  such that it is moveable between a closed position, where a flow of exhaled air along the exhalation flow path  110  through the chamber inlet  104  is restricted, and an open position, where the flow of exhaled air through the chamber inlet  104  is less restricted. Likewise, the variable nozzle  136 , which is optional, is mounted about or positioned in the chamber passage  116 , such that the flow of exhaled air entering the first chamber  114  exits the first chamber  114  through the orifice  138  of the variable nozzle  136 . Exhaled air exiting the first chamber  114  through the orifice  138  of the variable nozzle  136  enters the second chamber, which is defined by the space within the housing  102  occupied by the vane  132  and the guide walls  120 . Depending on the position of the vane  132 , the exhaled air is then able to exit the second chamber  118  through at least one of the first chamber outlet  106  and the second chamber outlet  108 . 
       FIGS. 8-14  show the internal components of the OPEP device  100  in greater detail. Turning first to  FIGS. 8-9 , a front perspective view and a rear perspective view shows the restrictor member  130  operatively connected to the vane  132  by the shaft  134 . As such, the restrictor member  130  and the vane  132  are rotatable about the shaft  134  such that rotation of the restrictor member  130  results in a corresponding rotation of the vane  132 , and vice-versa. Like the housing  102 , the restrictor member  130  and the vane  132  may be made of constructed of any durable material, such as a polymer. Preferably, they are constructed of a low shrink, low friction plastic. One such material is acetal. 
     As shown, the restrictor member  130 , the vane  132 , and the shaft  134  are formed as a unitary component. The restrictor member  130  is generally disk-shaped, and the vane  132  is planar. The restrictor member  130  includes a generally circular face  140  axially offset from the shaft  134  and a beveled or chamfered edge  142  shaped to engage the seat  124  formed about the chamber inlet  104 . In this way, the restrictor member  130  is adapted to move relative to the chamber inlet  104  about an axis of rotation defined by the shaft  134  such that the restrictor member  130  may engage the seat  124  in a closed position to substantially seal and restrict the flow of exhaled air through the chamber inlet  104 . However, it is envisioned that the restrictor member  130  and the vane  132  may be formed as separate components connectable by any suitable means such that they remain independently replaceable with a restrictor member  130  or a vane  132  of a different shape, size, or weight, as selected to maintain ideal operating conditions. For example, the restrictor member  130  and/or the vane  132  may include one or more contoured surfaces. Alternatively, the restrictor member  130  may be configured as a butterfly valve. 
     Turning to  FIG. 10 , a front view of the restrictor member  130  and the vane  132  is shown. As previously described, the restrictor member  130  comprises a generally circular face  140  axially offset from the shaft  134 . The restrictor member  130  further comprises a second offset designed to facilitate movement of the restrictor member  130  between a closed position and an open position. More specifically, a center  144  of the face  140  of the restrictor member  130  is offset from the plane defined by the radial offset and the shaft  134 , or the axis of rotation. In other words, a greater surface area of the face  140  of the restrictor member  130  is positioned on one side of the shaft  134  than on the other side of the shaft  134 . Pressure at the chamber inlet  104  derived from exhaled air produces a force acting on the face  140  of the restrictor member  130 . Because the center  144  of the face  140  of the restrictor member  130  is offset as described above, a resulting force differential creates a torque about the shaft  134 . As further explained below, this torque facilitates movement of the restrictor member  130  between a closed position and an open position. 
     Turning to  FIG. 11 , a top view of the restrictor member  130  and the vane  132  is shown. As illustrated, the vane  132  is connected to the shaft  134  at a 75° angle relative to the face  140  of restrictor member  130 . Preferably, the angle will remain between 60° and 80°, although it is envisioned that the angle of the vane  132  may be selectively adjusted to maintain the ideal operating conditions, as previously discussed. It is also preferable that the vane  132  and the restrictor member  130  are configured such that when the OPEP device  100  is fully assembled, the angle between a centerline of the variable nozzle  136  and the vane  132  is between 10° and 25° when the restrictor member  130  is in a closed position. Moreover, regardless of the configuration, it is preferable that the combination of the restrictor member  130  and the vane  132  have a center of gravity aligned with the shaft  134 , or the axis of rotation. In full view of the present disclosure, it should be apparent to those skilled in the art that the angle of the vane  132  may be limited by the size or shape of the housing  102 , and will generally be less than half the total rotation of the vane  132  and the restrictor member  130 . 
     Turning to  FIGS. 12 and 13 , a front perspective view and a rear perspective view of the variable nozzle  136  is shown without the flow of exhaled air therethrough. In general, the variable nozzle  136  includes top and bottom walls  146 , side walls  148 , and V-shaped slits  150  formed therebetween. As shown, the variable nozzle is generally shaped like a duck-bill type valve. However, it should be appreciated that nozzles or valves of other shapes and sizes may also be used. The variable nozzle  136  may also include a lip  152  configured to mount the variable nozzle  136  within the housing  102  between the first chamber  114  and the second chamber  118 . The variable nozzle  136  may be constructed or molded of any material having a suitable flexibility, such as silicone, and preferably with a wall thickness of between 0.50 and 2.00 millimeters, and an orifice width between 0.25 to 1.00 millimeters, or smaller depending on manufacturing capabilities. 
     As previously described, the variable nozzle  136  is optional in the operation of the OPEP device  100 . It should also be appreciated that the OPEP device  100  could alternatively omit both the chamber passage  116  and the variable nozzle  136 , and thus comprise a single-chamber embodiment. Although functional without the variable nozzle  136 , the performance of the OPEP device  100  over a wider range of exhalation flow rates is improved when the OPEP device  100  is operated with the variable nozzle  136 . The chamber passage  116 , when used without the variable nozzle  136 , or the orifice  138  of the variable nozzle  136 , when the variable nozzle  136  is included, serves to create a jet of exhaled air having an increased velocity. As explained in more detail below, the increased velocity of the exhaled air entering the second chamber  118  results in a proportional increase in the force applied by the exhaled air to the vane  132 , and in turn, an increased torque about the shaft  134 , all of which affect the ideal operating conditions. 
     Without the variable nozzle  136 , the orifice between the first chamber  114  and the second chamber  118  is fixed according to the size, shape, and cross-sectional area of the chamber passage  116 , which may be selectively adjusted by any suitable means, such as replacement of the middle section  103  or the rear section  105  of the housing. On the other hand, when the variable nozzle  136  is included in the OPEP device  100 , the orifice between the first chamber  114  and the second chamber  118  is defined by the size, shape, and cross-sectional area of the orifice  138  of the variable nozzle  136 , which may vary according to the flow rate of exhaled air and/or the pressure in the first chamber  114 . 
     Turning to  FIG. 14 , a front perspective view of the variable nozzle  136  is shown with a flow of exhaled air therethrough. One aspect of the variable nozzle  136  shown in  FIG. 14  is that, as the orifice  138  opens in response to the flow of exhaled air therethrough, the cross-sectional shape of the orifice  138  remains generally rectangular, which during the administration of OPEP therapy results in a lower drop in pressure through the variable nozzle  136  from the first chamber  114  (See  FIGS. 3 and 5 ) to the second chamber  118 . The generally consistent rectangular shape of the orifice  138  of the variable nozzle  136  during increased flow rates is achieved by the V-shaped slits  150  formed between the top and bottom walls  146  and the side walls  148 , which serve to permit the side walls  148  to flex without restriction. Preferably, the V-shaped slits  150  are as thin as possible to minimize the leakage of exhaled air therethrough. For example, the V-shaped slits  150  may be approximately 0.25 millimeters wide, but depending on manufacturing capabilities, could range between 0.10 and 0.50 millimeters. Exhaled air that does leak through the V-shaped slits  150  is ultimately directed along the exhalation flow path by the guide walls  120  in the second chamber  118  protruding from the housing  102 . 
     It should be appreciated that numerous factors contribute to the impact the variable nozzle  136  has on the performance of the OPEP device  100 , including the geometry and material of the variable nozzle  136 . By way of example only, in order to attain a target oscillating pressure frequency of between 10 to 13 Hz at an exhalation flow rate of 15 liters per minute, in one embodiment, a 1.0 by 20.0 millimeter passage or orifice may be utilized. However, as the exhalation flow rate increases, the frequency of the oscillating pressure in that embodiment also increases, though at a rate too quickly in comparison to the target frequency. In order to attain a target oscillating pressure frequency of between 18 to 20 Hz at an exhalation flow rate of 45 liters per minute, the same embodiment may utilize a 3.0 by 20.0 millimeter passage or orifice. Such a relationship demonstrates the desirability of a passage or orifice that expands in cross-sectional area as the exhalation flow rate increases in order to limit the drop in pressure across the variable nozzle  136 . 
     Turning to  FIGS. 15A-C , top phantom views of the OPEP device  100  show an exemplary illustration of the operation of the OPEP device  100 . Specifically,  FIG. 15A  shows the restrictor member  130  in an initial, or closed position, where the flow of exhaled air through the chamber inlet  104  is restricted, and the vane  132  is in a first position, directing the flow of exhaled air toward the first chamber outlet  106 .  FIG. 15B  shows this restrictor member  130  in a partially open position, where the flow of exhaled air through the chamber inlet  104  is less restricted, and the vane  132  is directly aligned with the jet of exhaled air exiting the variable nozzle  136 .  FIG. 15C  shows the restrictor member  130  in an open position, where the flow of exhaled air through the chamber inlet  104  is even less restricted, and the vane  132  is in a second position, directing the flow of exhaled air toward the second chamber outlet  108 . It should be appreciated that the cycle described below is merely exemplary of the operation of the OPEP device  100 , and that numerous factors may affect operation of the OPEP device  100  in a manner that results in a deviation from the described cycle. However, during the operation of the OPEP device  100 , the restrictor member  130  and the vane  132  will generally reciprocate between the positions shown in  FIGS. 15A and 15C . 
     During the administration of OPEP therapy, the restrictor member  130  and the vane  132  may be initially positioned as shown in  FIG. 15A . In this position, the restrictor member  130  is in a closed position, where the flow of exhaled air along the exhalation path through the chamber inlet  104  is substantially restricted. As such, an exhalation pressure at the chamber inlet  104  begins to increase when a user exhales into the mouthpiece  108 . As the exhalation pressure at the chamber inlet  104  increases, a corresponding force acting on the face  140  of the restrictor member  130  increases. As previously explained, because the center  144  of the face  140  is offset from the plane defined by the radial offset and the shaft  134 , a resulting net force creates a negative or opening torque about the shaft. In turn, the opening torque biases the restrictor member  130  to rotate open, letting exhaled air enter the first chamber  114 , and biases the vane  132  away from its first position. As the restrictor member  130  opens and exhaled air is let into the first chamber  114 , the pressure at the chamber inlet  104  begins to decrease, the force acting on the face  140  of the restrictor member begins to decrease, and the torque biasing the restrictor member  130  open begins to decrease. 
     As exhaled air continues to enter the first chamber  114  through the chamber inlet  104 , it is directed along the exhalation flow path  110  by the housing  102  until it reaches the chamber passage  116  disposed between the first chamber  114  and the second chamber  118 . If the OPEP device  100  is being operated without the variable nozzle  136 , the exhaled air accelerates through the chamber passage  116  due to the decrease in cross-sectional area to form a jet of exhaled air. Likewise, if the OPEP device  100  is being operated with the variable nozzle  136 , the exhaled air accelerates through the orifice  138  of the variable nozzle  136 , where the pressure through the orifice  138  causes the side walls  148  of the variable nozzle  136  to flex outward, thereby increasing the size of the orifice  138 , as well as the resulting flow of exhaled air therethrough. To the extent some exhaled air leaks out of the V-shaped slits  150  of the variable nozzle  136 , it is directed back toward the jet of exhaled air and along the exhalation flow path by the guide walls  120  protruding into the housing  102 . 
     Then, as the exhaled air exits the first chamber  114  through the variable nozzle  136  and/or chamber passage  116  and enters the second chamber  118 , it is directed by the vane  132  toward the front section  101  of the housing  102 , where it is forced to reverse directions before exiting the OPEP device  100  through the open first chamber exit  106 . As a result of the change in direction of the exhaled air toward the front section  101  of the housing  102 , a pressure accumulates in the second chamber  118  near the front section  101  of the housing  102 , thereby resulting in a force on the adjacent vane  132 , and creating an additional negative or opening torque about the shaft  134 . The combined opening torques created about the shaft  134  from the forces acting on the face  140  of the restrictor member  130  and the vane  132  cause the restrictor member  130  and the vane  132  to rotate about the shaft  134  from the position shown in  FIG. 15A  toward the position shown in  FIG. 15B . 
     When the restrictor member  130  and the vane  132  rotate to the position shown in  FIG. 15B , the vane  132  crosses the jet of exhaled air exiting the variable nozzle  136  or the chamber passage  116 . Initially, the jet of exhaled air exiting the variable nozzle  136  or chamber passage  116  provides a force on the vane  132  that, along with the momentum of the vane  132 , the shaft  134 , and the restrictor member  130 , propels the vane  132  and the restrictor member  130  to the position shown in  FIG. 15C . However, around the position shown in  FIG. 15B , the force acting on the vane  132  from the exhaled air exiting the variable nozzle  136  also switches from a negative or opening torque to a positive or closing torque. More specifically, as the exhaled air exits the first chamber  114  through the variable nozzle  136  and enters the second chamber  118 , it is directed by the vane  132  toward the front section  101  of the housing  102 , where it is forced to reverse directions before exiting the OPEP device  100  through the open second chamber exit  108 . As a result of the change in direction of the exhaled air toward the front section  101  of the housing  102 , a pressure accumulates in the second chamber  118  near the front section  101  of the housing  102 , thereby resulting in a force on the adjacent vane  132 , and creating a positive or closing torque about the shaft  134 . As the vane  132  and the restrictor member  130  continue to move closer to the position shown in  FIG. 15C , the pressure accumulating in the section chamber  118  near the front section  101  of the housing  102 , and in turn, the positive or closing torque about the shaft  134 , continues to increase, as the flow of exhaled air along the exhalation flow path  110  and through the chamber inlet  104  is even less restricted. Meanwhile, although the torque about the shaft  134  from the force acting on the restrictor member  130  also switches from a negative or opening torque to a positive or closing torque around the position shown in  FIG. 15B , its magnitude is essentially negligible as the restrictor member  130  and the vane  132  rotate from the position shown in  FIG. 15B  to the position shown in  FIG. 15C . 
     After reaching the position shown in  FIG. 15C , and due to the increased positive or closing torque about the shaft  134 , the vane  132  and the restrictor member  130  reverse directions and begin to rotate back toward the position shown in  FIG. 15B . As the vane  132  and the restrictor member  130  approach the position shown in  FIG. 15B , and the flow of exhaled through the chamber inlet  104  is increasingly restricted, the positive or closing torque about the shaft  134  begins to decrease. When the restrictor member  130  and the vane  132  reach the position  130  shown in  FIG. 15B , the vane  132  crosses the jet of exhaled air exiting the variable nozzle  136  or the chamber passage  116 , thereby creating a force on the vane  132  that, along with the momentum of the vane  132 , the shaft  134 , and the restrictor member  130 , propels the vane  132  and the restrictor member  130  back to the position shown in  FIG. 15A . After the restrictor member  130  and the vane  132  return to the position shown in  FIG. 15A , the flow of exhaled air through the chamber inlet  104  is restricted, and the cycle described above repeats itself. 
     It should be appreciated that, during a single period of exhalation, the cycle described above will repeat numerous times. Thus, by repeatedly moving the restrictor member  130  between a closed position, where the flow of exhaled air through the chamber inlet  104  is restricted, and an open position, where the flow of exhaled air through the chamber inlet  104  is less restricted, an oscillating back pressure is transmitted to the user of the OPEP device  100  and OPEP therapy is administered. 
     Turning now to  FIGS. 16-17 , an alternative embodiment of a variable nozzle  236  is shown. The variable nozzle  236  may be used in the OPEP device  100  as an alternative to the variable nozzle  136  described above. As shown in  FIGS. 16-17 , the variable nozzle  236  includes an orifice  238 , top and bottom walls  246 , side walls  248 , and a lip  252  configured to mount the variable nozzle  236  within the housing of the OPEP device  100  between the first chamber  114  and the second chamber  118  in the same manner as the variable nozzle  136 . Similar to the variable nozzle  136  shown in  FIGS. 12-13 , the variable nozzle  236  may be constructed or molded of any material having a suitable flexibility, such as silicone. 
     During the administration of OPEP therapy, as the orifice  238  of the variable nozzle  236  opens in response to the flow of exhaled air therethrough, the cross-sectional shape of the orifice  238  remains generally rectangular, which results in a lower drop in pressure through the variable nozzle  236  from the first chamber  114  to the second chamber  118 . The generally consistent rectangular shape of the orifice  238  of the variable nozzle  236  during increased flow rates is achieved by thin, creased walls formed in the top and bottom walls  246 , which allow the side walls  248  to flex easier and with less resistance. A further advantage of this embodiment is that there is no leakage out of the top and bottom walls  246  while exhaled air flows through the orifice  238  of the variable nozzle  236 , such as for example, through the V-shaped slits  150  of the variable nozzle  136  shown in  FIGS. 12-13 . 
     Those skilled in the art will also appreciate that, in some applications, only positive expiratory pressure (without oscillation) may be desired, in which case the OPEP device  100  may be operated without the restrictor member  130 , but with a fixed orifice or manually adjustable orifice instead. The positive expiratory pressure embodiment may also comprise the variable nozzle  136 , or the variable nozzle  236 , in order to maintain a relatively consistent back pressure within a desired range. 
     Second OPEP Embodiment 
     Turning now to  FIGS. 18-19 , a front perspective view and a rear perspective view of a second embodiment of an OPEP device  200  is shown. The configuration and operation of the OPEP device  200  is similar to that of the OPEP device  100 . However, as best shown in  FIGS. 20-24 , the OPEP device  200  further includes an adjustment mechanism  253  adapted to change the relative position of the chamber inlet  204  with respect to the housing  202  and the restrictor member  230 , which in turn changes the range of rotation of the vane  232  operatively connected thereto. As explained below, a user is therefore able to conveniently adjust both the frequency and the amplitude of the OPEP therapy administered by the OPEP device  200  without opening the housing  202  and disassembling the components of the OPEP device  200 . 
     The OPEP device  200  generally comprises a housing  202 , a chamber inlet  204 , a first chamber outlet  206  (best seen in  FIGS. 23 and 32 ), a second chamber outlet  208  (best seen in  FIGS. 23 and 32 ), and a mouthpiece  209  in fluid communication with the chamber inlet  204 . As with the OPEP device  100 , a front section  201 , a middle section  203 , and a rear section  205  of the housing  202  are separable so that the components contained therein can be periodically accessed, cleaned, replaced, or reconfigured, as required to maintain the ideal operating conditions. The OPEP device also includes an adjustment dial  254 , as described below. 
     As discussed above in relation to the OPEP device  100 , the OPEP device  200  may be adapted for use with other or additional interfaces, such as an aerosol delivery device. In this regard, the OPEP device  200  is equipped with an inhalation port  211  (best seen in  FIGS. 19, 21, and 23 ) in fluid communication with the mouthpiece  209  and the chamber inlet  204 . As noted above, the inhalation port may include a separate one-way valve (not shown) to permit a user of the OPEP device  200  both to inhale the surrounding air through the one-way valve and to exhale through the chamber inlet  204  without withdrawing the mouthpiece  209  of the OPEP device  200  between periods of inhalation and exhalation. In addition, the aforementioned aerosol delivery devices may be connected to the inhalation port  211  for the simultaneous administration of aerosol and OPEP therapies. 
     An exploded view of the OPEP device  200  is shown in  FIG. 20 . In addition to the components of the housing described above, the OPEP device  200  includes a restrictor member  230  operatively connected to a vane  232  by a pin  231 , an adjustment mechanism  253 , and a variable nozzle  236 . As shown in the cross-sectional view of  FIG. 21 , when the OPEP device  200  is in use, the variable nozzle  236  is positioned between the middle section  203  and the rear section  205  of the housing  202 , and the adjustment mechanism  253 , the restrictor member  230 , and the vane  232  form an assembly. 
     Turning to  FIGS. 21-23 , various cross-sectional perspective views of the OPEP device  200  are shown. As with the OPEP device  100 , an exhalation flow path  210 , identified by a dashed line, is defined between the mouthpiece  209  and at least one of the first chamber outlet  206  and the second chamber outlet  208  (best seen in  FIGS. 23 and 32 ). As a result of a one-way valve (not-shown) and/or an aerosol delivery device (not shown) attached to the inhalation port  211 , the exhalation flow path  210  begins at the mouthpiece  209  and is directed toward the chamber inlet  204 , which in operation may or may not be blocked by the restrictor member  230 . After passing through the chamber inlet  204 , the exhalation flow path  210  enters a first chamber  214  and makes a 180° turn toward the variable nozzle  236 . After passing through the orifice  238  of the variable nozzle  236 , the exhalation flow path  210  enters a second chamber  218 . In the second chamber  218 , the exhalation flow path  210  may exit the OPEP device  200  through at least one of the first chamber outlet  206  or the second chamber outlet  208 . Those skilled in the art will appreciate that the exhalation flow path  210  identified by the dashed line is exemplary, and that air exhaled into the OPEP device  200  may flow in any number of directions or paths as it traverses from the mouthpiece  209  or chamber inlet  204  to the first chamber outlet  206  or the second chamber outlet  208 . 
     Referring to  FIGS. 24-25 , front and rear perspective views of the adjustment mechanism  253  of the OPEP device  200  are shown. In general, the adjustment mechanism  253  includes an adjustment dial  254 , a shaft  255 , and a frame  256 . A protrusion  258  is positioned on a rear face  260  of the adjustment dial, and is adapted to limit the selective rotation of the adjustment mechanism  253  by a user, as further described below. The shaft  255  includes keyed portions  262  adapted to fit within upper and lower bearings  226 ,  228  formed in the housing  200  (see  FIGS. 21 and 28-29 ). The shaft further includes an axial bore  264  configured to receive the pin  231  operatively connecting the restrictor member  230  and the vane  232 . As shown, the frame  256  is spherical, and as explained below, is configured to rotate relative to the housing  202 , while forming a seal between the housing  202  and the frame  256  sufficient to permit the administration of OPEP therapy. The frame  256  includes a circular opening defined by a seat  224  adapted to accommodate the restrictor member  230 . In use, the circular opening functions as the chamber inlet  204 . The frame  256  also includes a stop  222  for preventing the restrictor member  230  from opening in a wrong direction. 
     Turning to  FIG. 26 , a front perspective view of the restrictor member  230  and the vane  232  is shown. The design, materials, and configuration of the restrictor member  230  and the vane  232  may be the same as described above in regards to the OPEP device  100 . However, the restrictor member  230  and the vane  232  in the OPEP device  200  are operatively connected by a pin  231  adapted for insertion through the axial bore  264  in the shaft  255  of the adjustment mechanism  253 . The pin  231  may be constructed, for example, by stainless steel. In this way, rotation of the restrictor member  230  results in a corresponding rotation of the vane  232 , and vice versa. 
     Turning to  FIG. 27 , a front perspective view of the adjustment mechanism  253  assembled with the restrictor member  230  and the vane  232  is shown. In this configuration, it can be seen that the restrictor member  230  is positioned such that it is rotatable relative to the frame  256  and the seat  224  between a closed position (as shown), where a flow of exhaled air along the exhalation flow path  210  through the chamber inlet  204  is restricted, and an open position (not shown), where the flow of exhaled air through the chamber inlet  204  is less restricted. As previously mentioned the vane  232  is operatively connected to the restrictor member  230  by the pin  231  extending through shaft  255 , and is adapted to move in unison with the restrictor member  230 . It can further be seen that the restrictor member  230  and the vane  232  are supported by the adjustment mechanism  253 , which itself is rotatable within the housing  202  of the OPEP device  200 , as explained below. 
       FIGS. 28 and 29A -B are partial cross-sectional views illustrating the adjustment mechanism  253  mounted within the housing  202  of the OPEP device  200 . As shown in  FIG. 28 , the adjustment mechanism  253 , as well as the restrictor member  230  and the vane  232 , are rotatably mounted within the housing  200  about an upper and lower bearing  226 ,  228 , such that a user is able to rotate the adjustment mechanism  253  using the adjustment dial  254 .  FIGS. 29A-29B  further illustrates the process of mounting and locking the adjustment mechanism  253  within the lower bearing  228  of the housing  202 . More specifically, the keyed portion  262  of the shaft  255  is aligned with and inserted through a rotational lock  166  formed in the housing  202 , as shown in  FIG. 29A . Once the keyed portion  262  of the shaft  255  is inserted through the rotational lock  266 , the shaft  255  is rotated 90° to a locked position, but remains free to rotate. The adjustment mechanism  253  is mounted and locked within the upper bearing  226  in the same manner. 
     Once the housing  200  and the internal components of the OPEP device  200  are assembled, the rotation of the shaft  255  is restricted to keep it within a locked position in the rotational lock  166 . As shown in a front view of the OPEP device  200  in  FIG. 30 , two stops  268 ,  288  are positioned on the housing  202  such that they engage the protrusion  258  formed on the rear face  260  of the adjustment dial  254  when a user rotates the adjustment dial  254  to a predetermined position. For purposes of illustration, the OPEP device  200  is shown in  FIG. 30  without the adjustment dial  254  or the adjustment mechanism  253 , which would extend from the housing  202  through an opening  269 . In this way, rotation of the adjustment dial  254 , the adjustment mechanism  253 , and the keyed portion  262  of the shaft  255  can be appropriately restricted. 
     Turning to  FIG. 31 , a partial cross-sectional view of the adjustment mechanism  253  mounted within the housing  200  is shown. As previously mentioned, the frame  256  of the adjustment mechanism  253  is spherical, and is configured to rotate relative to the housing  202 , while forming a seal between the housing  202  and the frame  256  sufficient to permit the administration of OPEP therapy. As shown in  FIG. 31 , a flexible cylinder  271  extending from the housing  202  completely surrounds a portion of the frame  256  to form a sealing edge  270 . Like the housing  202  and the restrictor member  230 , the flexible cylinder  271  and the frame  256  may be constructed of a low shrink, low friction plastic. One such material is acetal. In this way, the sealing edge  270  contacts the frame  256  for a full 360° and forms a seal throughout the permissible rotation of the adjustment member  253 . 
     The selective adjustment of the OPEP device  200  will now be described with reference to  FIGS. 32A-B ,  33 A-B, and  34 A-B.  FIGS. 32A-B  are partial cross-sectional views of the OPEP device  200 ;  FIGS. 33A-B  are illustrations of the adjustability of the OPEP device  200 ; and,  FIGS. 34A-B  are top phantom views of the OPEP device  200 . As previously mentioned with regards to the OPEP device  100 , it is preferable that the vane  232  and the restrictor member  230  are configured such that when the OPEP device  200  is fully assembled, the angle between a centerline of the variable nozzle  236  and the vane  232  is between 10° and 25° when the restrictor member  230  is in a closed position. However, it should be appreciated that the adjustability of the OPEP device  200  is not limited to the parameters described herein, and that any number of configurations may be selected for purposes of administering OPEP therapy within the ideal operating conditions. 
       FIG. 32A  shows the vane  232  at an angle of 10° from the centerline of the variable nozzle  236 , whereas  FIG. 32B  shows the vane  232  at an angle of 25° from the centerline of the variable nozzle  236 .  FIG. 33A  illustrates the necessary position of the frame  256  (shown in phantom) relative to the variable nozzle  236  such that the angle between a centerline of the variable nozzle  236  and the vane  232  is 10° when the restrictor member  230  is in the closed position.  FIG. 33B , on the other hand, illustrates the necessary position of the frame  256  (shown in phantom) relative to the variable nozzle  236  such that the angle between a centerline of the variable nozzle  236  and the vane  232  is 25° when the restrictor member  230  is in the closed position. 
     Referring to  FIGS. 34A-B , side phantom views of the OPEP device  200  are shown. The configuration shown in  FIG. 34A  corresponds to the illustrations shown in  FIGS. 32A and 33A , wherein the angle between a centerline of the variable nozzle  236  and the vane  232  is 10° when the restrictor member  230  is in the closed position.  FIG. 34B , on the other hand, corresponds to the illustrations shown in  FIGS. 32B and 33B , wherein the angle between a centerline of the variable nozzle  236  and the vane  232  is 25° when the restrictor member  230  is in the closed position. In other words, the frame  256  of the adjustment member  253  has been rotated counter-clockwise 15°, from the position shown in  FIG. 34A , to the position shown in  FIG. 34B , thereby also increasing the permissible rotation of the vane  232 . 
     In this way, a user is able to rotate the adjustment dial  254  to selectively adjust the orientation of the chamber inlet  204  relative to the restrictor member  230  and the housing  202 . For example, a user may increase the frequency and amplitude of the OPEP therapy administered by the OPEP device  200  by rotating the adjustment dial  254 , and therefore the frame  256 , toward the position shown in  FIG. 34A . Alternatively, a user may decrease the frequency and amplitude of the OPEP therapy administered by the OPEP device  200  by rotating the adjustment dial  254 , and therefore the frame  256 , toward the position shown in  FIG. 34B . Furthermore, as shown for example in  FIGS. 18 and 30 , indicia may be provided to aid the user in the setting of the appropriate configuration of the OPEP device  200 . 
     Operating conditions similar to those described below with reference to the OPEP device  800  may also be achievable for an OPEP device according to the OPEP device  200 . 
     Third OPEP Embodiment 
     Turning to  FIGS. 35-37 , another embodiment of an OPEP device  300  is shown. The OPEP device  300  is similar to that of the OPEP device  200  in that is selectively adjustable. As best seen in  FIGS. 35, 37, 40, and 49 , the OPEP device  300 , like the OPEP device  300 , includes an adjustment mechanism  353  adapted to change the relative position of a chamber inlet  304  with respect to a housing  302  and a restrictor member  330 , which in turn changes the range of rotation of a vane  332  operatively connected thereto. As previously explained with regards to the OPEP device  200 , a user is therefore able to conveniently adjust both the frequency and the amplitude of the OPEP therapy administered by the OPEP device  300  without opening the housing  302  and disassembling the components of the OPEP device  300 . The administration of OPEP therapy using the OPEP device  300  is otherwise the same as described above with regards to the OPEP device  100 . 
     The OPEP device  300  comprises a housing  302  having a front section  301 , a rear section  305 , and an inner casing  303 . As with the previously described OPEP devices, the front section  301 , the rear section  305 , and the inner casing  303  are separable so that the components contained therein can be periodically accessed, cleaned, replaced, or reconfigured, as required to maintain the ideal operating conditions. For example, as shown in  FIGS. 35-37 , the front section  301  and the rear section  305  of the housing  302  are removably connected via a snap fit engagement. 
     The components of the OPEP device  300  are further illustrated in the exploded view of  FIG. 38 . In general, in addition to the front section  301 , the rear section  305 , and the inner casing  303 , the OPEP device  300  further comprises a mouthpiece  309 , an inhalation port  311 , a one-way valve  384  disposed therebetween, an adjustment mechanism  353 , a restrictor member  330 , a vane  332 , and a variable nozzle  336 . 
     As seen in  FIGS. 39-40 , the inner casing  303  is configured to fit within the housing  302  between the front section  301  and the rear section  305 , and partially defines a first chamber  314  and a second chamber  318 . The inner casing  303  is shown in further detail in the perspective and cross sectional views shown in  FIGS. 41-42 . A first chamber outlet  306  and a second chamber outlet  308  are formed within the inner casing  303 . One end  385  of the inner casing  303  is adapted to receive the variable nozzle  336  and maintain the variable nozzle  336  between the rear section  305  and the inner casing  303 . An upper bearing  326  and a lower bearing  328  for supporting the adjustment mechanism  353  is formed, at least in part, within the inner casing  303 . Like the flexible cylinder  271  and sealing edge  270  described above with regards to the OPEP device  200 , the inner casing  303  also includes a flexible cylinder  371  with a sealing edge  370  for engagement about a frame  356  of the adjustment mechanism  353 . 
     The vane  332  is shown in further detail in the perspective view shown in  FIG. 43 . A shaft  334  extends from the vane  332  and is keyed to engage a corresponding keyed portion within a bore  365  of the restrictor member  330 . In this way, the shaft  334  operatively connects the vane  332  with the restrictor member  330  such that the vane  332  and the restrictor member  330  rotate in unison. 
     The restrictor member  330  is shown in further detail in the perspective views shown in  FIGS. 44-45 . The restrictor member  330  includes a keyed bore  365  for receiving the shaft  334  extending from the vane  332 , and further includes a stop  322  that limits permissible rotation of the restrictor member  330  relative to a seat  324  of the adjustment member  353 . As shown in the front view of  FIG. 46 , like the restrictor member  330 , the restrictor member  330  further comprises an offset designed to facilitate movement of the restrictor member  330  between a closed position and an open position. More specifically, a greater surface area of the face  340  of the restrictor member  330  is positioned on one side of the bore  365  for receiving the shaft  334  than on the other side of the bore  365 . As described above with regards to the restrictor member  130 , this offset produces an opening torque about the shaft  334  during periods of exhalation. 
     The adjustment mechanism  353  is shown in further detail in the front and rear perspective views of  FIGS. 47 and 48 . In general, the adjustment mechanism includes a frame  356  adapted to engage the sealing edge  370  of the flexible cylinder  371  formed on the inner casing  303 . A circular opening in the frame  356  forms a seat  324  shaped to accommodate the restrictor member  330 . In this embodiment, the seat  324  also defines the chamber inlet  304 . The adjustment mechanism  353  further includes an arm  354  configured to extend from the frame  356  to a position beyond the housing  302  in order to permit a user to selectively adjust the orientation of the adjustment mechanism  353 , and therefore the chamber inlet  304 , when the OPEP device  300  is fully assembled. The adjustment mechanism  353  also includes an upper bearing  385  and a lower bearing  386  for receiving the shaft  334 . 
     An assembly of the vane  332 , the adjustment mechanism  353 , and the restrictor member  330  is shown in the perspective view of  FIG. 49 . As previously explained, the vane  332  and the restrictor member  330  are operatively connected by the shaft  334  such that rotation of the vane  332  results in rotation of the restrictor member  330 , and vice versa. In contrast, the adjustment mechanism  353 , and therefore the seat  324  defining the chamber inlet  304 , is configured to rotate relative to the vane  332  and the restrictor member  330  about the shaft  334 . In this way, a user is able to rotate the arm  354  to selectively adjust the orientation of the chamber inlet  304  relative to the restrictor member  330  and the housing  302 . For example, a user may increase the frequency and amplitude of the OPEP therapy administered by the OPEP device  800  by rotating the arm  354 , and therefore the frame  356 , in a clockwise direction. Alternatively, a user may decrease the frequency and amplitude of the OPEP therapy administered by the OPEP device  300  by rotating the adjustment arm  354 , and therefore the frame  356 , in a counter-clockwise direction. Furthermore, as shown for example in  FIGS. 35 and 37 , indicia may be provided on the housing  302  to aid the user in the setting of the appropriate configuration of the OPEP device  300 . 
     The variable nozzle  336  is shown in further detail in the front and rear perspective views of  FIGS. 50 and 51 . The variable nozzle  336  in the OPEP device  300  is similar to the variable nozzle  236  described above with regards to the OPEP device  200 , except that the variable nozzle  336  also includes a base plate  387  configured to fit within one end  385  (see  FIGS. 41-42 ) of the inner casing  303  and maintain the variable nozzle  336  between the rear section  305  and the inner casing  303 . Like the variable nozzle  236 , the variable nozzle  336  and base plate  387  may be made of silicone. 
     The one-way valve  384  is shown in further detail in the front perspective view of  FIG. 52 . In general, the one-way valve  384  comprises a post  388  adapted for mounting in the front section  301  of the housing  302 , and a flap  389  adapted to bend or pivot relative to the post  388  in response to a force or a pressure on the flap  389 . Those skilled in the art will appreciate that other one-way valves may be used in this and other embodiments described herein without departing from the teachings of the present disclosure. As seen in  FIGS. 39-40 , the one-way valve  384  may be positioned in the housing  302  between the mouthpiece  309  and the inhalation port  311 . 
     As discussed above in relation to the OPEP device  100 , the OPEP device  300  may be adapted for use with other or additional interfaces, such as an aerosol delivery device. In this regard, the OPEP device  300  is equipped with an inhalation port  311  (best seen in  FIGS. 35-36 and 38-40 ) in fluid communication with the mouthpiece  309 . As noted above, the inhalation port may include a separate one-way valve  384  (best seen in  FIGS. 39-40 and 52 ) configured to permit a user of the OPEP device  300  both to inhale the surrounding air through the one-way valve  384  and to exhale through the chamber inlet  304 , without withdrawing the mouthpiece  309  of the OPEP device  300  between periods of inhalation and exhalation. In addition, the aforementioned commercially available aerosol delivery devices may be connected to the inhalation port  311  for the simultaneous administration of aerosol therapy (upon inhalation) and OPEP therapy (upon exhalation). 
     The OPEP device  300  and the components described above are further illustrated in the cross-sectional views shown in  FIGS. 39-40 . For purposes of illustration, the cross-sectional view of  FIG. 39  is shown without all the internal components of the OPEP device  300 . 
     The front section  301 , the rear section  305 , and the inner casing  303  are assembled to form a first chamber  314  and a second chamber  318 . As with the OPEP device  100 , an exhalation flow path  310 , identified by a dashed line, is defined between the mouthpiece  309  and at least one of the first chamber outlet  306  (best seen in  FIGS. 39-40 and 42 ) and the second chamber outlet  308  (best seen in  FIG. 41 ), both of which are formed within the inner casing  303 . As a result of the inhalation port  311  and the one-way valve  348 , the exhalation flow path  310  begins at the mouthpiece  309  and is directed toward the chamber inlet  304 , which in operation may or may not be blocked by the restrictor member  330 . After passing through the chamber inlet  304 , the exhalation flow path  310  enters the first chamber  314  and makes a 180° turn toward the variable nozzle  336 . After passing through an orifice  338  of the variable nozzle  336 , the exhalation flow path  310  enters the second chamber  318 . In the second chamber  318 , the exhalation flow path  310  may exit the second chamber  318 , and ultimately the housing  302 , through at least one of the first chamber outlet  306  or the second chamber outlet  308 . Those skilled in the art will appreciate that the exhalation flow path  310  identified by the dashed line is exemplary, and that air exhaled into the OPEP device  300  may flow in any number of directions or paths as it traverses from the mouthpiece  309  or chamber inlet  304  to the first chamber outlet  306  or the second chamber outlet  308 . As previously noted, the administration of OPEP therapy using the OPEP device  300  is otherwise the same as described above with regards to the OPEP device  100 . 
     Solely by way of example, the follow operating conditions, or performance characteristics, may be achieved by an OPEP device according to the OPEP device  300 , with the adjustment dial  354  set for increased frequency and amplitude: 
                                        Flow Rate (Ipm)   10     30       Frequency (Hz)   7     20       Upper Pressure (cm H2O)   13     30       Lower Pressure (cm H2O)   1.5    9       Amplitude (cm H2O)   11.5    21                    
The frequency and amplitude may decrease, for example, by approximately 20% with the adjustment dial  354  set for decreased frequency and amplitude. Other frequency and amplitude targets may be achieved by varying the particular configuration or sizing of elements, for example, increasing the length of the vane  332  results in a slower frequency, whereas, decreasing the size of the orifice  338  results in a higher frequency. The above example is merely one possible set of operating conditions for an OPEP device according to the embodiment described above.
 
     Fourth OPEP Embodiment 
     Turning to  FIGS. 53-56 , another embodiment of a respiratory treatment device  400  is shown. Unlike the previously described OPEP devices, the respiratory treatment device  400  is configured to administer oscillating pressure therapy upon both exhalation and inhalation. Those skilled in the art will appreciate that the concepts described below with regards to the respiratory treatment device  400  may be applied to any of the previously described OPEP devices, such that oscillating pressure therapy may be administered upon both exhalation and inhalation. Likewise, the respiratory treatment device  400  may incorporate any of the concepts above regarding the previously described OPEP devices, including for example, a variable nozzle, an inhalation port adapted for use with an aerosol delivery device for the administration of aerosol therapy, an adjustment mechanism, etc. 
     As shown in  FIGS. 53 and 54 , the respiratory treatment device  400  includes a housing  402  having a front section  401 , a middle section  403 , and a rear section  405 . As with the OPEP devices described above, the housing  402  is openable so that the contents of the housing  402  may be accessed for cleaning and/or selective replacement or adjustment of the components contained therein to maintain ideal operating conditions. The housing  402  further includes a first opening  412 , a second opening  413 , and a third opening  415 . 
     Although the first opening  412  is shown in in  FIGS. 53 and 54  in association with a mouthpiece  409 , the first opening  412  may alternatively be associated with other user interfaces, for example, a gas mask or a breathing tube. The second opening  413  includes a one-way exhalation valve  490  configured to permit air exhaled into the housing  402  to exit the housing  402  upon exhalation at the first opening  412 . The third opening  415  includes a one-way inhalation valve  484  configured to permit air outside the housing  402  to enter the housing  402  upon inhalation at the first opening  412 . As shown in greater detail in  FIG. 54 , the respiratory treatment device  400  further includes a manifold plate  493  having an exhalation passage  494  and an inhalation passage  495 . A one-way valve  491  is adapted to mount to within the manifold plate  493  adjacent to the exhalation passage  494  such that the one-way valve  491  opens in response to air exhaled into the first opening  412 , and closes in response to air inhaled through the first opening  412 . A separate one-way valve  492  is adapted to mount within the manifold pate  493  adjacent to the inhalation passage  495  such that the one-way valve  492  closes in response to air exhaled into the first opening  412 , and opens in response to air inhaled through the first opening  412 . The respiratory treatment device  400  also includes a restrictor member  430  and a vane  432  operatively connected by a shaft  434 , the assembly of which may operate in the same manner as described above with regards to the disclosed OPEP devices. 
     Referring now to  FIGS. 55 and 56 , cross-sectional perspective views are shown taken along lines I and II, respectively, in  FIG. 53 . The respiratory treatment device  400  administers oscillating pressure therapy upon both inhalation and exhalation in a manner similar to that shown and described above with regards to the OPEP devices. As described in further detail below, the OPEP device  400  includes a plurality of chambers (i.e., more than one). Air transmitted through the first opening  412  of the housing  402 , whether inhaled or exhaled, traverses a flow path that passes, at least in part, past a restrictor member  430  housed in a first chamber  414 , and through a second chamber  418  which houses a vane  432  operatively connected to the restrictor member  430 . In this regard, at least a portion of the flow path for both air exhaled into or inhaled from the first opening  412  is overlapping, and occurs in the same direction. 
     For example, an exemplary flow path  481  is identified in  FIGS. 55 and 56  by a dashed line. Similar to the previously described OPEP devices, the restrictor member  430  is positioned in the first chamber  414  and is movable relative to a chamber inlet  404  between a closed position, where the flow of air through the chamber inlet  404  is restricted, and an open position, where the flow of air through the chamber  404  inlet is less restricted. After passing through the chamber inlet  404  and entering the first chamber  414 , the exemplary flow path  481  makes a 180-degree turn, or reverses longitudinal directions (i.e., the flow path  481  is folded upon itself), whereupon the exemplary flow path  481  passes through an orifice  438  and enters the second chamber  418 . As with the previously described OPEP devices, the vane  432  is positioned in the second chamber  418 , and is configured to reciprocate between a first position and a second position in response to an increased pressure adjacent the vane, which in turn causes the operatively connected restrictor member  430  to repeatedly move between the closed position and the open position. Depending on the position of the vane  432 , air flowing along the exemplary flow path  481  is directed to one of either a first chamber outlet  406  or a second chamber outlet  408 . Consequently, as inhaled or exhaled air traverses the exemplary flow path  481 , pressure at the chamber inlet  404  oscillates. 
     The oscillating pressure at the chamber inlet  404  is effectively transmitted back to a user of the respiratory treatment device  400 , i.e., at the first opening  412 , via a series of chambers. As seen in  FIGS. 55 and 56 , the respiratory treatment device includes a first additional chamber  496 , a second additional chamber  497 , and a third additional chamber  498 , which are described in further detail below. 
     The mouthpiece  409  and the first additional chamber  496  are in communication via the first opening  412  in the housing  402 . The first additional chamber  496  and the second additional chamber  497  are separated by the manifold plate  493 , and are in communication via the exhalation passage  494 . The one-way valve  491  mounted adjacent to the exhalation passage  494  is configured to open in response to air exhaled into the first opening  412 , and close in response to air inhaled through the first opening  412 . 
     The first additional chamber  496  and the third additional chamber  498  are also separated by the manifold plate  493 , and are in communication via the inhalation passage  495 . The one-way valve  492  mounted adjacent to the inhalation passage  495  is configured to close in response to air exhaled into the first opening  412 , and open in response to air inhaled through the first opening  412 . 
     Air surrounding the respiratory treatment device  400  and the second additional chamber  497  are in communication via the third opening  415  in the housing  402 . The one-way valve  484  is configured to close in response to air exhaled in to the first opening  412 , and open in response to air inhaled through the first opening  412 . 
     Air surrounding the respiratory treatment device  400  and the third additional chamber  498  are in communication via the second opening  413  in the housing  402 . The one way-valve  490  mounted adjacent the second opening  413  is configured to open in response to air exhaled into the first opening  412 , and close in response to air inhaled through the first opening  412 . The third additional chamber  498  is also in communication with the second chamber  418  via the first chamber outlet  406  and the second chamber outlet  408 . 
     Referring now to  FIGS. 57-58 , cross-sectional perspective views taken along lines I and II, respectively, of  FIG. 53 , illustrate an exemplary exhalation flow path  410  formed between the first opening  412 , or the mouthpiece  409 , and the second opening  413 . In general, upon exhalation by a user into the first opening  412  of the housing  402 , pressure builds in the first additional chamber  496 , causing the one-way valve  491  to open, and the one-way valve  492  to close. Exhaled air then enters the second additional chamber  497  through the exhalation passage  494  and pressure builds in the second additional chamber  497 , causing the one-way valve  484  to close and the restrictor member  430  to open. The exhaled air then enters the first chamber  414  through the chamber inlet  404 , reverses longitudinal directions, and accelerates through the orifice  438  separating the first chamber  414  and the second chamber  418 . Depending on the orientation of the vane  432 , the exhaled air then exits the second chamber  418  through one of either the first chamber outlet  406  or the second chamber outlet  408 , whereupon it enters the third additional chamber  498 . As pressure builds in the third additional chamber  498 , the one-way valve  490  opens, permitting exhaled air to exit the housing  402  through the second opening  413 . Once the flow of exhaled air along the exhalation flow path  410  is established, the vane  432  reciprocates between a first position and a second position, which in turn causes the restrictor member  430  to move between the closed position and the open position, as described above with regards to the OPEP devices. In this way, the respiratory treatment device  400  provides oscillating therapy upon exhalation. 
     Referring now to  FIGS. 59-60 , different cross-sectional perspective views taken along lines I and II, respectively, of  FIG. 53 , illustrate an exemplary inhalation flow path  499  formed between the third opening  415  and the first opening  412 , or the mouthpiece  409 . In general, upon inhalation by a user through the first opening  412 , pressure drops in the first additional chamber  496 , causing the one-way valve  491  to close, and the one-way valve  492  to open. As air is inhaled from the third additional chamber  498  into the first additional chamber  496  through the inhalation passage  495 , pressure in the third additional chamber  498  begins to drop, causing the one-way valve  490  to close. As pressure continues to drop in the third additional chamber  498 , air is drawn from the second chamber  418  through the first chamber outlet  406  and the second camber outlet  408 , As air is drawn from the second chamber  918 , air is also drawn from the first chamber  414  through the orifice  438  connecting the second chamber  418  and the first chamber  414 . As air is drawn from the first chamber  414 , air is also drawn from the second additional chamber  497  through the chamber inlet  404 , causing the pressure in the second additional chamber  497  to drop and the one-way valve  484  to open, thereby permitting air to enter the housing  402  through third opening  415 . Due to the pressure differential between the first additional chamber  496  and the second additional chamber  497 , the one-way valve  491  remains closed. Once the flow of inhaled air along the inhalation flow path  499  is established, the vane  432  reciprocates between a first position and a second position, which in turn causes the restrictor member  430  to move between the closed position and the open position, as described above with regards to the OPEP devices. In this way, the respiratory treatment device  400  provides oscillating therapy upon inhalation. 
     Respiratory Muscle Training 
     RMT includes pressure threshold resistance. A pressure threshold resistor requires a user to achieve and maintain a set pressure in order to inhale or exhale through the pressure threshold resistor and/or the attached respiratory device. In general, a pressure threshold resistor includes a one way valve that is biased toward a closed position. As a pressure force created by a user inhaling through or exhaling into the device overcomes the biasing force, the valve opens and permits inhalation or exhalation. In order to continue with inhalation or exhalation, the user must generate and maintain a pressure that matches or exceeds the pressure threshold that overcomes the biasing force on the valve. A pressure threshold resistor may be use during inhalation to generate a negative pressure for administration of RMT, and during exhalation to generate a positive pressure for administration of RMT. 
     RMT also include flow resistance. A flow resistor limits the flow of air during inhalation or exhalation through the flow resistor and/or the attached respiratory device in order to generate negative or positive pressure for administration RMT. In general, a flow resistor restricts the flow of air through an orifice. The pressure generated by the flow restrictor may be controlled by changing the size of the orifice and/or an inhalation or exhalation flow rate. 
     Pressure Threshold Resistors 
     Turning to  FIGS. 61A-E , perspective, side, top, cross-sectional, and exploded views of a pressure threshold resistor  500  are shown. In general, as shown in  FIGS. 61D and 61E , the pressure threshold resistor  500  includes a spring seat  501 , a spring  502 , an adjuster  503 , a connector  504 , and a valve  505 . 
     The connector  504  may be shaped and size to be removably connectable to the inhalation port of any number of respiratory devices, including for example, the inhalation port  311  of OPEP device  300 . The connector  504  may be removabaly connectable to respiratory devices by any suitable means, including a friction fit, threaded engagement, a snap fit, or the like. 
     A center cylinder  509  of the connector  504  is configured to receive the adjuster  503  via a threaded engagement. An end of the center cylinder  509  also functions as a seat for the valve  505 . 
     The adjuster  503  functions as a thumb screw and is configured for threaded engagement with the connector  504 . In this way, the adjuster  503  may be rotated by a user relative to the connector  504  to raise or lower the position of the adjuster  503  relative to the connector  504 . As discussed below, the adjuster  503  may be selectively rotated by a user to increase or decrease the threshold pressure required to open the valve  505 . The adjuster  503  also includes a center cylinder  506  sized for sliding engagement with the spring  502 . The center cylinder  506  also includes an interior portion sized for sliding engagement with a post  508  of the valve  505 . The base of the center cylinder  506  acts as stop for the spring  502 . 
     The valve  505  includes a valve face  507  and a post  508 . The valve face  507  is configured to engage the seat defined by an end of the cylinder  509  of the connector  504 . As stated above, the post  508  is configured to fit within and be in sliding engagement with the center cylinder  506  of the adjuster  503 . An end of the post  508  is connected to the spring seat  501 . In an alternative embodiment, the end of the post  508  may be removably connected t the spring seat  501 . 
     The spring seat  501  is shaped and sized to fit within the adjuster  503 . In general, the spring seat  501  is cylindrical and includes an interior portion that receives the spring  502  and the post  508  of the valve  505 . A base of the interior portion of the spring seat  501  also acts as stop for the spring  502 . 
     The spring  502  may be a coil spring. Springs of different lengths and spring constants (k) may be selected and/or replaced, as desired, to increase or decrease the threshold pressures required to open the valve  505 . When assembled in the pressure threshold resistor  500  as shown, the spring  502  is under compression. 
     In operation, the pressure threshold resistor  500  is connected to an inhalation port of a respiratory device via the connector  504 . When a user inhales through the respiratory device, a negative pressure is created at the inhalation port. Consequently, the negative pressure creates a force that pulls on the valve face  507  of the valve  505 . However, the valve  505  and the valve face  507  are also biased by the spring  502  (via the post  508  and spring seat  501 ) toward a closed position, and therefore, remain closed until the pressure threshold required to open the valve  505  is reached. As a user continues to inhale, or inhale with greater strength, the negative pressure created at the inhalation port increases, until the pressure threshold is reached, at which point the valve face  507  is pulled away from the seat formed by the center cylinder  509  of the connector  504 , and the valve  505  opens. Once the valve  505  is opened, a user is able to inhale air surrounding the pressure threshold resistor  500  and the respiratory device, so long as the negative pressure generated at the inhalation port by the user&#39;s inhalation maintains or exceeds the threshold pressure required to open the valve  505 . If the user stops inhaling, or if the negative pressure generated by the user&#39;s inhalation drops below the threshold pressure, the biasing force of the spring  502  closes the valve  505 . 
       FIGS. 62A-B  and  63 A-B are side and cross-sectional views of the pressure threshold resistor  500 , further illustrating selective adjustment of the pressure threshold required to open the valve  505 .  FIGS. 62A and 63A  illustrate the pressure threshold resistor  500  at a “low setting,” while  FIGS. 62B and 63B  illustrate the pressure threshold resistor  500  at a “high setting.” The pressure threshold resistor  500  may be selectively adjusted between a low setting, as shown in  FIG. 62A , and a high setting, as shown in  FIG. 62B , by rotating the adjuster  503  relative to the connector  504 . As shown in  FIGS. 63A and 63B , rotation of the adjuster  503  effectively increases the compression of the spring  502 , which in turn increases the bias of the spring  502  acting on the valve  505 . Consequently, the pressure threshold required to open the valve  505  also increases. In this way, the pressure threshold is selectively adjustable by a user. 
     As previously noted, the pressure threshold resistor  500  is connectable to the inhalation port of any number of respiratory devices, including for example, the inhalation port  311  of OPEP device  300 , as shown in  FIGS. 64A-D . Operation of the OPEP device  300  with the pressure threshold resistor  500  is illustrated in  FIGS. 64C-D . In general, when a user exhales into the OPEP device  300 , the one way valve  384  remains closed due to positive exhalation pressure, forcing exhaled air along the exemplary flow path identified by dashed line in  FIG. 64C  through the OPEP device  300  for administration of OPEP therapy. On the other hand, when a user inhales, the one way valve  384  opens due to negative inhalation pressure. At the same time, the orifice of the variable nozzle  336  described above in relation to the OPEP device  300  closes due to the negative inhalation pressure. With the orifice of the variable nozzle  336  closed and the one-way valve  384  open, as the user continues to inhale, or inhale with greater strength, a negative pressure created at the inhalation port  311  increases until the pressure threshold is reached, at which point the valve  505  of the threshold pressure resistor  500  opens, allowing air surrounding the pressure threshold resistor  500  and the OPEP device  300  to flow along the exemplary flow path identified by dashed line in  FIG. 64D . 
     The pressure threshold resistor  500 , as well as the other RMT devices disclosed herein, may also be sized and shaped for use on other respiratory treatment devices. Solely by way of example,  FIGS. 65A-B  show the pressure threshold resistor  500  connected to an inhalation port an OPEP device  599  described in U.S. Pat. Nos. 6,776,159 and 7,059,324, the entireties of which are herein incorporated by reference, and commercially available under the trade name ACAPELLA® from Smiths Medical of St. Paul, Minn. The RMT devices disclosed herein may also be used with the OPEP devices described in U.S. patent application Ser. No. 13/489,894, filed on Jun. 6, 2012, now U.S. Pat. No. 9,358,417, and U.S. patent application Ser. No. 14/092,091, filed on Nov. 27, 2013, pending, the entireties of which are herein incorporated by reference. 
     Turning to  FIGS. 66A-E , side and cross-sectional views of another embodiment of a pressure threshold resistor  520  are shown. The pressure threshold resistor  520  is shaped and sized to be removably connectable to an inhalation port of a respiratory device including, for example the inhalation port  311  of OPEP device  300 . The pressure threshold resistor  520  may also be shaped and sized to be removably connectable to an exhalation port of a respiratory treatment device, including for example, as shown and described below with regard to the OPEP device  700 . The pressure threshold resistor  520  may be removabaly connectable to respiratory devices by any suitable means, including a friction fit, threaded engagement, a snap fit, or the like. In general, the pressure threshold resistor  520  includes a housing  521  comprising a first section  522  and a second section  523 , a spring seat  524 , a spring  525 , and a valve  526  having a valve face  528 . 
     The first section  522  and the second section  523  of the housing  521  are removably connected to one another by a threaded engagement. The relative positon of the first section  522  to the second section  523  may also be selectively increased or decreased by rotating the first section  522  relative to the second section  523 . As discussed below, one section of the housing  521  may be rotated relative to the other section of the housing  521  to selectively increase or decrease the threshold pressure required to open the valve  526  of the pressure threshold resistor  520 . The first section  521  also includes a valve seat  527 , while the second section  523  also includes a spring seat  524  that functions as a stop for the spring  525 . 
     The pressure threshold resistor  520  functions in a manner similar to the pressure threshold resistor  500 , except that the pressure threshold resistor  520  is configured to provide RMT upon exhalation or inhalation. As previously noted, the pressure threshold resistor  520  is connectable to an exhalation port of any number of respiratory devices. To provide RMT upon exhalation, the first section  522  of the pressure threshold resistor  520  is connected to an exhalation port of a respiratory device. 
     As shown in  FIG. 66B , when a user exhales into a respiratory device such that a positive exhalation pressure is created at an exhalation port of the respiratory device, the positive pressure creates a force that pushed on the valve face  528  of the valve  526 . However, the valve  526  and the valve face  528  are also biased by the spring  525  toward a closed position, and therefore, remain closed until the pressure threshold required to open the valve  526  is reached. As a user continues to exhale, or exhale with greater strength, the positive pressure created at the exhalation port increases, until the pressure threshold is reached, at which point the valve  526  is pushed off the valve seat  527  formed in the first section  522  of the housing  521 , and the valve  526  opens, as shown in  FIG. 66C . Once the valve  526  is opened, a user is able to exhale through the pressure threshold resistor  520  and the respiratory device, so long as the positive pressure generated at the exhalation port by the user&#39;s exhalation maintains or exceeds the threshold pressure required to open the valve  526 . If the user stops exhaling, or if the positive pressure generated by the user&#39;s exhalation drops below the threshold pressure, the biasing force of the spring  525  closes the valve  526 , as shown in  FIG. 66B . 
     The pressure threshold resistor  520  is also connectable to an inhalation port of any number of respiratory devices. To provide RMT upon inhalation, the second section  523  of the pressure threshold resistor  520  is connected to the inhalation port of a respiratory device. As shown in  FIG. 66D , when a user inhales into a respiratory device such that a negative inhalation pressure is created at an inhalation port of the respiratory device, the negative pressure creates a force that pulls on the valve  526 . However, the valve  526  is also biased by the spring  525  toward a closed position, and therefore, remain closed until the pressure threshold required to open the valve  526  is reached. As a user continues to inhale, or inhale with greater strength, the negative pressure created at the inhalation port increases, until the pressure threshold is reached, at which point the valve  526  is pulled off the valve seat  527  formed in the first section  522  of the housing  521 , and the valve  526  opens, as shown in  FIG. 66E . Once the valve  526  is opened, a user is able to inhale air surrounding the respiratory device through the pressure threshold resistor  526  and the respiratory device, so long as the negative pressure generated at the inhalation port by the user&#39;s inhalation maintains or exceeds the threshold pressure required to open the valve  526 . If the user stops inhaling, or if the negative pressure generated by the user&#39;s inhalation drops below the threshold pressure, the biasing force of the spring  525  closes the valve  526 , as shown in  FIG. 66D . 
       FIGS. 67A-B  and  68 A-B are side and cross-sectional views of the pressure threshold resistor  520 , further illustrating selective adjustment of the pressure threshold required to open the valve  526 .  FIGS. 67A and 68A  illustrate the pressure threshold resistor  520  at a “high setting,” while  FIGS. 67B and 68B  illustrate the pressure threshold resistor  520  at a “low setting,” The pressure threshold resistor  500  may be selectively adjusted between a high setting, as shown in  FIG. 67A , and a low setting, as shown in  FIG. 67B , by rotating the first section  522  of the housing  521  relative to the second section  523  of the housing  521 . As shown in  FIGS. 68A and 68B , rotation of the first section  522  of the housing  521  relative to the second section  523  of the housing  521  effectively decreases the compression of the spring  525 , which in turn decreases the bias of the spring  525  acting on the valve  526 . Consequently, the pressure threshold required to open the valve  526  also decreases. In this way, the pressure threshold is selectively adjustable by a user. 
     Flow Resistors 
     Turning to  FIGS. 69A-E , a perspective and cross-sectional views of a flow resistor  550  are shown. As with the pressure threshold resistor  520 , the flow resistor  550  may be shaped and size to be removably connectable to the inhalation port or the exhalation port of any number of respiratory devices, including, for example, the inhalation port  311  of the OPEP device  300 . The flow resistor  550  may be removabaly connectable to respiratory devices by any suitable means, including a friction fit, threaded engagement, a snap fit, or the like. 
     In general, the flow resistor  550  includes a housing  551  having a first section  552  and a second section  553 , a one-way valve  554 , and at least one orifice  555 . The first section  552  of the housing  551  is connectable to the respiratory device. The one-way valve  554  is positioned in the first section  552  of the housing  551 . If the flow resistor  550  is to be used during inhalation, as shown in  FIGS. 69B-C , the one-way valve  554  may be positioned to open upon inhalation toward the first section  552  of the housing  551 . If the flow resistor  550  is to be used during exhalation, as shown in  FIGS. 69D-E , the one-way valve  554  may be positioned to open upon exhalation toward the second section  553  of the housing  551 . One or more orifices  555  are formed in the first section  552  of the housing  551 . 
     The first section  552  of the housing  551  is removably connected to the second section  553  of the housing  551  via a threaded engagement. The positon of the first section  552  relative to the second section  553  may be selectively increased or decreased by rotating the first section  552  relative to the second section  553 . As discussed below, one section of the housing  551  may be rotated relative to the other section of the housing  551  to selectively increase or decrease the resistance to the flow of air through the flow resistor  550 . 
     In operation the flow resistor  550  restricts the flow of air through the orifice(s)  555  of the flow resistor  550 . As shown in  FIG. 69B , during inhalation, a negative pressure is generated in the first section  552  of the housing  551 , causing the one-way valve  554  to open toward the first section  552 , and permitting air surrounding the flow resistor  550  and the attached respiratory device through the one or more orifices  555 . Restriction of the flow of air through the flow restrictor  550 , and therefore the attached respiratory device, results in a greater negative inhalation pressure within the attached respiratory device. As shown in  FIG. 69C , the flow resistor  550  may be selectively adjusted to increase or decrease the restriction on the flow of air through the one or more orifices  550 , and therefore the negative inhalation pressure in the attached respiratory device, by rotating the first section  552  of the housing  551  relative to the second section  553  of the housing  551 , thereby causing the cross-sectional area of the orifice(s)  550  to gradually increase or decrease. In  FIG. 69B , the flow resistor  550  is configured for low air flow and high inhalation pressure. In  FIG. 69C , the flow resistor  550  is configured for high air flow and low inhalation pressure. 
     As shown in  FIG. 69D , during exhalation, a positive pressure is generated in the first section  552  of the housing  551 , causing the one-way valve  554  to open toward the second section  553 , and permitting air in the attached respiratory device to flow through the flow resistor  550  and out the one or more orifices  555 . Restriction of the flow of air through the flow restrictor  550 , and therefore the attached respiratory device, results in a greater positive exhalation pressure within the attached respiratory device. As shown in  FIG. 69E , the flow resistor  550  may be selectively adjusted to increase or decrease the restriction on the flow of air through the one or more orifices  555 , and therefore the positive exhalation pressure in the attached respiratory device, by rotating the first section  552  of the housing  551  relative to the second section  553  of the housing  551 , thereby causing the cross-sectional area of the orifice(s)  555  to gradually increase or decrease. In  FIG. 69D , the flow resistor  550  is configured for low air flow and high exhalation pressure. In  FIG. 69E , the flow resistor  550  is configured for high air flow and low exhalation pressure. 
     Turning to  FIGS. 70A-C , perspective, cross-sectional, and front views of another embodiment of a flow resistor  570  are shown. In general, the flow resistor  570  includes a housing  571  having a first section  576  and a second section  577 , a one-way valve  572 , a restrictor plate  573 , and an adjustment ring  574 . The housing  571  is generally tubular. The one way valve  572 , like the one-way valve  384 , includes a flap configured to open in response to negative or positive pressure, depending on the direction of air flow. The one way valve  572  is different than the one-way valve  384  in that the flap is shaped and sized to cover only a portion of the internal cross-sectional area of the tubular housing  571 . As shown, the flap may be shaped as a semi-circle. The restrictor plate  573  is positioned in the housing  571  adjacent the one-way valve  572  and is shaped and sized to cover only a portion of the internal cross-sectional area of the tubular housing  571 . As shown, the restrictor plate  573  may also be shaped as a semi-circle. The restrictor plate  573  is connected to the adjustment ring  574 , both of which may be selectively rotated relative to the housing  571 . In this way, the adjustment ring  574  and the restrictor plate  573  may be rotated relative to the housing  571  to increase or decrease the cross sectional area of an orifice  575  formed in the tubular housing  571 . In the embodiment shown in  FIGS. 70B-C , because the one way valve  572  and the restrictor plate  573  are both shaped as semi-circles, the cross-sectional area of the orifice  575  may be selectively adjusted from a low setting, where the one-way valve  572  and the restrictor plate  573  are fully aligned, leaving a semi-circular orifice  575 , to a high setting, where the one-way valve  572  and the restrictor plate  573  are opposite one another, completely covering the internal cross-sectional area of the tubular housing  571 , and therefore altogether closing the orifice  575 . 
     Like the flow resistor  550 , the flow resistor  570  may be connected to an inhalation port or an exhalation port of a respiratory device, including for example, the inhalation port  311  of the OPEP device  300 . The flow resistor  570  may be removabaly connectable to respiratory devices by any suitable means, including a friction fit, threaded engagement, a snap fit, or the like. The first section  576  of the housing  571  may be connected to an inhalation port of a respiratory device, whereas the second section  577  of the housing  571  may be connected to an exhalation port of a respiratory device. The flow resistor  570  otherwise operates in the same manner as described above with regard to the flow resistor  550 . 
     The flow resistor  570  differs from the flow resistor  550 , however, in that it may also be attached to the mouthpiece or inlet of a respiratory treatment device, including for example, the OPEP device  300 , as shown in  FIG. 71 . Because the flow resistor  550  may be selectively adjusted to maintain an orifice  575  unobstructed by the one-way valve  572  or the restrictor plate  573 , the flow resistor  550  may be used at the mouthpiece or inlet of a respiratory treatment device to perform RMT upon both inhalation or exhalation. If, however, the flow resistor  550  is selectively adjusted such that the one-way valve  572  and the restrictor plate  573  are opposite one another, completely covering the cross-sectional area of the tubular housing  571 , thereby eliminating the orifice  575 , exhalation may be entirely prevented, thus preventing use of the attached respiratory device. 
     Combined RMT and OPEP Embodiment 
     Turning to  FIGS. 72A-C ,  73 A-F, and  74 A-E, a combined RMT and OPEP device  600  is shown.  FIGS. 72A-C  are perspective, front, and side views of the device  600 .  FIGS. 73A-F  are full and partial cross-sectional views of the device  600 , illustrating combined administration of RMT and OPEP therapy during exhalation.  FIGS. 74A-E  are full and partial cross-sectional views of the device  600 , illustrating combined administration of RMT and OPEP therapy during inhalation. 
     The device  600  is similar to the OPEP device  400  in that the device  600  is configured to administer OPEP therapy upon both exhalation and inhalation. While the shape and configuration of the device  600  differs from that of the OPEP device  400 , the general components for performing OPEP therapy are otherwise the same. The device  600 , however, substitutes the one-way exhalation valve  490  in in the OPEP device  400  with a pressure threshold resistor  520 A configured to provide RMT upon exhalation, and substitutes the one-way inhalation valve  484  with a pressure threshold resistor  520 B configured to provide RMT upon inhalation. Alternatively, the pressure threshold resistors  520 A and  520 B may be replaced with flow resistors, such as for example, the flow resistor  550 . 
     Like the OPEP device  400 , the device  600  includes a housing  602  including a first opening  612  (a mouthpiece), a second opening  613  (an exhalation port), and a third opening  615  (an inhalation port). Although the first opening  612  is shown as a mouthpiece, the first opening  612  may alternatively be associated with other user interfaces, for example, a gas mask or a breathing tube. As stated above, a pressure threshold resistor  520 A is connected to the device  600  at the second opening  613  (an exhalation port) to provide RMT upon exhalation at the first opening  612 , while a pressure threshold resistor  520 B is connected to the device  600  at the third opening  615  (an inhalation port) to provide RMT upon inhalation at the first opening  612 . 
     The device  600  further includes a manifold plate  693  having an exhalation passage  694  and an inhalation passage  695 . A one-way valve  691  is adapted to mount within the manifold plated  693  adjacent to the exhalation passage  694  such that the one-way valve opens in response to air exhaled into the first opening  612 , and closes in response to air inhaled through the first opening  612 . A separate one-way valve  692  is adapted to mount within the manifold plate  693  adjacent to the inhalation passage  695  such that the one-way valve  692  closes in response to air exhaled into the first opening  612 , and opens in response to air inhaled through the first opening  612 . Although the one-way valve  691  and one-way valve  692  are shown as separate components, it should be appreciated that they could be designed as a single part with two flaps adapted to fit within the manifold plate  693 . 
     The device  600  further includes a restrictor member  630  and a vane  632  operatively connected by a shaft  634 , the assembly of which may operate in the same manner as described above with regard to the previously disclosed OPEP devices, as well as a variable nozzle  636 . The device also includes a plurality of chambers. Air transmitted through the first opening  612  of the housing  602 , whether inhaled or exhaled, traverses a flow path that passes, at least in part, past the restrictor member  630  housed in a first chamber  614 , and through a second chamber  618  which houses the vane  632  operatively connected to the restrictor member  630 . In this regard, at least a portion of the flow path for both air exhaled into or inhaled from the first opening  612  is overlapping, and occurs in the same direction. 
     Turning to  FIGS. 73A-F , operation of the device  600  will now be described during a period of exhalation. As a user exhales into the first opening  612 , exhaled air enters a diverter chamber  638 . In the diverter chamber  638 , a positive exhalation pressure generated by the exhaled air maintains the one-way valve  692  in a closed position, while forcing the one-way valve  691  open, allowing exhaled air to enter a third chamber  640 . The third chamber  640  is in fluid communication with the third opening  615  (an inhalation port), and via an opening  642 , the first chamber  614 . In the third chamber  640 , exhaled air is forced to flow through the opening  642  into the first chamber  614 , since the pressure threshold resistor  520 B is inserted in the third opening  615  and configured to provide RMT on inhalation. As the exhaled air flows through the first chamber  614 , past the restrictor member  630 , through the variable nozzle  636 , and past the vane  632  in the second chamber  618 , rotation of the vane  632  causes rotation of the restrictor member  630  for administration of OPEP therapy, as described above with regard to the previously described OPEP devices. 
     Exhaled air then exits the second chamber  618  through a pair of openings  644  and flows into a forth chamber  646 , which is also in fluid communication with a fifth chamber  648  via an opening  650 . The fifth chamber itself is in fluid communication with the one-way valve  629  and the pressure threshold resistor  520 A connected to the device  600  via the second opening  613  (an exhalation port). At this point, the positive exhalation pressure in the diverter chamber  638  is greater than the positive exhalation pressure in the fifth chamber  648 , keeping the one-way valve  692  closed, and preventing exhaled air from re-entering the diverter chamber  638 . As such, the exhaled air in the fifth chamber  648  is forced to exit the device  600  through the second opening  613  and the pressure threshold resistor  520 A for the administration of RMT. 
     Turning to  FIGS. 74A-F , operation of the device  600  will now be described during a period of inhalation. As a user inhales through the device  600  through the first opening  612 , a negative inhalation pressure is generated in the diverter chamber  638 , maintaining the one-way valve  691  in a closed position, while pulling the one-way valve  692  open. As a user continues to inhale with the one-way valve  692  open, a negative inhalation pressure is generated in the fifth chamber  648 . The fifth chamber is in fluid communication with the pressure threshold resistor  520 A connected to the device  600  via the second opening  613  (exhalation port) and the forth chamber  646  via opening  650 . Since the pressure threshold resistor  520 A is configured for administration of RMT on exhalation, the negative inhalation pressure is transmitted to the forth chamber  646  via the opening  650 , and consequently, the second chamber  618 . The negative inhalation pressure in the second chamber  618  draws open the variable nozzle  636 , thereby transmitting the negative pressure to the first chamber  614 , past the restrictor member  630 , and into the third chamber  640  via the opening  642 . The third chamber  640  is in fluid communication with the one-way valve  691  and the pressure threshold resistor  520 B. At this point, the negative exhalation pressure in the diverter chamber  638  is greater than the negative exhalation pressure in the third chamber  640 , keeping the one-way valve  691  closed, and preventing inhaled air from re-entering the diverter chamber  638 . As such, the negative inhalation pressure in third chamber  640  is forced to draw air into the device  600  through the third opening  615  and the pressure threshold resistor  520 B for the administration of RMT. 
     As a user continues to inhale and the pressure threshold is reached, air flows through the pressure threshold resistor  520 B and into the device  600 , along the follow inhalation flow path: inhaled air first flows into the third chamber  640 , then through the opening  642  into the first chamber  614 , past the restrictor member  630 , through the variable nozzle  636  into the second chamber  618 , past the vane  632 , into the forth chamber  646 , through the opening  650  into the fifth chamber  648 , through the inhalation passage  695  into the diverter chamber  638 , then out the first opening  612 . As inhaled air flows through the first chamber  614 , past the restrictor member  630 , through the variable nozzle  636 , and through the second chamber  618 , past the vane  632 , rotation of the vane  632  causes rotation of the restrictor member  630  for administration of OPEP therapy, as described above with regard to the previously described OPEP devices. In this way, the device  600  provides RMT and OPEP therapy during both inhalation and exhalation. 
     The foregoing description has been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the inventions to the precise forms disclosed. It will be apparent to those skilled in the art that the present inventions are susceptible of many variations and modifications coming within the scope of the following claims.