Exhalation scavenging therapy mask

A respiratory mask for a medical patient including a shell and a flow coupling is disclosed. The shell includes an upper portion configured to cover a nose of the patient and a lower portion configured to cover a mouth of the patient, where an internal surface of the shell defines an interior volume of the respiratory mask. The flow coupling includes a body, a supply flow passage extending through the flow coupling, a scavenging flow passage extending through the flow coupling, and a septum within the body that separates the supply flow passage from the scavenging flow passage. The supply flow passage and the scavenging flow passage are fluidly coupled to an aperture that extends through the upper portion of the shell, and an aperture extending through the lower portion of the shell, respectively.

FIELD OF THE INVENTION

The present invention relates generally to a gas delivery and scavenging device for use in the medical field. More particularly, the present invention relates to a mask for delivering therapeutic gases to medical patients and scavenging exhaled gases from medical patients.

BACKGROUND

Therapeutic gases, including oxygen, anesthetic agents, and the like, are commonly administered to medical patients during treatment. The therapeutic gases may be administered to the patient through a mask that covers the patient's nose and mouth.

Some therapeutic gases pose well-known health risks to medical workers and patients. For example, medical workers exposed to anesthesia could lose consciousness or die as a result of the exposure. Further, even small amounts of anesthesia inhaled by medical workers could diminish their capacity to provide competent care to patients, thereby jeopardizing the safety of the patients under their care.

Patients may continue to exhale residual therapeutic gases even after delivery of the therapeutic gases has ended. In turn, the residual gases exhaled may be of sufficient quantity to pose the aforementioned risks to the safety of medical workers and other patients if not properly scavenged. Thus, there exists a need for scavenging and control of therapeutic gases exhaled by medical patients.

U.S. Pat. No. 6,357,437 (“the '437 patent”) describes a pliable medical mask with an oxygen port and a recovery port extending through an upper portion of the mask. The recovery port in the '437 patent is attached to an evacuation assembly including openings that are in fluid communication with the surrounding area. The '437 patent states that the channels through the evacuation assembly allow waste gases to leak into the surrounding area. Further, the oxygen port and the recovery port in the '437 patent are free to pivot at their respective mask attachment points, given their independent arrangement and the flexible nature of the mask shell, thereby making it difficult to maintain effective relative positioning between the ports within the mask.

U.S. Pat. No. 7,114,498 (“the '498 patent”) describes a medical face mask including a shell that is fabricated of a flexible material, and a fresh-gas inflow tube and an exhaust-gas outflow tube, both of which are connected to an upper nasal portion of the mask. However, clinical use of such a mask has revealed that typical central vacuum systems may not provide sufficient scavenging potential to prevent leakage of exhaled gases from the mask into the surrounding area.

Accordingly, there exists a need for an improved mask that delivers therapeutic gases to medical patients and scavenges exhaled gases away from the surrounding area.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by embodiments of the present invention that provide a respiratory mask for a medical patient for delivering therapeutic gases to the patient and scavenging exhaled gases away from the patient and the surrounding area.

In accordance with one embodiment of the present invention, a respiratory mask for a medical patient comprises a shell and a flow coupling. The shell includes an upper portion configured to cover a nose of the patient and a lower portion configured to cover a mouth of the patient, where an internal surface of the shell defines an interior volume of the mask. The flow coupling includes a body, a supply flow passage extending through the flow coupling, a scavenging flow passage extending through the flow coupling, and a septum within the body that separates the supply flow passage from the scavenging flow passage. The supply flow passage is fluidly coupled to a first aperture that extends through the upper portion of the shell, and the scavenging flow passage is fluidly coupled to a second aperture that extends through the lower portion of the shell.

In accordance with another embodiment of the present invention, a respiratory mask for a medical patient comprises a shell and a flow coupling. The shell includes a base that defines a peripheral edge, a lower portion having a top, a bottom, and a maximum depth extending from the base, and an upper portion disposed above the lower portion. The upper portion includes an overhanging surface that extends from the top of the lower portion in a direction away from the base, where the overhanging portion extends away from the base beyond the maximum depth of the lower portion. An interior volume of the mask is defined by an internal surface of the shell. The flow coupling includes a body, a supply flow passage extending through the flow coupling, a scavenging flow passage extending through the flow coupling, and a septum within the body that separates the supply flow passage from the scavenging flow passage. The supply flow passage is fluidly coupled to a first aperture that extends through the upper portion of the shell, and the scavenging flow passage is fluidly coupled to a second aperture that extends through the lower portion of the shell.

In accordance with yet another embodiment of the present invention, a flow coupling for a respiratory mask comprises a body, a supply flow passage disposed through the flow coupling, a scavenging flow passage disposed through the flow coupling, a septum within the body that separates the supply flow passage from the scavenging flow passage; and a first extension tube extending from a first end of the body and including a first lumen therein. The first lumen is in fluid communication with the supply flow passage and an aperture disposed at a distal end of the first extension tube.

A respiratory mask according to embodiments of the present invention may be used to deliver a therapeutic gas to a wearer of the mask. Further, a respiratory mask according to embodiments of the present invention may be used to scavenge gases away from a wearer of the mask. Moreover, a respiratory mask according to the present invention may be used to sample gases for analysis.

As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the present invention. It is understood, therefore, that the claims include such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

DETAILED DESCRIPTION

Embodiments of the invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout.

Referring now toFIGS. 1 and 2, it will be appreciated thatFIG. 1is a perspective view illustrating a respiratory mask10for a medical patient according to an embodiment of the invention, andFIG. 2is a front view illustrating a respiratory mask10for a medical patient according to another embodiment of the invention.

The respiratory mask10includes a shell12and a flow coupling14. The mask10has a base15that is configured to engage the face of a medical patient, and that defines a peripheral edge16. The base15may include a nose engaging portion18that is configured to engage the bridge of the patient's nose. Further the base15may include a chin engaging portion20and cheek engaging portions22that are configured to engage the contours of a patient's chin and cheeks, respectively. A deformable strip24may attach to an outer surface26of the shell12, where the deformable strip may aid in shaping the shell12around the contour of the patient's nose. The shell12may also include attachment points28for attaching a retaining strap (not shown), such as an elastic strap, for example, to the shell12.

The flow coupling14has a supply flow inlet port30, whereby a supply of therapeutic gases enters the flow coupling14. The therapeutic gases delivered to the respiratory mask10through the flow coupling14may include air, oxygen, anesthetic agents, combinations thereof, or other therapeutic gases known to persons of ordinary skill in the art. Further, the flow coupling14has a scavenging flow outlet port32, whereby scavenged gases exit the flow coupling. A corrugated extension tube34may be attached to the scavenging flow outlet port32, where the corrugated structure of the tube provides compliance in bending with simultaneous compressive hoop strength to resist sub-atmospheric pressures within the corrugated extension tube34.

The shell12may include one or more check valves36disposed in valve apertures38through the shell12. The check valves36allow gas to flow from the local environment40into the interior of the shell12via the valve apertures38when the pressure within the interior of the shell12is sufficiently lower than a pressure of the local environment40. Else, the check valves restrict or seal gases from flowing from the interior of the shell12to the local environment40via the valve apertures38when the pressure within the interior of the shell is not sufficiently lower than a pressure of the local environment40. The check valves36allow a patient to draw in air from the local environment40in the event that gas supply to the supply flow inlet port30is insufficient.

FIG. 3is a cross-sectional view taken along section3-3of the shell12inFIG. 2. The shell12includes an upper portion42that is configured to cover a nose of the patient and a lower portion44that is configured to cover a mouth of the patient. The upper portion42may have a nose-like profile in the xz-plane, as illustrated inFIG. 3. The lower portion44has a top44aand a bottom44b, and extends a maximum depth45from the base15of the shell12in the x-direction.

An interior surface46of the shell12defines an interior volume48of the mask, where the interior surface46of the shell12is opposite the outer surface26of the shell12. The interior surface46of the shell12spans both the upper portion42of the shell12and the lower portion44of the shell12, such that both the upper portion42and the lower portion44contribute to defining the interior volume48.

The upper portion42of the shell12defines an inlet aperture50therethrough, whereby therapeutic gases may enter the interior volume48of the shell12according to flow arrow54. Further, the lower portion44of the shell12defines an exit aperture52therethrough, whereby gases exhaled by the patient may exit the interior volume48of the shell12according to flow arrow56.

In one embodiment of the present invention, the upper portion42of the shell12includes an overhanging portion58. The overhanging portion58projects away from the peripheral edge16of the shell12in the x-direction above the lower portion44, such that the lower portion44is disposed below the overhanging portion58in the z-direction. Further, the lower portion44may project away from the overhanging portion58in the z-direction. In another embodiment of the present invention, a portion of the shell12between the overhanging portion58and the lower portion44demarcates the boundary between the upper portion42and the lower portion44of the shell12. Throughout the present disclosure, each of the x-direction, y-direction, and z-direction are orthogonal to one another.

In one embodiment of the present invention, the inlet aperture50through the shell12is defined by the overhanging portion58. In such an embodiment, a line60normal to a plane lying in the exit aperture52may intersect a line62normal to a plane lying in the inlet aperture50.

The exit aperture52may be disposed through the shell12at a location that advantageously locates an axis60of the exit aperture52below the mouth of a wearer of the mask10. Alternatively, the exit aperture52may be disposed through the shell12at a location that advantageously locates the entire exit aperture52below the mouth of a wearer of the mask10.

In an embodiment of the present invention, a vertical distance47along that z-direction between the top44aand the bottom44bof the lower portion44advantageously ranges from about 1.7 inches to about 2.7 inches. In another embodiment with a different configuration, the vertical distance47advantageously ranges from about 1.95 inches to about 2.45 inches. In yet another advantageous embodiment, the vertical distance47is about 2.2 inches.

In an embodiment of the present invention, a vertical distance49along the z-direction from the bottom44bof the lower portion44to the line60through the exit aperture52of the shell12advantageously ranges from about 1.35 inches to about 1.85 inches. In another embodiment with a different configuration, the vertical distance49advantageously ranges from about 1.1 inches to about 2.1 inches. In yet another advantageous embodiment, the vertical distance49is about 1.6 inches.

FIG. 4is a cross-sectional view taken along section3-3of the respiratory mask10for a medical patient inFIG. 2. The respiratory mask10includes a shell12and a flow coupling14. The flow coupling may include a body64with an elongated monolithic shape, which may include a generalized cylindrical shape. The body64may have a circular cross section, a polygonal cross section, an oval cross section, or the like.

The body64has a first shell engagement portion66that engages the shell12, such that the supply flow inlet port30is fluidly coupled to the interior volume48of the shell12through a supply flow outlet port68. The first shell engagement portion66may be an external surface of the body64. In an advantageous embodiment of the present invention, the supply flow outlet port68is disposed in a portion of the interior volume48of the shell12that is defined by the upper portion42of the shell12. In yet another advantageous embodiment of the present invention the shell12seals around the first shell engagement portion66of the flow coupling14.

The body64has a second shell engagement portion70that engages the shell12, such that the scavenging flow outlet port32of the body64is fluidly coupled to the interior volume48of the shell12through a scavenging flow inlet port72, best shown inFIG. 5. In an advantageous embodiment of the present invention, scavenging flow inlet port72(seeFIG. 5) is disposed in a portion of the interior volume48of the shell12that is defined by the lower portion44of the shell12. In another advantageous embodiment of the present invention, the shell12seals around the second shell engagement portion70of the flow coupling14.

Referring now toFIGS. 5 and 6, it will be appreciated thatFIG. 5is a rear view illustrating a flow coupling for a respiratory mask10according to an embodiment of the invention, and thatFIG. 6is a cross-sectional view taken along section6-6of the respiratory mask10for a medical patient inFIG. 5.

The body64defines a supply flow passage74therein. The supply flow passage74of the body64is in fluid communication with both the supply flow inlet port30and the supply flow outlet port68. Further, the body64defines a scavenging flow passage76therein. The scavenging flow passage76is in fluid communication with both the scavenging flow inlet port72and the scavenging flow outlet port32. The flow coupling14may include a gas sampling port84, through which scavenged gases may be sampled for analysis, that is in fluid communication with the scavenging flow passage76. In one embodiment the sampled gases are analyzed to determine the patient's end tidal CO2concentration.

In an advantageous embodiment of the present invention, the supply flow passage74is separated from the scavenging flow passage76by a septum78disposed within the body64. The septum78may be configured to isolate the supply flow passage74from the scavenging flow passage76, such that the supply flow passage74is not in fluid communication with the scavenging flow passage76within the body64of the flow coupling14.

The flow coupling14may include one or more extension tubes80that projects from an end of the body64. The extension tube80defines a lumen82therein such that the lumen82is in fluid communication with both the supply flow passage74and the supply flow outlet port68. The extension tube80may include a straight cylindrical tube, a plurality of straight cylindrical tubes joined via miter joints, a curved shape, a toroidal shape, or the like. It will be appreciated that the term cylindrical, as used herein, includes generalized cylindrical shapes, which may have any cross section, not limited to a circular cross section.

Alternatively, the flow coupling14may not include any extension tubes projecting from the end of the body64. In such a configuration without an extension tube, the supply flow outlet port68may be defined by an aperture through the end of the flow coupling14.

Applicants have discovered advantageous relationships between the velocity of therapeutic gases exiting the supply flow outlet port68and scavenging performance of the respiratory mask10by promoting beneficial interaction between a jet of therapeutic gases exiting the supply flow outlet port68and the patient's nose. In one embodiment of the present invention, an internal flow area of the lumen82between about 0.06 square inches and about 0.07 square inches effects an advantageous velocity of therapeutic gases exiting the supply flow outlet port68. In another embodiment of the present invention, an internal diameter of the lumen82between about 0.28 inches and about 0.30 inches effects an advantageous velocity of therapeutic gases exiting the supply flow outlet port68.

In the non-limiting embodiment illustrated inFIG. 6, the extension tube80defines a sector of a toroidal surface. In one advantageous embodiment, the sector of the toroidal surface extends over a sector angle86ranging from about 39 degrees to about 59 degrees. In another advantageous embodiment, corresponding to a different configuration of the respiratory mask10, the sector of the toroidal surface extends over a sector angle86ranging from about 44 degrees to about 54 degrees. In yet another advantageous embodiment, the sector of the toroidal surface may have a radius of curvature88, with respect to a centerline90of the lumen82, that ranges from about 0.3 inches to about 0.4 inches.

As best shown inFIG. 6, a direction of flow92leaving the supply flow outlet port68forms an angle94with a longitudinal axis96of the body64. Applicants have discovered advantageous relationships between the supply flow outlet angle94and scavenging performance of the respiratory mask10by promoting beneficial interaction between a jet of therapeutic gases exiting the supply flow outlet port68and the patient's nose. In one embodiment, the angle94is between about 45 degrees and about 75 degrees to advantageously align the direction of flow92leaving the supply flow outlet port68with a direction of flow entering the patients nose. In another embodiment corresponding to a different configuration of the mask10, the angle94is between about 55 degrees and about 70 degrees to advantageously align the direction of flow92leaving the supply flow outlet port68with a direction of flow entering the patients nose.

In an advantageous embodiment of the present invention, an axis98of the scavenging flow inlet port72is substantially perpendicular to the longitudinal axis96of the body64. In another advantageous embodiment of the present invention, an axis100of the supply flow inlet port30is substantially perpendicular to the longitudinal axis96of the body64.

In an embodiment of the present invention, a vertical distance101from the axis98of the scavenging flow inlet port72to the supply flow outlet port68advantageously ranges from about 0.55 inches to about 2.55 inches. In another embodiment with another configuration, the vertical distance101advantageously ranges from about 1.05 inches to about 2.05 inches. In yet another advantageous embodiment of the present invention, the vertical distance101is about 1.6 inches.

As best shown inFIG. 5, the flow coupling14may include two extension tubes,80and102, where the extension tube102also projects from an end of the body64, similar to extension tube80. The extension tube102defines a lumen104therein such that the lumen104is in fluid communication with both the supply flow passage74and a supply flow outlet port106. The extension tube102may include a straight cylindrical tube, a plurality of straight cylindrical tubes joined via miter joints, a curved shape, a toroidal shape, or the like. The dimensions and flow path of the lumen104may be the same as or different from the dimensions and flow path of the lumen82.

The supply flow passage may include a lumen108located upstream of the extension tube80in a direction of supply flow, such that a cross sectional area of the lumen82transverse to a bulk flow direction through the lumen82is smaller than a cross sectional area of the lumen108transverse to a bulk flow direction through the lumen108.

As best shown inFIG. 5, the flow coupling14may include at least one flow channel partition110disposed within the scavenging flow passage76(seeFIG. 6). The at least one flow channel partition110may have a plate structure extending across the scavenging flow passage76. In an advantageous embodiment of the present invention, the at least one flow channel partition110may include two flow channel partitions oriented perpendicular to one another.

The scavenging flow inlet port72may have an internal flow area, normal to a direction of bulk flow, that advantageously ranges from about 0.1 square inches to about 0.8 square inches. Alternatively, the scavenging flow inlet port72may have an internal diameter that ranges from about 0.3 (10 mm) inches to about 1.0 inches (25 mm).

As best shown inFIG. 8, the at least one flow channel partition110may extend beyond the scavenging flow inlet port72, thereby avoiding suction lock between the scavenging flow inlet port72and a face of the wearer of the mask10. Suction lock between the scavenging flow inlet port72and the face of the wearer of the mask10is disadvantageous because it could block or unduly limit scavenging flow out of the mask10and into the suction source.

Referring toFIG. 6, the at least one flow channel partition110may advantageously extend beyond the scavenging flow inlet port72by a horizontal distance111in the x-direction that ranges from about 0.03 inches to about 0.43 inches. In another embodiment of the present invention with a different configuration, the horizontal distance111advantageously ranges from about 0.13 inches to about 0.33 inches. In yet another advantageous embodiment of the present invention, the horizontal distance111is about 0.23 inches.

The flow coupling14may be fabricated from a substantially rigid material such as, a plastic including, for example, acrylic, polyethylene, polymide, polyamide, or polyvinyl chloride; metals including, for example, aluminum; combinations thereof, or other similar materials known to persons of ordinary skill in the art.

FIG. 7is a perspective view illustrating system700for a respiratory mask10for a medical patient according to another embodiment of the invention. The respiratory mask system700includes a filter112that is fluidly coupled to the corrugated extension tube34and a suction tube extension114. In one embodiment, the corrugated extension tube34has an axial length116not less than about 24 inches to provide sufficient compliance to enable the corrugated extension tube34to be routed from the flow coupling14across the patient's body and to the filter112, without disrupting the position of the mask on the patient's face.

Further, Applicants have discovered advantageous relationships between the corrugated extension tube34axial length116and scavenging performance of the respiratory mask10, at least in part because a volume within the corrugated extension tube34provides a beneficial vacuum reservoir function. Accordingly, in other embodiments having a different configuration of the respiratory mask10, the corrugated extension tube34has an axial length116not less than about 60 inches to promote the vacuum reservoir effect of the corrugated extension tube.

In one embodiment of the present invention, the corrugated extension tube34has an internal flow area, normal to a direction of bulk flow, that advantageously ranges from about 0.12 square inches to about 1.5 square inches. In another embodiment of the present invention with a different configuration, the corrugated extension tube34has an internal flow area that advantageously ranges from about 0.4 square inches to about 0.7 square inches.

In one embodiment of the present invention, the corrugated extension tube34has an internal diameter that advantageously ranges from about 0.4 inches (10 mm) to about 1.4 inches (35 mm). In another embodiment of the present invention with a different configuration, the corrugated extension tube34has an internal diameter that advantageously ranges from about 0.7 inches (18 mm) to about 0.9 inches (24 mm).

The suction tube extension114may be coupled to a suction source (not shown) through a connector120. A clamp118may be disposed on the suction tube extension114to selectively throttle the suction pressure from the suction source or isolate the shell12from the suction source.

According to an advantageous embodiment of the present invention, the respiratory mask10is applied to the face of a medical patient and secured to the patient using an elastic strap or the like. The shell12of the respiratory mask10is positioned on the patient's face such that the nose engaging portion18rests on a bridge of the patient's nose, the chin engaging portion20rests on the patient's chin, and the cheek engaging portions22rest on the patient's cheeks. The scavenging flow passage76is fluidly coupled to a suction source via the corrugated extension tube34and optionally through the filter112and the suction tube extension114. Further, the supply flow passage74of the flow coupling14may be fluidly coupled to a supply flow source (not shown) by attaching a supply flow tube122(seeFIG. 7) to the supply flow inlet port30.

The patient inhales therapeutic gases delivered to a portion of the shell12interior volume48defined by the upper portion42of the shell12, and exhales into a portion of the shell12interior volume48defined by the lower portion44of the shell12. The location of the supply flow outlet port68in close proximity to the patient's nose within the upper portion42of the shell12, and the location of the scavenging flow inlet port72below the patient's nose and within the lower portion of the shell12, combine to effect a unidirectional bulk flow path126(seeFIG. 4) within the shell12.

Applicants have discovered that the unidirectional bulk flow path126established within the respiratory mask10reduces the dilution of incoming therapeutic gases with exhaled gases within the interior volume48of the shell12, thereby decreasing the driving potential for leakage of exhaled gases across the interface of the peripheral edge16of the shell12and the patient's face. Indeed, dilution of the incoming therapeutic gases with gases exhaled by the patient increases the flow rate of the therapeutic gases required to achieve the desired therapeutic effect. In turn, increasing the flow rate of therapeutic gases supplied to the interior volume48of the shell12increases the driving potential for leakage past the interface between the peripheral edge16of the shell12and the patient's face by increasing the pressure within the shell12.

Moreover, dilution of the incoming therapeutic gases with exhaled gases increases the amount of therapeutic gases that bypass the patient's respiratory system by flowing directly from the supply flow outlet port68to the scavenging flow inlet port72. In turn, bypass of the therapeutic gases around the patient's respiratory system increases the required scavenging flow by the suction source, not to mention wasting the bypassed therapeutic gas. Accordingly, embodiments of the present invention address the above-noted deficiencies in conventional approaches by decreasing dilution of therapeutic gases within the interior volume48of the shell12by effecting a unidirectional bulk flow path126within the interior volume48of the shell12.

Further advantageous aspects of the present invention offer improvements over conventional approaches by fixing the locations and orientations of the supply flow outlet port68and the scavenging flow inlet port72relative to one another by providing a substantially rigid flow coupling14. Thus, unlike the conventional approaches, embodiments of the present invention do not rely on the stiffness of the shell12to fix the location or orientation of the supply flow outlet port68relative to the scavenging flow inlet port72, thereby promoting careful tailoring of the bulk flow path within the respiratory mask10.

The respiratory mask10may be used to scavenge gases exhaled by a wearer of the respiratory mask10, scavenge unused therapeutic gases that bypass the respiratory system of a wearer after delivery to the respiratory mask10, or combinations thereof. In some embodiments the wearer of the respiratory mask10is a medical patient. In other embodiments the wearer of the respiratory mask10is a medical patient undergoing a surgical procedure.

In one embodiment, the gases scavenged from the respiratory mask10include air enriched with additional oxygen. In another embodiment, the gases scavenged from the respiratory mask10include oxygen and anesthetic agents.

The respiratory mask10may be used to deliver a therapeutic gas to a medical patient without scavenging. Further, the respiratory mask10may be used to scavenge gases without delivering a therapeutic gas. In one embodiment, the respiratory mask10is used to sample a gas exhaled from a medical patient for end tidal CO2analysis. In another embodiment, the respiratory mask10is used to deliver air to a medical patient and sample a gas exhaled from a medical patient for end tidal CO2analysis. In yet another embodiment, the respiratory mask10is used to deliver air, oxygen, or combinations thereof to a wearer of the respiratory mask10.