WO2017205556A1

WO2017205556A1 - Negative pressure seal for a gas therapy dressing

Info

Publication number: WO2017205556A1
Application number: PCT/US2017/034350
Authority: WO
Inventors: Lawrence J. Cali; Srinivasan Sarangapani
Original assignee: Neogenix, Llc
Priority date: 2016-05-24
Filing date: 2017-05-24
Publication date: 2017-11-30

Abstract

A dressing for delivering pressurized therapy gas to a wound. The dressing may include a negative pressure structure for creating a sealed pocket around the wound. The negative pressure structure may include a pocket (or chamber) and an aperture within the pocket. A first lumen may be fluidly connected to the aperture for delivering pressurized therapy gas to the pocket. A second lumen may be fluidly connected to the negative pressure structure for reducing pressure around the pocket and sealing the pocket around the wound. A first pump may include a first intake port fluidly connected to a first reservoir of therapy gas, as well as a first discharge port fluidly connected to the first lumen for supplying therapy gas at an increased pressure. A second pump may evacuate gas from the negative pressure structure to seal the pocket around the wound. Pressurized therapy gas may be delivered to the sealed pocket from the aperture to treat the wound.

Description

NEGATIVE PRESSURE SEAL FOR A GAS THERAPY DRESSING

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/341,065 filed on May 24, 2016, the content of which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to wound care. More particularly, this invention relates to dressings for pressurized gas therapy, which may be secured near a wound site with a negative pressure seal for the application of therapeutic gas or a mixture of gases to the wound.

BACKGROUND

Therapeutic gases may be used to treat wounds or other conditions, including acute wounds, chronic wounds, pressure ulcers, and diabetic foot ulcers. For example, a dressing may be applied to a chronic wound to form an airtight seal, and a supply of therapy gas may be connected via a tube to the dressing to blanket the wound with the therapy gas. Transdermal oxygen therapy may accelerate wound healing by various mechanisms including: energizing ischemic cells to stimulate the natural healing process and promoting the production of collagen, granulation tissue, new blood vessels and skin. Ozone (O3) therapy may be administered for the treatment of diabetic foot ulcers and other disorders. Nitric oxide (NO), carbon dioxide (CO), and hydrogen sulfide (H₂S) also may be useful for the topical treatment of wounds, conditions, or disorders. A need exists for new therapeutic gas storage and delivery devices and systems that may improve patient outcomes and expand access to patients with limited mobility or clinical support.

SUMMARY

Hence, the present disclosure is directed to a dressing for therapeutically delivering pressurized therapy gas to a wound that may include a negative pressure structure. The negative pressure structure may include a hollow annular member. The hollow annular member may include an inner surface on one side of the hollow annular member, an exterior surface on the other side of the hollow annular member, and an interior space bounded by the inner surface. The exterior surface may include a skin contact surface, and the skin contact surface may include a plurality of ports each of which may extend from the skin contact surface to the interior space. Further, the hollow annular member may include a central bore defined by the exterior surface. Additionally, the negative pressure structure may include a cover disposed over the central bore to form a sealed pocket. The cover may include a first opening extending through the cover and a fitting disposed in the first opening. The fitting may include a tubular member with a first end and a second end, the first end being in fluid communication with the pocket. The second end of the tubular member may include a second opening on the second end of the fitting, the second opening being in fluid communication with the first opening. DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals (or designations) are used to indicate like parts in the various views:

FIG. 1 presents a block diagram of a method for therapeutically applying gas to a wound;

FIG. 2 is a schematic diagram of an embodiment of an apparatus for therapeutically applying gas to a wound in accordance with the method of FIG. 1 ;

FIG. 3 is a process flow diagram of an exemplary embodiment of a therapeutic gas storage and delivery assembly for use in therapeutically applying gas to a wound;

FIG. 4 presents an exemplary embodiment of an apparatus for therapeutically delivering pressurized gas to a wound;

FIG. 5 depicts another embodiment of a mobile device for storing and therapeutically delivering pressurized gas to a wound;

FIG. 6 presents a block diagram of another exemplary method for therapeutically applying gas to a wound;

FIG. 7 is a schematic diagram of an embodiment of an apparatus for therapeutically applying gas to a wound in accordance with the method of FIG. 6;

FIG. 8 is a schematic diagram of another embodiment of an apparatus for therapeutically applying gas to a wound in accordance with the method of FIG. 6;

FIG. 9 is a process flow diagram of another embodiment of a therapeutic gas storage and delivery assembly for use in therapeutically applying gas to a wound;

FIG. 10 is a process flow diagram of yet another embodiment of a therapeutic gas storage and delivery assembly for use in therapeutically applying gas to a wound;

FIG. 11 depicts another embodiment of an apparatus for storing and therapeutically delivering pressurized gas to a wound;

FIG. 12 depicts another embodiment of an apparatus for storing and therapeutically delivering pressurized gas to a wound;

FIG. 13 depicts another embodiment of an apparatus for storing and therapeutically delivering pressurized gas to a wound;

FIG. 14 depicts another embodiment of an apparatus for storing and therapeutically delivering pressurized gas to a wound;

FIG. 15 depicts the exemplary dressing of FIG. 11 positioned about a wound site on a leg for therapeutically delivering pressurized gas to the wound;

FIG. 16 depicts the exemplary dressing of FIG. 12 positioned about a wound site on a leg for therapeutically delivering pressurized gas to the wound;

FIG. 17 is a cross-sectional view of the dressing of FIG. 15 along line 17— 17;

FIG. 18 is a cross-sectional view of the dressing of FIG. 16 along line 18— 18; FIG. 19 is a perspective view of an exemplary dressing for therapeutically delivering pressurized gas to the wound;

FIG. 20 is another perspective view of the exemplary dressing of FIG. 19;

FIG. 21 is an exploded view of the exemplary dressing of FIG. 19;

FIG. 22 is a cross-sectional view of the exemplary dressing of FIG. 19 along line 22— 22;

FIG. 23 is a cross-sectional view of the exemplary dressing of FIG. 22 along line 23— 23;

FIG. 24 is a cross-sectional view of the exemplary dressing of FIG. 22 along line 24— 24;

FIG. 25 is an exploded view of another exemplary dressing for therapeutically delivering pressurized gas to a wound;

FIG. 26 is a cross-sectional view of the exemplary dressing of FIG. 25;

FIG. 27 is a cross-sectional view of the exemplary dressing of FIG. 26 along line 27— 27;

FIG. 28 is a perspective interior view of an upper portion of another embodiment of an exemplary dressing for therapeutically delivering pressurized gas to a wound;

FIG. 29 is a cross-sectional view of an exemplary dressing formed from the upper dressing portion of FIG. 28 and the lower dressing portion of FIG. 25;

FIG. 30 is a perspective interior view of an upper portion of another embodiment of an exemplary dressing for therapeutically delivering pressurized gas to a wound;

FIG. 31 is a cross-sectional view of an exemplary dressing formed from the upper dressing portion of FIG. 30 and the lower dressing portion of FIG. 21;

FIG. 32 is a perspective interior view of an upper portion of another embodiment of an exemplary dressing for therapeutically delivering pressurized gas to a wound;

FIG. 33 is a cross-sectional view of an exemplary dressing formed from the upper dressing portion of FIG. 32 and the lower dressing portion of FIG. 21 ;

FIG. 34 is a perspective interior view of an upper portion of another embodiment of an exemplary dressing for therapeutically delivering pressurized gas to a wound;

FIG. 35 is a cross-sectional view of an exemplary dressing formed from the upper dressing portion of FIG. 34 and the lower dressing portion of FIG. 21 ;

FIG. 36 is a perspective view of an exemplary thermoformed tray and custom-matched die cut lid for packaging an exemplary kit for therapeutically applying gas to a wound;

FIG. 37 is a top view of the tray and kit of FIG. 36 with the lid removed;

FIG. 38 is a top view of another thermoformed tray and kit with the lid removed;

FIG. 39 is a top view of another thermoformed tray and kit with the lid removed;

FIG. 40 is a perspective view of another embodiment of a negative pressure seal dressing;

FIG. 41 is a cross-sectional view of the negative pressure seal dressing of FIG. 40 along line 41—41. DESCRIPTION

FIG. 1 presents a block diagram of an apparatus 10 for delivering therapeutic gas (therapy gas) to a wound 12. The apparatus 10 may include a gas storage and delivery assembly 14 for supplying the apparatus with therapy gas during wound care, a negative pressure dressing 16 for delivering therapy gas to the wound 12 being treated, and a control system 18 which may include a user interface 20 for regulating operation of the apparatus. The control system 18 may include sensors which measure operating parameters of the apparatus. The control system 18 may include a microprocessor, memory, application specific integrated circuit(s) and/or a microcontroller, as well as other semiconductor devices and electronic components. The control system may include communication capabilities. The apparatus may include a power supply. The power supply may include one or more batteries, including fixed and replaceable batteries. The fixed and replaceable batteries may be single use, rechargeable, or a combination of both types of batteries. For example, single use batteries that may be suitable for use a source of electrical power may include alkaline batteries. Preferably, alkaline batteries may be composed primarily of common metals (e.g., steel, zinc, and manganese) which may not pose a health or environmental risk during normal use or disposal. By contrast, rechargeable batteries, such as nickel cadmium, nickel metal- hydride, and lithium ion may be suitable for use as a source of electrical power. Also, mechanical devices and non-electronic electrical circuit components may be employed to regulate operation of the apparatus. Generally, the apparatus 10 may be used to heal a wound by administering therapy gas, such as oxygen, ozone, chlorine dioxide, nitrogen, nitric oxide, medical grade air, or a mixture thereof to the wound bed.

Referring to FIG. 2, the therapy gas storage and delivery assembly 14 may include a gas storage tank 22, fittings (e.g., fill valve 24 and pressure regulator 26), and flexible tubing 28 which supply the negative pressure dressing delivery system 16 with medical grade therapy gas. The tank 22 may be refillable and may be constructed of stainless steel or lined stainless steel, but other suitable configurations and materials for storing and dispensing compressed and/or liquefied gas may be used. The gas storage tank may be sized for portability and weight, as well as the desired delivery wound pressure and treatment duration. For example, the gas storage tank may be a pressure cylinder capable of supplying therapy gas continuously for 7-10 days at a service pressure of at least 5 psig. A gas storage and delivery device is disclosed in U.S. Patent

Application Ser. No. 13/457,564, entitled "Oxygen Delivery Device," filed on April 27, 2012 (the '564 application). The '564 application is incorporated herein by reference in its entirety. Although, the therapy gas may be stored in the tank 22 at a pressure of approximately 100 psig, other suitable pressure levels may be selected to achieve clinical and operational objectives.

Referring to FIG. 3, a portable therapy gas storage and delivery assembly 14 may include a

10 cm³ capacity gas cylinder (e.g., Swagelok Part #53-4CS-TN-10) 22, a shut off valve (e.g., Swagelok Part #SS-41S2) 24, a gas regulator (e.g., Beswick Engineering Part #PRD2-lNl-0- 6VK) 26, and a bleed valve (or purge valve) (e.g., Swagelok Part #SS-41S2) 30. Although not shown in FIG. 3, the bleed valve may be connected to a capture device that renders the purged gas harmless or unlikely to cause harm to human health or the environment. The fittings on the high- pressure side of the regulator may be connected by suitable metal pipe or flexible hose 32. Connection to these principal high pressure components may be made using compression fittings

(e.g., Swagelok compression fittings) 34. By contrast, the fittings on the low pressure side of the regulator 26 may be connected by flexible tubing 28 made from a polymeric material suitable for use in hospital applications. Suitable materials for use in the low pressure tubing include, but are not limited to: silicone, polyethylene, polypropylene, polyurethane and various other thermoplastics.

As shown in FIG. 9 and FIG. 10, the gas cylinder 22 may be connected to the fittings on the high pressure side of the regulator 26 by a quick connect fitting 62. In FIG. 9, the quick connect fitting 62 may be a bayonet fitting. For example, a male-bayonet fitting 64 may be disposed on the fill port of the cylinder. The male-bayonet fitting may be inserted into a female-bayonet fitting 66 that is fluidly connected to the high pressure fittings and components. Locking lugs on the male-bayonet fitting 64 may be aligned with engagement slots on the female-bayonet fitting 66. The locking lugs may be pushed into the engagement slots and twisted clockwise to lock the fitting in place. The female-bayonet fitting may be part of a housing which secures the cylinder into the portable therapy gas storage and delivery assembly 14. In FIG. 10, the quick connect fitting 62 may include a receptacle 60 that receives the cylinder. A cover 68 may mate with a portion of the receptacle 60 to lock the cylinder in the receptacle. For example, the cover 68 may be secured by a quarter turn bayonet fitting or screw threads. The gas cylinder 22 may be connected to the fittings on the high-pressure side of the regulator by a pin or fitting in the receptacle that presses against and opens a gas valve 24 on the cylinder.

Additionally, the gas storage tank 22 may be disposable. The gas storage tank may be sized for portability and weight, the desired delivery pressure near the wound site, clinical needs and/or a prescribed treatment duration. For example, the gas storage tank may be a pressure cylinder capable of supplying therapy gas continuously for 7-10 days at a service pressure of at least 1.5 psig. Although the exemplary embodiments of a therapy gas storage and delivery apparatus 14 described above preferably may include a portable gas storage tank, other sources of therapy gas may be used with the disclosed negative pressure dressing delivery system 16, including in-wall fittings and source equipment for in hospital therapy. Further, other sources of therapy gas may be adapted for use with the disclosed negative pressure dressing delivery system 16 provided that the therapy gas source is safe and reliable in providing the desired quantity and quality of therapy gas. For instance, an oxygen concentrating apparatus (e.g., ion exchange oxygen concentrator which concentrates oxygen from ambient air to a gas mixture of nearly pure oxygen) or an oxygen generating apparatus (e.g., an electrolysis device which generates oxygen from water) may be used as a source of therapy gas for the disclosed negative pressure dressing delivery system.

In use, the system 14 may be used to deliver therapy gas for wound treatment. The therapy gas may include oxygen, ozone, chlorine dioxide, nitrogen, nitric oxide, medical grade air, or a mixture thereof to the wound bed. For example, one therapy gas may be a gaseous mixture of 1%

(by mass) nitric oxide (NO) and 99% (by mass) nitrogen (N₂). In this example, nitric oxide may be considered a therapeutic agent and nitrogen may be considered a carrier gas.

Referring to FIG. 3, a prototype of the therapeutic gas and delivery assembly 14 (without bleed valve 30) was assembled and tested. The gas cylinder 22 was pressurized to 100 psig with oxygen. The pressurized prototype weighed approximately 300 grams. The regulator 26 was set to maintain an output pressure of 5 psig. The pressurized prototype was placed into operation, and the flow rate of oxygen output from the flexible tubing (or cannula) 28 was monitored. The prototype delivered a substantially constant rate of oxygen flow for approximately 20 hours. During this period, the oxygen flow rate remained steady at approximately 3.3 mL/hr. In view of these results, the gas cylinder may be charged with therapy gas to a higher pressure (e.g., up to

500 psig with the presently disclosed apparatus, or up to approximately 1000 psig with a suitable regulator, hose and fittings) to achieve continuous oxygen delivery at a similar rate for up to seven days. Alternatively, a gas cylinder with greater storage capacity may be used at a lower therapy gas output pressure. In this context, the term approximately means plus or minus 15 percent of the target value.

Accordingly, the portable therapy gas storage and delivery assembly 14 may be selectively adjusted to supply therapy gas continuously (at a constant or variable rate of flow) for up to 7-10 days at a desired regulator output pressure and/or flow rate. For example, preliminary test results indicate that a minimum pressure of 5 psig may be required to effectively kill bacteria in a chronic wound that is undergoing continuous transdermal gas therapy. In one therapeutic configuration, the regulator may be set to deliver a therapy gas at a substantially constant rate of flow (e.g., 3.3 mL/hr) while maintaining a steady output pressure of at least 5 psig for approximately 7 days. The therapy gas may be a mixture of medical grade air and nitric oxide. The nitric oxide may be 1% (by mass) of the gas mixture when measured at standard temperature and pressure. The regulator output pressure may be set to maintain a steady output pressure of approximately 5 psig.

Nevertheless, the therapeutic configuration may be modified, adjusted, or optimized based on one or more considerations or factors that may include, without limitation, the composition of the therapy gas, the altitude of the treatment location, the clinical objective of the treatment, and the efficacy of trial therapies studied in a laboratory and/or clinical setting. For example, the output pressure of the therapy gas may range from approximately 1 psig to approximately 10 psig. In this context, the term approximately means plus or minus 15 percent of the target value. Referring to FIG. 2, the therapy gas from the gas storage and delivery assembly 14 may be incorporated with a disposable, sterile wound dressing 36. The wound dressing 36 may include a therapy gas discharge structure, as well as a mechanical apparatus for securing the therapy gas discharge structure proximate to the wound. The therapy gas discharge structure may be fluidly connected to the flexible tubing (or cannula) 28 from the pressure regulator 26. The mechanical apparatus for securing the therapy gas discharge structure proximate the wound may include a negative pressure structure (or bladder) 38 and a pump 40 for evacuating air and fugitive emissions of therapy gas from the structure. The evacuated air and any fugitive emissions of therapy gas from the negative pressure structure may be treated in a capture device 74 which renders any evacuated therapy gas or wound exudate harmless or unlikely to cause harm to human health or the environment.

The mechanical pump 40 may be a miniature diaphragm pump which may be driven by a DC motor. At standard conditions, the pump may operate over a pressure range of approximately 0 kPa to 165 kPa and a vacuum range of approximately 0 mmHg to 500 mmHg. The maximum unrestricted flow of the pump may be approximately 2.5 liters per minute (LPM). Operation of the mechanical pump may be controlled via pulse width modulation of the DC motor. One commercially available pump which may be suitable for this application is a 2.5 LPM CTS Micro Diaphragm Pump manufactured by Parker Hannifin Corporation. Although a diaphragm pump may be used to evacuate gas and liquids from the negative pressure dressing delivery system 36, any suitable fluid delivery system (e.g., a spring loaded piston) may be used to evacuate the negative pressure structure (or bladder) 38 provided that the negative pressure structure securely positions the therapy gas discharge structure (e.g., the aperture) proximate the wound and creates a substantially gas tight seal between the edge of the dimple and the abutting surface (e.g., tissue, gasket material, sealant). A substantially gas tight seal in this context may be considered a seal which allows the gas storage and delivery assembly to maintain the targeted output pressure and/or flow rate in the dimple for a particular clinical application.

Referring to FIG. 4, in an exemplary embodiment the wound dressing 36 may include the discharge end of the flexible tubing 28 from the regulator 26 and the therapy gas storage tank. The flexible tubing 28 may pass through the negative pressure structure 38 to deliver the therapy gas to the wound. Penetrations 42 in the negative pressure structure 38 may be sealed. The flexible tubing 28 may be positioned directly near the wound or connected to a sealed dimple or chamber 44 within the negative pressure structure 38, which may include one or more openings (or apertures) 46 for delivering discharge therapy gas to the wound. The dimple (or chamber) 44 may be located on a skin contact surface 41, which may be a generally flat and smooth surface region of the negative pressure structure 38. In other embodiments, however, the skin contact surface may be textured or dimpled, in whole or in part, to facilitate a clinically appropriate or advantageous fit with the wound site. The skin contact surface 41 may be a flexible wall of the negative pressure structure 38. The negative pressure structure 38 further may include a number of ports 43 in the generally flat and smooth surface 41. Each port 43 may extend through the flexible wall to fluidly connect the skin contact surface with an interior space 45 (not shown) located within the negative pressure structure 38. The interior space may be bounded by the flexible wall, as well as by other walls or features of the negative pressure structure 38. The flexible wall may be formed from medical grade silicone rubber or another flexible material that is suitable for skin contact.

The interior space within the negative pressure structure 38 may be fluidly connected to a mechanical pump 40 via a conduit 50. The negative pressure structure 38 further may include quick disconnect connections 47, 49 for attaching the flexible tubing 28 and the conduit 50 to the aperture 44 and interior space 45 (not shown), respectively. The conduit may be formed from flexible tubing 28 provided the pathway for conveying gas and liquid mixtures does not collapse or otherwise occlude gas and liquid transport when subject to negative pressure supplied by the pump 40. A capture device 74 (not shown) may be fluidly connected to conduit 50 and the mechanical pump 40 as described above with respect to FIG. 2.

The wound dressing 36 further may include a gasket 48 and sealing materials (e.g., gel) which in use may be placed in direct contact with skin adjacent to the wound to create a sealed chamber about the wound. (See also, FIGS. 17 and 18). Preferably, the gasket may be sterile and may be formed from silicone. The gasket may be precut and provided in a sterile packaging. For example, the gasket may be provided in a polyethylene and Tyvek sheet. The gasket may be cut by a caregiver to fit the wound site. The silicone material may include a metal foil coating. Additionally, the gasket material 48 may include an adhesive surface to seal the gasket to the patient's skin to prevent leaks from developing between the negative pressure seal dressing 38 and the patient's skin. Additional adhesives or sealants may be used to isolate thewound site. Moreover, the gasket may include an absorbent layer on the side facing the wound. The absorbent layer may include, without limitation, polyurethane foam, hydro-colloids, hydrogels, or other absorbent materials. The negative pressure structure 38 and any gasket materials and sealants used to create the sealed cavity about the wound may be compatible with skin contact. The sealed cavity then may be filled with therapy gas to provide an atmosphere of therapy gas proximate the wound.

The negative pressure structure 38 may be shaped for a particular anatomy to help secure the dimple 44 about the wound. For example, in FIG. 4 the inflatable structure 38 may be rectangular in shape, and the therapy gas discharge site 46 may be located in the middle of the rectangular shape. As shown in FIG. 16, the negative pressure structure 38 may be draped over the wound and gas and liquid from the interior space of the negative pressure structure 38 may be evacuated to create a negative pressure seal around the wound. Using a negative pressure structure 38 to create a sealed cavity about the wound reduces compressive forces otherwise needed to confine the pressurized therapy gas to the wound area. This may reduce restriction of blood flow relative to a compressive dressing. The negative pressure structure 38 may be connected to a mechanical pump 40 via a conduit 50, such as flexible tubing 26. The pump 40 may be a hand pump, a spring- loaded piston, an electrically operated mechanical pump, or other suitable pump provided the pump draws sufficient flow to evacuate gas and liquid from the interior space and maintain negative pressure within the interior space, to achieve a sealed cavity about the wound. Components of the apparatus 10 may be contained in a housing 52 which may be secured to the wound dressing.

The wound dressing 36 may include a cuff 54 or similar garment to help position the negative pressure seal dressing to the patient. In one embodiment, the cuff 54 or another garment may wrap around the negative pressure seal dressing 36. The cuff 54 may include a pouch for receiving the 54 the negative pressure seal dressing 36. The cuff may be secured, for example, by one or more straps or a plurality of hook and latch structures (e.g., Velcro strips). The negative pressure structure 38 may include one or more tabs with an adhesive coating which may be used to secure the dressing to the patient to set or initially position the dressing with respect to the wound.

The treatment system 10 further may include a control circuit 56 for regulating operation of the gas storage and delivery assembly 14 and the negative pressure dressing delivery system 16. The treatment system 10 may include a power supply 21 for supplying electricity to the vacuum pump 40 and the control circuit 56. The control circuit may monitor process variables from the gas storage and delivery apparatus 14, the negative pressure dressing delivery system 16, the user interface 20, and the power supply 21. The control circuit 56 may include a microprocessor and memory, an application specific integrated circuit (ASIC), and/or a microcontroller 58 that is in electrical communication with other components and sensors in order to regulate operation of the treatment system 10. For example, the control circuit 56 may monitor and analyze the therapy gas flow rate as well as the vacuum level within the interior space of the negative pressure dressing to regulate operation of the mechanical pump.

Additionally, the control circuit 56 may monitor and analyze the therapy gas delivery pressure and flow rate between the pressure regulator 26 and the therapy gas discharge structure 46. Also, the control circuit 56 may monitor and analyze the fluid pressure in the negative pressure structure 38, as well as operating parameters of the vacuum pump 40. The control circuit 56 further may include a user interface 20 for powering the system on and off, as well as announcing the operational state of each process sub-assembly 14, 16. For example, the user interface 20 may include a power button and a display 20.

Referring to FIG. 5, the display 20 may provide a graphical user interface for reporting the state of process variables that may be monitored by the control circuit 56. For example, the graphical user interface may report the state of one or more of the following process variables: vacuum pump condition, negative pressure structure vacuum level, gas tank pressure, gas flow rate, treatment time, purge control, and battery charge.

As shown in FIG. 2, based on sensor data signals for monitored process variables, the control circuit 56 may regulate operation of the system 10. For example, the control circuit 56 may monitor the pressure of the negative pressure structure 38 and control operation of the vacuum pump 40 to maintain a desired vacuum level. Similarly, the control circuit 56 may monitor the pressure and discharge rate of therapy gas exiting the storage tank 22 and the pressure and discharge rate of therapy gas exiting the pressure regulator 26 to track and assess system performance. The control circuit 56 may be configured to generate audible or visual alarm based on high and low pressure measurements, differential pressure measurements, and therapy gas flow rates.

The control circuit 56 may be configured to implement prescribed functions. For example, without limitation, the control circuit 56 may be configured to report on elapsed treatment time, perform a purge of therapy gas from the wound dressing, and monitor power supply levels. Other functionality may be programmed or configured into the control circuit components as well. For example, a microcontroller may instruct the system to shut off gas flow from the storage tank 22 in the event that therapy gas is leaking from the cavity 44 at an unacceptable rate. In another example, a microcontroller may be programmed to prevent over-evacuation of fluid (gas and fluid) form the negative pressure structure 38.

The control circuit 56 further may be implemented to monitor sensor data which report one or more vital signs of the patient undergoing treatment with the device. For example, the inflatable structure 38 may include sensors for measuring skin temperature, pulse rate, respiration rate, or blood pressure. The control circuit 56 may monitor one or more of these vital signs of the patient to provide process control feedback, including safety alarms to prevent harm or excessive discomfort to the patient. For example, the control circuit 56 may instruct the system 10 to turn off or reduce the vacuum level of the negative pressure structure 38 should a vital sign measurement (e.g., the pulse rate or blood pressure) depart from a target level or range of values.

Referring to FIG. 5, the gas storage and delivery apparatus 14 may be contained in a housing 52, along with a power supply, control system and user interface 20. By contrast, the cuff 54 and negative pressure structure 38 may be attached to an exterior portion of the housing 52. The housing 52 may be separable from the cuff 54 and the negative pressure structure 38. Moreover, the cuff 54 and negative pressure structure 38 may be modular such that a used cuff and wound dressing assembly may be disconnected from the housing for disposal and then replaced with a new sterile cuff and wound dressing assembly. In this manner, the housing 52 may be reusable, but the cuff 54 and inflatable structure 38 may be disposable.

The size and configuration of the housing 52 may depend on the nature or location of the wound being treated. Accordingly, the size and configuration of the housing 52 may be determined, in part, by the size and configuration of the gas storage tank 22 and power supply 21. In the disclosed embodiment, the housing 52, cuff 54 and negative pressure structure 38 are shown in a mobile device, which may be similar to commercially available wrist-fitting blood pressure monitoring systems.

In use, the gas storage tank 22 may be filled from a high pressure supply of medical grade gas. A shut-off valve 24 on the gas storage tank 22 may be closed, and the regulator 26 of the gas delivery device may be disconnected from the shutoff valve 24. The shut-off valve 24 on the gas storage tank may then be connected to the source of medical grade gas 11. For example, the shut- off valve on the gas storage tank may be connected to a gas cylinder containing USP grade nitric oxide 1% in nitrogen with a supply pressure of approximately 100 psig. The shut-off valve 24 may then be opened to allow the gas storage tank 22 to fill with the therapeutic gas mixture. After the gas storage tank 22 is charged, the shut off valve 24 is closed, the source of medical gas 11 is disconnected from the shut-off valve, and the regulator 26 is reconnected to the shut-off valve. The regulator 26 then may be adjusted to deliver gas at a target delivery pressure. For example, the regulator 26 may be set to reduce the tank discharge pressure from approximately 100 psig to substantially equal to or greater than 5 psig. In this context, the term "approximately" means plus or minus 15% of the target level; whereas, the term "substantially equal to or greater than" means plus or minus 5% of the target level.

The wound area may be prepared by cleaning the wound area and securing a silicone gasket about the wound. The gasket 48 may include an adhesive material on the side facing the patient's skin in order to prevent fugitive emissions of therapy gas from escaping between the skin and the negative pressure structure 38. The negative pressure structure then may be placed over the wound and gasket 18. As shown in FIG. 19, the wound dressing 36 may include a window 51 to allow visual inspection and monitoring of the wound. Additional sealant may be placed between the silicone gasket 18 and the inflatable structure 38 to prevent fugitive emissions of therapy gas from breaking through the interface of the silicone gasket and the inflatable structure. The cuff (or other wrapping material) then may be placed around the inflatable structure and synched (or taped) to position or hold the wound dressing firmly against the patient.

The control circuit 56 may be powered on, and a microcontroller (or equivalent device(s)) may activate the vacuum pump 40 to evacuate gas and liquid from the interior space of the negative pressure structure 38 to create a negative pressure seal around the wound. The controller may verify establishment of the vacuum seal by monitoring the vacuum level and comparing the measured vacuum level to a preset level. Vacuum levels that are less than the preset level are indicative of an inadequate seal. Once the vacuum seal has been verified, the control system may open the shut-off valve 24 to release therapy gas to the dimple (or chamber) 44 in the negative pressure seal dressing 36. The therapy gas may fill the cavity formed by the dimple (or chamber) 44 in the negative pressure structure 38. Periodically, as active agent(s) in the therapy gas are consumed and exhausted, the atmosphere in the cavity may be purged to remove exudate or allow fresh therapy gas to recharge the chamber with active agent(s). This may be done manually by a user or automatically under the regulation of the control unit. Purging the cavity may include: closing the shut-off valve 24; opening the bleed valve (or purge valve) 30; allowing the pressure in the cavity to subside; closing the bleed valve 30; and then opening the shut-off valve 24.

Residual active agents in the purge gas (e.g., NO) may be removed by a suitable treatment process. After treatment has been completed, the system may be purged, the control circuit may be powered off, and the disposable components may be removed from the system 10 and discarded.

FIG. 6 presents a block diagram of another apparatus 10' for delivering therapeutic gas

(therapy gas) to a wound 12. The apparatus 10' includes a gas storage and delivery assembly 14' for supplying the pump and delivery assembly 19 with therapy gas for treating a wound, a negative pressure dressing delivery system 16 for delivering therapy gas to the wound 12, and a control system 18 which may include a user interface 20 and power supply 21 for regulating operation of the system 10'.

The gas storage assembly 14' may be configured and designed to store therapy gas at pressures lower than the delivery pressure of the therapy gas at the wound site. For example, the gas storage assembly 14' may be designed to store therapy gas at approximately 1.5 psig. The gas storage assembly 14' may be designed to supply the mechanical pump and delivery assembly 19 with therapy gas for a target time period. The target time period may correspond with a desired treatment cycle. For example, the therapy gas storage assembly 14' may be designed to supply the pump and delivery assembly 19 with therapy gas for approximately 7 days.

The pump and delivery assembly 19 may include a mechanical pump 40' which is fluidly connected to the therapy gas storage assembly 14". The mechanical pump 40' may pressurize the therapy gas from the storage assembly to provide a supply of therapy gas to the dressing 36 and wound headspace (at a constant or variable rate of flow) at a higher pressure than the pressure of the therapy gas in the storage assembly. For example, the mechanical pump and delivery system 19 may pressurize the therapy gas from the storage assembly 14' to supply therapy gas to the wound headspace within the dressing at approximately 5 psig.

Referring to FIG. 7, the therapy gas storage and delivery assembly 14' may include a gas storage tank 22', fittings (e.g., fill valve 24' and pressure regulator 26'), and flexible tubing 28 which supply the apparatus with medical grade therapy gas. The tank 22' may be designed to store and dispense a single charge of therapy gas. The tank 22" may be separable from the therapy gas storage assembly 14'. The gas storage tank 22' may be formed from a suitable thermoset material, thermoplastic material, a polymer composition, a fiberglass material or other material.

For example, the gas storage tank may be formed from a metal or a metal alloy (e.g., steel, aluminum, or stainless steel). The material further may include a glass fiber or synthetic fiber reinforcing material (e.g., nylon or Kevlar). Additionally, the gas storage tank may be constructed from a combination of materials. For example, the tank may be constructed with a metal liner with full composite overwrap (e.g., aluminum, with a carbon fiber composite). In another example, the tank may be constructed from a polymer (e.g., high-density polyethylene or HDPE) liner with carbon fiber or hybrid carbon/glass fiber composite materials.

The mechanical pump 40' may deliver therapy gas from the gas storage tank 22' to a pressure regulator 26'. The pressure regulator 26' may reduce and regulate the pressure of the therapy gas supplied by the mechanical pump 40' to deliver and maintain a steady output pressure within the dressing 36 at the wound. For example, the mechanical pump may deliver therapy gas at a substantially constant rate of flow (e.g., 3.3 mL/hr) and at a pressure in excess of 6 psig, and the regulator may reduce or regulate the pressure of the therapy gas supplied by the mechanical pump to maintain a steady output pressure of approximately 5 psig. In this context, the term "approximately" means plus or minus 15% of the target level; whereas, the term "substantially constant" means plus or minus 1% of the target level.

As shown in FIG. 8, a mechanical pump 40' may supply therapy gas to the wound headspace within the dressing without a pressure regulator. In this embodiment, the control circuit 56 may regulate operation of the mechanical pump 40' to achieve the desired pressure within the dressing 36 at the wound headspace. In this configuration, the pressure profile of the therapy gas may range from 0 psig to a set point for the maximum desired pressure within the dressing at the wound headspace.

Referring to FIG. 7 and FIG. 8, the negative pressure dressing delivery system 16, vacuum pump 40, gas capture device 74, control and monitoring system 18', user interface 20' may generally operate as described in connection to the embodiment shown in FIG. 2, along with any additional processes (e.g., power supply) being regulated and process parameters being monitored (e.g., gas pump condition) to effectuate efficient operation of the apparatus.

As shown in FIG. 11, another embodiment of the wound dressing 36 may include a negative pressure structure 38 which may be shaped as a tubular member that is configured and dimensioned to surround a limb, torso, or extremity 70. The tubular member may be used to create and secure a sealed cavity about a wound site. The wound dressing may include the discharge end of the flexible tubing 28 from the regulator 26 and therapy gas storage tank assembly 14. The flexible tubing 28 may pass through the negative pressure structure 38 to deliver the therapy gas to the wound. Penetrations 42 in the negative pressure structure 38 may be sealed. The flexible tubing 28 may be positioned directly near the wound or connected to a pocket (or dimple) 44 in the negative pressure structure 38, which may include one or more openings (or apertures) 42 for delivering therapy gas to the wound. The tubular member may be formed from a soft, flexible, and gas tight material. For example, the tubular member may be formed from an elastomeric material. Suitable materials for the tubular member may include, without limitation, silicone, polyurethane, and PVC.

The dimple (or chamber) 44 may be located on a skin contact surface 41 which may be a generally flat and smooth portion of an interior surface 53 of the negative pressure structure 38. The skin contact surface 41 may be a flexible wall of the negative pressure structure 38. The negative pressure structure 38 further may include multiple ports 43 in the skin contact surface 41, as well as the broader interior surface 53. Each port 43 may extend through the skin contact surface 41 or interior surface 53 of the flexible wall to fluidly connect these areas with an interior space 45 (not shown) located within the negative pressure structure 38. For example, the interior space 45 may be bounded by the flexible wall, as well as by other walls or features of the negative pressure structure 38. The flexible wall may be formed from medical grade silicone rubber or another flexible material that is suitable for skin contact. The interior space within the negative pressure structure 38 may be fluidly connected to a mechanical pump 40 via a conduit 50. The negative pressure structure 38 further may include quick disconnect connections (not shown) for attaching the flexible tubing 28 and the conduit 50 to the aperture 44 and interior space 45 (not shown), respectively. The conduit may be formed from flexible tubing 28 provided the pathway for conveying gas and liquid mixtures generally does not collapse or otherwise occlude gas and liquid transport when subject to negative pressure supplied by the pump 40. A capture device 74 (not shown) may be fluidly connected to conduit 50 and the mechanical pump 40 as described above with respect to FIG. 7 and FIG. 8.

The wound dressing 36' further may include a gasket 48 and sealing materials which may be placed in direct contact with skin adjacent to the wound to create a sealed chamber about the wound. For example, a gasket material 48 formed from silicone may be cut by a caregiver to fit the wound site. The silicone material may include a metal foil coating. Additionally, the gasket material may include an adhesive surface to seal the gasket to the patient's skin in an effort to prevent leaks from developing between the wound dressing and the patient's skin. Additional adhesives or sealants may be used to isolate the chamber. Preferably, the negative pressure structure 38 and any gasket materials 48 and sealants used to create the sealed cavity about the wound may be compatible with skin contact. The sealed cavity may then be filled with therapy gas to topically treat the wound.

The negative pressure structure 38 may be shaped for a particular anatomy to help secure the dimple about the wound. In one embodiment, the negative pressure structure 38 may be generally tubular in shape, and the therapy gas discharge site 44 may be located in the middle of the negative pressure structure. The negative pressure structure may be draped over the wound and deflated to create a sealed chamber. Using a negative pressure structure 38 to create a sealed cavity about the wound reduces compressive forces otherwise needed to confine the pressurized therapy gas to the wound area. This may reduce restriction of blood flow relative to a compressive dressing. The negative pressure structure 38 may be configured and dimensioned to surround a particular anatomy (e.g., a toe, a foot, an arm, a leg, a torso, and such.) The inflatable structure may be adapted for use in treating dogs, horses or other animals.

FIG. 12 shows another embodiment of a mobile dressing 36 for therapeutically delivering pressurized gas to a wound. The mobile dressing 36 may include a negative pressure structure 38 with one or more openings (or apertures) 46 for supplying therapy gas to a wound, a lumen 28 fluidly connected to the one or more openings 46 in the inflatable structure (or bladder) 38, and another lumen 50 for supplying a vacuum to evacuate gas and liquids from the negative pressure structure 38. The mobile dressing may include a fabric wrap 54 with Velcro fastener strips which may be used to assist in securely positioning the bladder at the treatment site. The pressure dressing 36 is substantially the same as the mobile dressing presented in FIG. 4, except that a low pressure storage tank 22' and a mechanical pump 40' may be used to deliver therapy gas to the lumen 28 which is fluidly connected to the one or more openings 42 in the inflatable structure 38. For instance, the therapy gas may be stored at approximately 1.5 psig and delivered to the one or more openings at approximately 5 psig. Moreover, the vacuum supply conduit 50 may include a purge valve 30 and a capture device 74. The purge valve 30 may be normally closed during wound care. The purge valve, however, may be opened to purge the headspace of the wound. Purged gases may be captured in the capture device 74. The capture device 74 may include a catalyst that renders the purged gases harmless, as well as a trap for collecting and storing exudate. The trap may include absorbent material for immobilizing the exudate. The absorbent material may include, without limitation, polyurethane foam, hydro-colloids, hydrogels, or other absorbent materials. The capture device may include an adsorbent or molecular sieve that safely stores the purged gases. The catalyst, adsorbent, or molecular sieve may be adapted for a particular therapy or carrier gas. For example, a platinum-based catalyst may be used to oxidize or reduce gaseous compounds to less objectionable compounds so that they can be released to the atmosphere.

FIG. 13 shows another embodiment of a mobile system 10"' for delivering pressurized gas to a wound. In this embodiment, a third lumen 76 is fluidly connected to the one or more openings 42 in the negative pressure structure 38. The third lumen 76 may be fluidly connected to the purge valve 30 and the capture device 74. In this configuration, the purge valve 30 may be opened and therapy gas may be used to flush the first lumen 28, the dimple 44 cavity, and the third lumen 76 with therapy gas. Additionally, the intake of the mechanical pump 40' which delivers the therapy gas to the first lumen 28 may be selectively connected to a vent (not shown) to provide a supply of ambient air for purging gases from the wound headspace.

FIG. 14 shows yet another embodiment of system for therapeutically delivering pressurized gas to a wound. In this embodiment, the first lumen 28 and the third lumen 76 of FIG. 13 may be replaced by a multiple-lumen tubing. For example, the inner lumen 28' may functionally correspond to the first lumen 28 (FIG. 13) and may deliver pressurized therapy gas to the one or more openings 46 in the inflatable structure 38. The outer lumen 76' may functionally correspond to the third lumen 76 (FIG. 13) and may transport gases from the one or more openings 46 to the purge valve 30 and capture device 74.

FIG. 15 depicts the negative pressure dressing 36' of FIG. 11 secured to a limb 70 of a patient. The negative pressure dressing 36' includes a negative pressure structure 38, a dimple 46, a gasket 48, as well as a pressurized therapy gas supply tubing 28 and a vacuum source conduit 30. As shown in FIG. 17, the negative pressure dressing 38 may circumscribe a limb 70 of the patient to present a tubular dressing configuration. The dimple 44 may be disposed over the wound 12 and a gasket 48 is placed between the wound site and negative pressure dressing to facilitate a gas-tight seal between the wound 12 and the dimple 44 enclosed cavity, as well as the interior space 45 of the negative pressure structure 38. The negative pressure dressing 38 further includes a window 51 in the dimple over the enclosed cavity for visually monitoring the wound site. Pressurized therapy gas is delivered to the enclosed cavity and wound site through the aperture 46 in the dimple 44. Ports 43 in the generally flat and smooth surface 53 apply negative pressure to the limb 70 to secure the position of the dressing 36' and seal the dimple 44 enclosed cavity to prevent fugitive emissions of pressurized therapy gas.

FIG. 16 depicts the negative pressure dressing 36 of FIG. 4 secured to a limb 70 of a patient. The negative pressure dressing 36 includes a negative pressure structure 38, a dimple 46, a gasket 48, as well as a pressurized therapy gas supply tubing 28 and a vacuum source conduit 30. As shown in FIG. 18, the negative pressure dressing 38 is pressed against the limb 70 of the patient to present a spot dressing configuration. The dimple 44 may be disposed over the wound and a gasket 48 may be placed between the wound site and negative pressure dressing 36 to facilitate a gas-tight seal between the wound 12 and the dimple 44 enclosed cavity, as well as the interior space 45 of the negative pressure structure 38. The negative pressure dressing 38 further may include a window 51 in the dimple 44 over the enclosed cavity for visually monitoring the wound site. Pressurized therapy gas is delivered to the enclosed cavity and wound site through the aperture 46 in the dimple 44. Ports 43 in the generally flat and smooth surface 53 may apply negative pressure to the limb 70 to secure the position of the dressing 36 or seal the dimple 44 enclosed cavity to prevent fugitive emissions of pressurized therapy gas.

Referring to FIG. 19 and FIG. 20, the negative pressure seal dressing may be formed from an upper portion 59 that includes a window 51 and quick disconnect structures 47, 49, as well as a lower portion that includes the skin contact surface 41 and vacuum ports 43. The upper portion may be formed from a more rigid material, and the lower portion may be formed from a more flexible material. The ports 43 may be arranged on the contact surface to facilitate sealing of the dimple enclosed cavity to prevent fugitive emissions of pressurized therapy gas. The upper portion and lower portion may be molded as separate parts and fitted and sealed together. Additionally, the negative pressure seal dressing may be fabricated by additive manufacturing.

FIG. 21 shows an exploded view of negative pressure dressing 36 of FIG. 19. In this embodiment, the dimple 44 is formed by an interior wall 80in the upper portion 57 and a guide wall 82 that slidably receives the interior wall 80 to create a passage 84 and chamber (or dimple)

44 for delivering pressurized therapy gas to a wound site through an opening 86 at the bottom of the chamber (or dimple) 44. The opening 86 may extend through the lower portion 59 of negative pressure structure 38 to the skin contact surface 41.

FIG. 22 shows the interior wall 80 received within the guide wall 82 to create the passage 84 and chamber (or dimple) 44. Indeed, FIG. 23 shows the passage 84 and chamber (or dimple) 44 for delivering pressurized therapy gas through the opening 86 at the bottom of the chamber, as well as the separate interior space 45 of the negative pressure structure. By contrast, FIG. 24 shows the interior space 45 fluidly connecting the vacuum supply port 49 to the ports 43 on the skin contact surface 41.

FIG. 25 shows another embodiment of a negative pressure dressing 36 which includes curved spacers or baffles 88 in the upper portion 57 that may facilitate application of enhanced levels of negative pressure to the vacuum application ports 43 nearest the opening 86 at the bottom of the chamber. As shown in FIG. 26, the baffles 88 and vacuum ports 43 may be arranged in a generally concentric circular configuration. FIG. 27 shows the passage 84 and chamber (or dimple) 44 for delivering pressurized therapy gas through the opening 86 at the bottom of the chamber (or dimple) 44, as well as three separate fluidly connected segments 90, 92, 94 within the interior space 45 of the negative pressure structure 38. Baffles or spacers 88 in the negative pressure structure 38 may prevent the interior space 45 from collapsing and occluding the vacuum supply to the ports 43, and thus may facilitate the application of a vacuum at the ports 43 in the skin contact surface 41.

FIG. 28 shows yet another embodiment of a negative pressure dressing 36 having curved segments 88 as spacers or baffles in the upper portion 57 to distribute gas flow within the interior space 45, and thus potentially facilitate greater uniformity in the application of negative pressure to ports 43in the skin contact surface 41. As shown in FIG. 29, the curved segments 88 and vacuum ports 43 may be arranged in a generally concentric circular configuration.

FIG. 30 shows yet another embodiment of a negative pressure dressing 36 having linear segments 96 as spacers or baffles in the upper portion 57 to affect the application of negative pressure to the vacuum application ports in the skin contact surface. As shown in FIG. 31, the linear segments 96 and vacuum ports 43 may be arranged in a segmented linear array configuration.

FIG. 32 shows yet another embodiment of a negative pressure dressing 36 having linear segments 96 as spacers or baffles in the upper portion 59 connected to a side capillary 98 vacuum supply to affect the application of negative pressure to the ports 43 in the skin contact surface 41. As shown in FIG. 33, the segmented baffles 96 and vacuum ports 43 may be arranged in a capillary configuration. FIG. 34 and FIG. 35 show yet another embodiment of a negative pressure dressing 36 having a solid porous structure (e.g. foam) 100 in the interior space 45 to distribute air flow and prevent the interior space 45 from collapsing and occluding the vacuum supply 49 to the ports 43 in the skin contact surface 41.

FIG. 40 and FIG. 41 show another exemplary embodiment of a negative pressure seal dressing 36. The negative pressure seal dressing 38 may include a negative pressure structure 38. The negative pressure structure may be formed from a hollow annular member. The inner surfaces of hollow annular member may define an interior space of the negative pressure structure

38. The negative pressure structure may include a quick disconnect structure 49 that is in fluid communication with the interior space. This quick disconnect structure 49 may be used to connect the interior space to a vacuum supply. The hollow annular member further may include multiple ports 43 on the bottom of the negative pressure structure 38, which extend from a skin contact surface 41 to the interior space 45. The hole defined by the hollow annular member may be open on the bottom (i.e., the side of the skin contact surface) of negative pressure structure 38. The opposite end of the hole defined by the annular member may be sealed by a cover 55 to form a gas-tight pocket (or chamber) 44. The cover 55 may be a separate layer of material that is bonded or fixed to adjacent portions of the hollow annular member. The cover and adjacent portions of the hollow annular member may form a gas-tight connection. The cover may be formed from a clear material or may include a window 51 above the hole that is defined by the hollow annular member. The cover may be formed from a material which is relatively more rigid that the hollow annular member. The cover may include an opening for a fitting. The fitting may include a tubular member that includes a quick disconnect structure 47 on the other end of the tubular member. The fitting may be inserted into the opening to provide a sealed passage for transporting pressurized therapy gas from the quick disconnect structure 59 to the pocket 44. Referring to FIG. 41, the negative pressure structure 38 may be positioned above a wound site such that the pocket 44 is disposed over the wound 12. A gasket 48 may be placed between the negative pressure structure 38 and the wound 12. A vacuum source (e.g. 80-120 mmHg) may be connected to the quick disconnect structure 49 that is in fluid communication with the interior space 45 to evacuate gas and liquid from the interior space 45, maintain negative pressure within the interior space, and seal the pocket about the wound. Pressurized therapy gas may then be delivered to the wound via the pocket 44 and the associated fitting and quick disconnect structure 47.

FIG. 36 shows a perspective view of exemplary packaging 102 for a kit 104 containing an apparatus for therapeutically applying gas to a wound. For example, the packaging 102 may include a thermoformed tray 106 and a custom-matched die cut lid 108. As shown in FIG. 37 and FIG. 38, the kit 102 may include a negative pressure dressing 36, a device 110 for supplying pressurized therapy gas and a vacuum to the dressing, as well as instructions 112 and other consumables (e.g., batteries, therapy gas canister, sterile gaskets and flexible tubing) for treating a wound with pressurized therapy gas. In FIG. 38 the negative pressure dressing 36 is a tubular dressing configuration; whereas, in FIG. 37 the negative pressure dressing 36 is a spot dressing configuration. Other shapes and configurations may be developed for particular clinical applications or needs including nesting shapes which may be used together for delivering therapy gas to larger or highly irregular wounds.

FIG. 39 shows the contents of the exemplary kit 104 of FIG. 38, which may include a negative pressure dressing 36 for delivering pressurized therapy gas to a wound, a portable device llOfor supplying a pressurized therapy gas and a vacuum source to the dressing, a pair of rechargeable (or single use) batteries 114 for powering the device, a supply of therapy gas 116, two flexible tubing segments 117 for connecting the device to the dressing, several, individually packaged and sterile gaskets 119, and an instruction manual 112 for assembling and operating the apparatus for treating wounds with pressurized therapy gas. The contents of the exemplary kit of FIG. 37 may include the same items as the exemplary kit of FIG. 39, except that the negative pressure dressing 6 is a spot dressing configuration.

In use, a negative pressure seal dressing may be used to administer pressurized therapy gas treatment to a wound. The wound may be cleansed and debrided. A negative pressure seal dressing may be selected for treating the wound based on clinical factors such as the location of the wound (e.g., foot, leg, or coccyx). A sterile gasket may be placed around the wound, and the selected negative pressure seal dressing may be applied to the wound location. Negative pressure may be applied to the negative pressure seal dressing to secure a seal around the wound area. Once a desired negative pressure level is reached in the negative pressure structure, the infection treating gas - e.g., NO - may be administered to the pocket (or chamber) of the negative pressure seal dressing. The pressurized therapy gas in the pocket (or chamber) may be maintained at the desired pressure level above the wound. After the desired time of treatment has lapsed (e.g., 30 minutes for NO), the therapy gas may be stopped and a purge cycle may be initiated to remove any residual therapy gas. If wound healing treatment with oxygen has been ordered then oxygen at 5-15 psig may be administered to the pocket (or chamber) over the wound. Topical oxygen therapy may be maintained at that level until the next infection treatment cycle. For example, the frequency of wound healing treatment with NO oxygen may range from one cycle per hour to once cycle per 8 hours. The prescribed therapy cycle may be repeat until it has been determined that the infection in the wound has abated. Thus, the negative pressure seal dressing may be used to administer infection-fighting gas treatment, continuous oxygen therapy, alone or in combination.

Various gases may be administered to a wound in an intermittent, sequential, or combined configuration to address a particular therapeutic goal. For example, nitric oxide may be applied to kill bacteria; and then oxygen may be applied to enhance growth factors and granulation. In another example, ozone may be applied to kill bacteria, followed by the application of oxygen to enhance growth factors and granulation. In yet another example, nitric oxide may be applied to kill bacteria and then nitrogen or carbon dioxide may be administered to enhance angiogenesis.] While it has been illustrated and described what at present are considered to be embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the invention. For example, a different pump may be used to evacuate the negative pressure structure or to pressurize a low-pressure supply of therapy gas. In another example, the fabric cover may be disposable and thus the cuff may be reusable with one or more replacement fabric covers. Additionally, features and/or elements from any embodiment may be used singly or in combination with other embodiments. Therefore, it is intended that this invention not be limited to the particular embodiments disclosed herein, but that it have the full scope defined by the language of the following claims, and equivalents thereof.

Claims

CLAIMS What is claimed is:

1. A dressing for therapeutically delivering pressurized therapy gas to a wound comprising:

a negative pressure structure which comprises

a hollow annular member comprising

an inner surface on one side of the hollow annular member,

an exterior surface on the other side of the hollow annular member, an interior space bounded by the inner surface,

a skin contact surface on the exterior surface, the skin contact surface comprising a plurality of ports each of which extend from the skin contact surface to the interior space, and

a central bore defined by the exterior surface; and

a cover disposed over the central bore to form a sealed pocket, the cover comprising

a first opening extending through the cover;

a fitting disposed in the first opening which comprises

a tubular member comprising a first end and a second end, the first end being in fluid communication with the pocket, and

a second opening on the second end of the fitting, the second opening being in fluid communication with the first opening.

2. The dressing of claim 1 further comprising:

a first lumen fluidly connected to the second opening for delivering pressurized therapy gas to the pocket.

3. The dressing of claim 2 further comprising:

a second lumen connected to the hollow annular member, the second lumen being fluidly connected to the interior space for evacuating gas and liquid from the interior space.

4. The dressing of claim 3, wherein the interior space is subject to a vacuum and the pocket is subject to a pressurized gas.

5. The dressing of claim 4, wherein the vacuum level in the interior space ranges from 2 mmHg to 250 mmHg.

6. The dressing of claim 4, wherein the pressurized gas in the pocket ranges from 5-15 psig.

7. The dressing of claim 6, wherein the pressurized gas is oxygen.

8. The dressing of claim 6, wherein the pressurized gas is a mixture of 1% nitric oxide and 99% nitrogen.

9. The dressing of claim 1, further comprising a tank of therapy gas fluidly connected to the second opening.

10. The dressing of claim 4, wherein the tank is designed to store therapy gas at a pressure substantially equal to or less than 5 psig.

11. The dressing of claim 10, wherein the tank is a refillable gas storage device.

12. The dressing of claim 11, wherein the tank is configured to store and dispense a single charge of therapy gas.

13. The dressing of claim 2, further comprising a purge valve fluidly connected to the first lumen.

14. The dressing of claim 3, further comprising a capture device fluidly connected to the second lumen.

15. The dressing of claim 14, wherein the capture device comprises a catalyst that interacts with purged therapy gas to render purged therapy gas harmless.

16. The dressing of claim 15, wherein the catalyst is a platinum-based catalyst.

17. The dressing of claim 14, wherein the capture device comprises a molecular sieve that safely stores purged therapy gas.

18. The dressing of claim 14, wherein the capture device comprises an adsorbent that safely collects and stores purged exudate.

19. The dressing of claim 2, further comprising a pressure regulator, the pressure regulator being fluidly connected to the first lumen such that the pressure regulator is configured to deliver pressurized therapy gas at a pressure substantially equal to 5 psig to the first lumen.

20. The dressing of claim 19, further comprising a pressure cylinder capable of supplying therapy gas continuously for 10 days at a discharge pressure ranging from approximately 1.1 psig to approximately 1.5 psig.