Patent Description:
Wound care is desirable in order to improve health, enhance healing, and to reduce potential for infections of the outer epidermis, as well as underlying dermal and other tissues/organs. Wounds, either injury induced, or surgically induced, such as saphenous vein harvesting, require localized treatment to remedy the affected area and prevent further damage. If wounds are not properly treated, further complications can result, including wound irritation, secondary infections and further discomfort to the subject.

Improper wound care and/or wound healing result in greater costs and expenses, and may require antibiotic use, hospitalizations, and great pain or discomfort to the subject. Present methods of therapeutic wound care may still lead to higher than necessary infection rates and/or longer wound repair/recovery time. Thus, novel therapeutic methods and devices for wound care and wound healing are needed.

Therapeutic gases may be applied to the body for treatment of a variety of medical conditions. Carbon dioxide is a desirable therapeutic gas that has a bacteriostatic function, reducing the growth of bacteria and/or other microorganisms, which possibly may be present on or around medical treatment instruments, and at or around the wound or surgical site. Another desirable therapeutic effect of carbon dioxide gas is its high solubility rate in the tissues of the body relative to oxygen and nitrogen.

During operations which are performed in an open manner, i.e. when an inner portion of the body is uncovered for the performance of the surgical operation, it may be important to prevent air from the environment from reaching the open portion of the body. A gas diffuser (or gas insufflator) can be used to modify the local atmosphere around the operation by delivering the desired gas to the surgical site. Carbon dioxide is heavier than air so that a protective gas atmosphere in a volume adjoining an outwardly open, inner portion of a human being may be created in an easy manner. It is to be noted that the gas may be supplied to the volume in a continuous flow, wherein it is possible to ensure that the surrounding air is prevented from reaching the volume even if a part of the supplied gas leaves the area. During some surgical procedures, gas diffusers/insufflators deliver carbon dioxide gas into the open cavity of the surgical site to modify the local atmosphere in the open cavity so that it is as near to <NUM> percent CO<NUM> as possible. This modification of the local atmosphere has been shown to not only reduce the number of air emboli and therefore reduce the potential for a patient to suffer a stroke or organ damage from emboli, but to also have the potential to reduce infections.

Gas diffuser/insufflators are known, but improved gas diffusers that provide a more convenient, inexpensive and accurate delivery of a therapeutic gas to the wound or surgical site while having the ability to maintain a stable local atmosphere of the therapeutic gas are needed. Further needed are gas diffuser/insufflators with improved ability to filter and deliver the therapeutic gas to the treatment site in order to enhance healing, reduce potential for bacterial infection and lessen the need for antibiotics.

A gas diffuser device arranged to deliver a gas to a treatment site, the device being connectable to a gas source, the device including a gas inlet connectable to the gas source, (i) a first membrane comprising a flexible, hydrophobic, microporous polymer body having a pore size of <NUM> or less and (ii) a second membrane comprising a flexible nonporous or substantially nonporous polymer body. When the flexible, hydrophobic, microporous polymer body of the first membrane has a pore size of <NUM> or greater, the gas inlet has a bacterial filter.

Optionally, the second membrane may comprise a polymer having a pore size smaller than the pore size of the first membrane and/or a bacterial efficiency that is greater than the bacterial efficiency of the first membrane. The first and second membranes of the device each have outer edge portions and the outer edge portions of the second membrane are bonded to the outer edge portions of the first membrane to form an interior chamber of the device, the interior chamber of the device confining introduced gas to the interior chamber such that the introduced gas flows out through the pores of the first membrane. The gas is introduced into the interior chamber through a gas inlet of the device and the gas inlet is connectable to the gas source. The flexible, hydrophobic, microporous polymer body of the first membrane of the device is arranged to diffuse the introduced gas into the treatment site and the device is arranged such that the introduced gas maintains a gas atmosphere along the treatment site. The invention also provides a system including a gas source and such a device.

The invention also provides a gas diffuser device that includes a flexible, microporous polymer body having a pore size <NUM> or greater. Further, the pore size of the microporous polymer body could be in a range of <NUM> to <NUM>. Where the microporous polymer body of the first membrane has a pore size of <NUM> or greater, a bacterial filter is provided in the gas supply line or the gas inlet of the device to filter the gas supply. The invention also provides a system including a gas source and such a device.

Preferred forms of the present invention will now be described by way of examples with reference to the accompanying drawings.

In one embodiment the invention is a device arranged to deliver a gas to a treatment site, the device being connectable to a gas source, the device including (i) a first membrane comprising a flexible, hydrophobic, microporous polymer body (ii) a second membrane comprising a flexible nonporous or substantially nonporous polymer body. Optionally, the second membrane may comprise a polymer having a pore size smaller than the pore size of the first membrane. The first and second membranes of the device each have outer edge portions and the outer edge portions of the second membrane are bonded to the outer edge portions of the first membrane to form an interior chamber of the device, the interior chamber of the device confining introduced gas to the interior chamber such that the introduced gas flows out through the pores of the first membrane. The gas is introduced into the interior chamber through a gas inlet of the device and the gas inlet is connectable to the gas source. The flexible, hydrophobic, microporous polymer body of the first membrane of the device is arranged to diffuse the introduced gas into the treatment site and the device is arranged such that the introduced gas maintains a gas atmosphere along the treatment site.

In another embodiment the invention is a device arranged to deliver a gas to a treatment site, the device being connectable to a gas source, the device including (i) a first membrane comprising a flexible, hydrophobic, microporous polymer body having a pore size of <NUM> or less and (ii) a second membrane comprising a flexible nonporous or substantially nonporous polymer body. Optionally, the second membrane may comprise a polymer having a pore size smaller than the pore size of the first membrane. The first and second membranes of the device each have outer edge portions and the outer edge portions of the second membrane are bonded to the outer edge portions of the first membrane to form an interior chamber of the device, the interior chamber of the device confining introduced gas to the interior chamber such that the introduced gas flows out through the pores of the first membrane. The composition of the material of the second membrane prevents or inhibits the gas from escaping through the second membrane and directs or forces the gas through the pores of the first membrane. The gas is introduced into the interior chamber through a gas inlet of the device and the gas inlet is connectable to the gas source. The flexible, hydrophobic, microporous polymer body of the first membrane of the device is arranged to diffuse the introduced gas into the treatment site and the device is arranged such that the introduced gas maintains a gas atmosphere along the treatment site.

The advantage of letting the gas pass through the microporous polymer body of the first membrane having a pore size of <NUM> or less is that the pores of the microporous polymer body, which are great in number and positioned very closely to each other, filter bacteria that may present. The average diameter of spherical bacteria is <NUM>-<NUM>. For rod-shaped or filamentous bacteria, the average length is <NUM>-<NUM> and the average diameter is <NUM>-<NUM>. Specific examples of bacteria include: E. coli having an average size of about <NUM> to <NUM> wide by <NUM> to <NUM> long; Spirochetes ranging from <NUM> to <NUM> in length; the cyanobacterium Oscillatoria being about <NUM> in diameter. Additionally, one group of bacteria called the mycoplasmas, have individuals with size much smaller than these dimensions. They can measure about <NUM> and are the smallest cells known so far. They were formerly known as pleuropneumonia-like organisms (PPLO). Mycoplasma gallicepticum, with a size of approximately <NUM> to <NUM> are thought to be the world smallest bacteria. Therefore a microporous polymer body that has a microporous polymer body having pore sizes of <NUM> or less will thus filter and remove most/almost all bacteria from the gas supply. The microporous polymer body of the first membrane a pore size of <NUM> or less can also filter other microorganisms, impurities, or other foreign substances that also may be present.

Another advantage of letting the gas passing through the microporous polymer body of the first membrane is that the pores can function as a multiplicity of supply nozzles, and may distribute the gas in thin layers lying close to each other and forming, when the gas leaves the microporous polymer body, a substantially laminar continuous gas flow. The flexible, hydrophobic, microporous polymer body of the first membrane also causes the gas to exit through pores over the majority of the body thereby preventing a singular jetting action.

Diffusion of the gas, preferably carbon dioxide, through the microporous first membrane into the treatment site is advantageous because carbon dioxide has a high solubility in the tissue of the body relative to oxygen and nitrogen, has a bacteriostatic function, which reduces the growth of bacteria and/or other microorganisms and is heavier than air. These features of carbon dioxide aid in the enhancement of healing at the treatment site; aid in the reduction of the potential for bacterial infections at the treatment site; lessen the need for antibiotics at the treatment site; and aids in the creation of a therapeutic and protective gas atmosphere at the treatment site.

In another embodiment the first membrane of the device may include a flexible, microporous polymer body having a pore size of <NUM> or greater, and that could be in a range of <NUM> to <NUM>. In applications where the microporous polymer body of the first membrane has a pore size larger than <NUM>, a bacterial filter is provided in the gas supply line or the gas inlet of the device to filter the gas supply.

In an embodiment the introduced gas is CO<NUM>. In another embodiment the device is arranged to attach to the treatment site by an adhesive positioned on the first membrane, by an adhesive positioned on the second membrane, or both. In an embodiment the device has edges and the device has a shape formed from the edges of the device, the shape being rectangular, square, triangular, oval, trapezoidal or circular The flexible, microporous polymer body of the first membrane is hydrophobic. In an embodiment the flexible, microporous polymer body of the first membrane is made of polytetrafluoroethylene and the flexible, nonporous or substantially nonporous polymer body of the second membrane is also made of a polytetrafluoroethylene. In another embodiment the flexible, microporous polymer body of the first membrane is coated with an antibacterial substance and a medicated substance.

In another embodiment the device includes a pressure relief valve whereby introduced gas in the interior chamber of the device can be diverted from the interior chamber and through the pressure relief valve to maintain a desired gas pressure along the treatment site. In an embodiment the device includes a flush line port whereby introduced gas in the interior chamber of the device can be diverted from the interior chamber and through the flush line port to flush the introduced gas through the device. In another embodiment the device includes an open cell sponge support material, the open cell sponge support material being positioned in the interior chamber in direct contact with the flexible, microporous polymer body of the first membrane. In another embodiment the device includes shapeable structures positioned throughout the device and arranged to conform and shape the device around the treatment site.

The invention also provides a system comprising a gas source and such a device having a first membrane with a microporous polymer body having a pore size of <NUM> or less. The gas insert of the device can be connected directly to the gas source or can be connected to a flexible hose portion (or other gas delivery means) that is then connected to the gas supply. In some embodiments of the system, the microporous polymer body of the first membrane of the device may have a a pore size larger than <NUM>. In such embodiments of the system, a filter is provided in the flexible hose portion (or other gas delivery means) or the gas inlet of the device to filter the gas supply. The filter positioned in the gas inlet or the flexible hose portion may have a housing made of polypropylene and may have glass fibers as a filter material. The filter may have a pore size between <NUM> to <NUM>. It is to be understood that the filter could be made of any desired material and could have any desired pore size as needed to properly and adequately filter the gas supply. In an embodiment, the gas comprises a majority of carbon dioxide.

Also disclosed but not part of the invention is a method for delivering a gas to a treatment site including providing a device arranged to deliver gas to a treatment site, the device being connectable to a gas source, the device having (i) a first membrane comprising a flexible, microporous polymer body having a bacterial filtration efficiency of <NUM>% or greater and/or a pore size of <NUM> or less and (ii) a second membrane comprising a flexible nonporous or substantially nonporous polymer body. Optionally, the second membrane may comprise a polymer having a pore size smaller than the pore size of the first membrane and/or a bacterial efficiency that is greater than the bacterial efficiency of the first membrane. The first and second membranes of the device each have outer edge portions and the outer edge portions of the second membrane are bonded to the outer edge portions of the first membrane to form an interior chamber of the device. The composition of the material of the second membrane prevents or inhibits the gas from escaping through the second membrane and directs or forces the gas through the pores of the first membrane. The method not according to the invention including positioning and attaching the device to the treatment site; connecting the gas inlet of the device to the gas source; and supplying the gas to the interior chamber of the device through the gas inlet, the interior chamber of the device confining the supplied gas such that the supplied gas flows out through the pores of the first membrane of the device and diffuses the supplied gas into the treatment site. The method not according to the invention includes that the supplied gas maintains a gas atmosphere along the treatment site.

In some embodiments not according to the invention of the method, the microporous polymer body of the first membrane of the device may have a bacterial filtration efficiency of less than <NUM>% and/or a pore size larger than <NUM>. In such embodiments, not according to the invention the first membrane could have a bacterial filtration efficiency of <NUM>% or greater, <NUM>% or greater or could be in a range of <NUM>% to <NUM>%. Additionally/alternatively the first membrane could have a pore size in a range of <NUM> to <NUM>. In such embodiments of the method, not according to the invention a bacterial filter may be provided in the flexible hose portion of the gas source or the gas inlet of the device to filter the gas supply. In an embodiment, the gas comprises a majority of carbon dioxide.

<FIG> shows a gas diffuser or insufflator device <NUM> of the invention (in cross-section connected to a gas source <NUM>. The gas diffuser device <NUM> has gas inlet <NUM>, first membrane <NUM>, interior chamber <NUM>, second membrane <NUM> and flush line outlet or port <NUM> (optional). Gas diffuser device <NUM> may also have an overpressure relief valve <NUM>. Gas may be supplied from the gas source to the device by flexible gas hose <NUM> that has intake end <NUM> connected to gas source <NUM> and discharge end <NUM> connected to the gas inlet <NUM> of the gas diffuser device <NUM>. It should be understood that any desired gas delivery structure or means can be used to supply gas to the device.

<FIG> shows a view of the wound covering surface of gas diffuser <NUM>. First membrane <NUM> is a microporous membrane through which a supplied gas is filtered and diffused to a treatment site. The treatment site may be a wound or surgical site depending upon the application. First membrane <NUM> may be made of a flexible microporous polymer such as polytetrafluoroethylene and, more specifically, could be made of POREX® Virtek™ PTFE MD10. It is to be understood that the material composition of first membrane <NUM> is non-limiting and could be any microporous polymer that filters bacteria and other impurities as discussed further below. First membrane <NUM> may have a thickness as desired and could be <NUM>. First membrane <NUM> is hydrophobic and non-wetting. First membrane <NUM> has pores <NUM> positioned close together across the first membrane <NUM> and are distributed across the first membrane in great number and high concentration. Pores <NUM> prevent the passage of bacteria and other microbes in addition to other impurities larger than the size of the pore from diffusing through first membrane <NUM> to the treatment site, thereby filtering the gas supplied or introduced to the device. Thus, first membrane <NUM> can function as a bacterial filter allowing the desired gas to pass through pores <NUM> while preventing bacteria from passing through pores <NUM>. The bacterial filtration property of first membrane <NUM> can have a desired efficiency of bacterial filtration. The bacterial filtration efficiency of the flexible, microporous polymer body of the first membrane <NUM> can be determined/measured in accordance with ASTM F2101-<NUM>. The desired bacterial efficiency of first membrane <NUM> as determined by ASTM F2102-<NUM> could be <NUM>% or greater, <NUM>% or greater, <NUM>% or greater or could be in a range of <NUM>% to <NUM>% as desired. (It should be understood that the bacterial filtration efficiency could also be less than <NUM>% depending upon the application). In some applications where the bacterial filtration efficiency of first membrane <NUM> is less than <NUM>%, a separate filter (F shown with optional locations in <FIG>) is provided to the gas source, gas supply line or the gas inlet of the gas diffuser device to filter out bacteria and other impurities.

Optionally, pores <NUM> of first membrane <NUM> may have a specific desired size. The desired size could be <NUM> microns or less, the desired pore size could be <NUM> microns or greater, or the desired pore size could be in a range of <NUM> to <NUM>. Pores <NUM> that are sized <NUM> microns or less can function as a bacterial filter since the average diameter of spherical bacteria is <NUM>-<NUM>, and for rod-shaped or filamentous bacteria, the average length is <NUM>-<NUM> and the average diameter is <NUM>-<NUM>. In some applications, the first membrane <NUM> will have pores <NUM> sized larger than <NUM> microns and, in those circumstances, a separate filter (F shown with optional locations in <FIG>) may be provided to the gas source, gas supply line or the gas inlet of the gas diffuser device to filter out bacteria and other impurities.

First membrane <NUM> may have body portion <NUM> surrounded by edge portions <NUM>. Body portion <NUM> and edge portions <NUM> may all have pores <NUM>. The gas diffusion device <NUM> can include adhesive surfaces <NUM>, which may be covered by release paper. Adhesive surfaces <NUM> adhere to the patient's body surrounding the treatment site. Adhesive surfaces <NUM> could be an adhesive coating applied to the device or could be a separate film that is attached to or covers the device.

As seen in <FIG> and <FIG>, second membrane <NUM> may be made of any desired material and could be made from a polymer, a thin metal foil, surgical steel, leather and/ or any material that will hold its structural integrity during use and is capable of being sterilized. Second membrane <NUM> may be flexible or in some embodiments may not be flexible as to hold its shape during usage. The second membrane could also be made out of the same polymer as the first membrane <NUM>, such as a polytetrafluoroethylene and, more specifically, could be made of POREX® Virtek™ PTFE MD10. The second membrane may have any thickness as desired and could be <NUM>, and may also be hydrophobic and non-wetting. Second membrane <NUM> may be nonporous or substantially nonporous. The second membrane <NUM> may have a pore size smaller than the pore sizes (in some applications much smaller) of first membrane <NUM> and/or a bacterial efficiency rate that is greater than the bacterial efficiency rate of first membrane <NUM>, thereby directing the flow of gas through gas diffuser <NUM> and through first membrane <NUM> while preventing or decreasing (in some applications greatly decreasing) the escape or diffusion of gas through the second membrane. As such, the smaller pore size and/or the greater bacterial efficiency rate of second membrane <NUM> allows for the second membrane to be nonporous or substantially nonporous, as compared to first membrane <NUM>. In an optional embodiment, second membrane <NUM> may be made of a number of sheets or layers of a porous material that are bonded/adhered/affixed to one another to make the second membrane <NUM> less porous or substantially nonporous. In an alternative embodiment, second membrane may be made from the same material as first membrane <NUM> with a backing sheet affixed to it for stopping the flow of gas through second membrane <NUM> until such a time that the wound is required to breath or be observed. At this time the backing sheet can be removed and the wound can breath, be allowed to dry and be observed.

Second membrane <NUM> may have body portion <NUM> surrounded by edge portions <NUM>. Edge portions <NUM> of second membrane <NUM> are bonded/secured/adhered to edge portions <NUM> of first membrane by sonic welding, thermal welding, compression sealing, induction heating, adhesive or other processes known in the art. The bonding of outer edge portions <NUM> of the second membrane <NUM> to the outer edge portions <NUM> of the first membrane <NUM> form interior chamber <NUM> of the device. Second membrane <NUM> can prevent or inhibit gas introduced into the interior chamber from escaping. The second membrane <NUM> confines/directs the flow of the introduced gas in interior chamber <NUM> such that the introduced gas flows out or diffuses through the pores <NUM> of the first membrane <NUM> to the treatment site. Some sections of outer edge portions <NUM> of second membrane <NUM> and outer edge portions <NUM> of first membrane <NUM> are bonded/secured/adhered to portions of gas inlet <NUM> and optional flush line outlet or port <NUM>. The device <NUM> may include adhesive surfaces <NUM>, which may be covered by release paper and adhere to the patient's body surrounding the treatment site. Adhesive surfaces <NUM> can be an adhesive coating applied to the device or to either/both of the first and second membranes. Alternatively, adhesive surfaces <NUM> can also be a separate film that is attached to the device or to either/both of the first and second membranes.

Gas inlet <NUM> of device <NUM> can connect to the flexible gas hose (or other gas delivery means) and to the gas source through various means as known in the art. For example, a barbed or smooth push fitting could be used to connect the gas inlet to the gas supply hose for delivery of CO2 when it is deemed that the connection to the supply of gas should be connected for longer term care. Additionally, there is also the option of having quick disconnect fittings and screw fittings for supplying smaller durations of CO2 to the device that allow for easier/quicker disconnection of the gas delivery means. In order to maintain the therapeutic gas atmosphere along the treatment site and inside the device, the gas inlet may have a one way valve <NUM> to prevent gas that enters the device through gas inlet <NUM> from escaping back through the gas inlet. Alternatively/additionally, a Halkey-Roberts clamp, a plug, a cap or a tap could be used to prevent gas from escaping the device back through the gas inlet.

Optional flush line outlet or port <NUM> may be provided so that the gas delivered to the gas diffusion device can be flushed through the device, thereby removing gases/air, condensation, fluids or impurities that may exist at the treatment site and that may have built up within the device during use. The flush line outlet <NUM> may have a one way valve <NUM> to allow gas within the device to have a controlled exit or release from the device through the flush line outlet. The one way valve prevents any uncontrolled gas/air that is outside the device from entering into the device. Alternatively/additionally, a Halkey-Roberts clamp, a plug, a cap or a tap could be used to prevent gas from entering the device through the flush line outlet. The flush line outlet may have an option of having a three way tap on it. The open end of the purge line may have a female luer connection to allow a syringe to be attached when required to draw off any gas or fluid as required from the device and treatment site.

Gas diffuser device <NUM> may also have an overpressure relief valve <NUM> (optional) attached thereto allowing gas to be released or purged from the device when the pressure inside the device becomes too high and passes a desired threshold, thereby reducing the risk of damaging the device and potentially the treatment site.

Pore size of the flexible microporous polymer membrane can be determined using the Mercury Intrusion Method. In a vacuum, a mercury drop will not enter a pore due to its very high surface tension, but will if pressure is applied. It is known that, for a given pore size, a certain pressure is required to force the mercury into the pore. For each incremental increase in pressure, the change in intrusion volume is equal to the volume of the pores whose diameters fall within an interval that corresponds to the particular pressure interval. The amount of displaced mercury can therefore be used to calculate the pore size using a graphical representation. The pore size will be the average size of the pore distribution obtained (i.e. the peak value).

The Washburn Equation can be used to convert pressure to pore diameter: <MAT>.

For example, to arrive at a pore size in µm, y is <NUM> N/m, θ is in degrees, and P is the intrusion pressure, the pressure at which <NUM>% of the volume of mercury intrudes into the pores. The cumulative volume starts at zero and pressure is applied until no more mercury can be introduced (giving total volume of the pores at this point). In a typical test, a graph of cumulative volume (mm<NUM>/g) versus intrusion pressure (kPa) is made. The intrusion pressure is then read off the graph. This is the "<NUM>% value". It means that <NUM>% of the pores lie above this diameter and <NUM>% lie below it. Pore size in this application, including the claims, means this <NUM>% value, with <NUM>% of the pores being above this diameter and <NUM>% being below it.

The pores <NUM> of the microporous flexible polymer first membrane <NUM> allow the gas, preferably CO<NUM>, to diffuse over the full surface area of the membrane. The small pore size means that even at flows as low at <NUM> liters per minute (LPM) it will still act as a very efficient gas diffuser. The smaller pore size means in effect that the gas has to make more effort to exit the microporous flexible polymer first membrane <NUM> thereby flowing through more pores <NUM>. As such, an almost instantaneous therapeutic gas atmosphere can be formed along the treatment site once the gas is introduced through positive pressure to the gas diffusion device <NUM>. The introduced gas within the interior chamber of the gas diffusion device can have a higher velocity than the gas along the treatment site that has been diffused through the pores <NUM> of first membrane <NUM>. Thus the flow/diffusion of the introduced gas through the pores of the first membrane can create a slow, substantially laminar, gas flow whereby turbulence of the gas atmosphere is minimized.

<FIG> shows gas diffusion device <NUM> (in cross-section) in use for treating a wound W. Adhesion surfaces <NUM> are secured/affixed to the patient's body such that the device covers and surrounds the wound to be treated. Gas flows via positive pressure from gas source <NUM> through flexible hose <NUM>, through gas inlet <NUM>, and into interior chamber <NUM> of the gas diffusion device <NUM> (gas flow and diffusion across first membrane <NUM> shown with directional arrows). The gas, which may be carbon dioxide, flows out through the multiplicity of pores <NUM> of flexible, microporous polymer first membrane <NUM> (pores <NUM> are indicated in <FIG> but are too small to actually be seen) into the treatment site of the wound creating a gas atmosphere GA along the treatment site and wound. The gas may flow at any desired rate as to allow proper and adequate diffusion along the treatment site and could, for example, have a flow rate of greater than <NUM>/hr/cm<NUM> Δp 70mbar. In some embodiments, the gas (and other impurities) can be flushed out from the device through optional flush line outlet <NUM>. In some embodiments gas delivered to the device having a pressure higher than a desired threshold can be purged or released through optional overpressure valve <NUM>, thereby protecting the device and the wound from damage.

<FIG> shows gas diffusion device <NUM> in use for treating an open surgical site SS. Adhesion surfaces <NUM> are secured to the patient's body around open volume V and adjacent to a portion P of a human body that is normally not exposed to the atmosphere, as in a surgery. Gas flows via positive pressure from gas source <NUM> through flexible hose <NUM>, through gas inlet <NUM>, into interior chamber <NUM> of the gas diffusion device <NUM> (gas flow and diffusion across first membrane <NUM> shown with directional arrows). The gas, preferably carbon dioxide, flows out through the multiplicity of pores <NUM> of flexible, microporous polymer first membrane <NUM> (pores <NUM> are indicated in <FIG> but are too small to actually be seen) which fills the volume V forming a protective therapeutic gas atmosphere GA and preventing air A from the environment from reaching the volume. As CO2, the preferred gas, is heavier than air, the CO2 will accumulate in the volume V as long as the gas flow into the volume V is not turbulent. In some embodiments, the gas (and other impurities) can be flushed out from the device through optional flush line outlet <NUM>. In some embodiments gas delivered to the device having a pressure higher than a desired threshold can be purged or released through optional overpressure valve <NUM>, thereby protecting the device and the wound from damage.

In order to prevent air embolism, i.e., a blocking of the capillaries and small vessels which may be caused by an air bubble, the therapeutic gas atmosphere in a volume adjoining a temporarily, outwardly open portion of a human being ought to include a delivered gas, the majority of the gas being carbon dioxide. In the applications where a therapeutic gas atmosphere is to be created in a volume adjoining an outwardly open inner portion of the body of a human being or an animal, it is advantageous that the gas includes carbon dioxide due to the fact that carbon dioxide has a high solubility in the tissue of the body relative to oxygen and nitrogen and because carbon dioxide is heavier than air. It is to be noted that the gas may be supplied to the volume in a continuous flow, wherein it is possible to ensure that the surrounding air is prevented from reaching the volume even if a part of the supplied gas leaves the area. Another possibility is, at least initially, to supply gas continuously in order to create therapeutic gas atmosphere, and then supply gas periodically to maintain the gas atmosphere. It should also be noted that the gas may include oxygen, for instance in the cases when said tissue of said open body portion is strongly oxygen dependent. Oxygen, as well as carbon dioxide, is heavier than air so that the protecting atmosphere in the volume may be created in an easy manner since the heavier gas will pass downwardly in the open body portion and force away the non-sterile air present in the lower part of this open portion. In certain applications a protecting atmosphere including sterile air may be satisfactory. The main thing is that air from the environment, i.e., non-sterile air, is prevented from reaching the volume.

In one embodiment, the gas diffusion device will include a flexible shapeable gas delivery tube or hose extending from the gas inlet through the interior chamber of the gas diffusion device. The flexible, shapeable gas delivery tube includes multiple perforations or pores. The shapeable tube will allow the gas diffusion device to be shaped so that in certain instances it can surround the surgical site.

In one embodiment, the gas diffusion device will include shapeable structures within the first and second membranes and interior chamber which will allow the gas diffusion device to be molded around a surgical site in order to create the gas atmosphere.

In one embodiment, the microporous first membrane can also be coated in an antibacterial substance and also a medicated substance to aid healing and reduce pain and infections.

In one embodiment shown in <FIG>, the gas diffusion device will include an open cell sponge support material <NUM> positioned along the first membrane inside the interior chamber <NUM> of the device. The open cell sponge support material will aid the CO<NUM> gas in diffusing along the majority of the first membrane <NUM> and through pores <NUM>. In another embodiment the support material inside the interior chamber could have baking soda or another similar chemical compound impregnated into the support material <NUM> between the first and second membrane. An acidic fluid such as vinegar, rather than a gas could be supplied through the inlet of the device. The acidic fluid in contact with the baking soda or other similar compound causes a chemical reaction whereby carbon dioxide is created. The carbon dioxide is then diffused to the treatment site through pores <NUM> located in the microporous first membrane <NUM>.

Claim 1:
A device (<NUM>) arranged to deliver a gas to a treatment site, the device being connectable to a gas source (<NUM>), the device (<NUM>) comprising:
- a gas inlet (<NUM>) connectable to the gas source (<NUM>),
- a first membrane (<NUM>) comprising a flexible, hydrophobic, microporous polymer body (<NUM>), wherein the flexible, hydrophobic, microporous polymer body (<NUM>) has one of the following features:
(a) a pore size of <NUM> or less, or
(b) a pore size of <NUM> or greater, and
- a second membrane (<NUM>) comprising a flexible polymer body (<NUM>),
wherein when the flexible, hydrophobic, microporous polymer body of the first membrane (<NUM>) has feature (b) the gas inlet (<NUM>) has a bacterial filter (F),
wherein the first (<NUM>) and second (<NUM>) membranes each have outer edge portions (<NUM>, <NUM>) and the outer edge portions (<NUM>) of the second membrane are bonded to the outer edge portions (<NUM>) of the first membrane (<NUM>) to form an interior chamber (<NUM>) of the device (<NUM>), the interior chamber (<NUM>) of the device confining introduced gas to the interior chamber (<NUM>) such that the introduced gas flows out through pores (<NUM>) of the first membrane (<NUM>), the gas being introduced into the chamber (<NUM>) through the gas inlet (<NUM>) of the device (<NUM>),
wherein the flexible, hydrophobic, microporous polymer body of the first membrane (<NUM>) is arranged to diffuse the introduced gas into the treatment site and
wherein the introduced gas maintains a gas atmosphere along the treatment site.