Pressure controllable hyperbaric device

A method of treating a wound with therapeutic gas to expedite healing, and a topical hyperbaric device to carry out the method having a maximum pressure release valve that can be set a desired maximum treatment pressure and that is not connected to the gas supply.

BACKGROUND OF THE INVENTION 
Many difficult to heal wounds, particularly where there is damage to the 
blood circulation system, are now treated with a gas such as oxygen to 
supplement the oxygen to the wound area that is not being satisfied by the 
damaged blood circulation system. Initially, this was done by installing a 
gas chamber around the wound and flowing oxygen continuously over the 
wound area. These chambers were rigid, heavy, difficult to clean between 
uses, and uncomfortable for the patient. Recently it has been discovered 
that continuous flow of oxygen is not necessary, and that effective 
hyperbaric treatment can be obtained by using a single adequate stationary 
charge of oxygen that is retained in a flexible chamber in contact with 
the wound for the treatment period. Unlike the continuous flow type 
devices, these devices do not need to be continuously attached to the 
oxygen supply during treatment, allowing mobility for the patient. 
Many flexible topical hyperbaric bags are known. U.S. Pat. No. 5,154,697 
assigned to Topox, Inc. discloses a hyperbaric bag that has a hole through 
the side of the bag that is to be exposed to the area to be treated. The 
periphery of the hole is reinforced with a strong ring. A belt structure 
affixes the bag over the area to be treated, and gas such as oxygen 
inflates the bag to the desired gas pressure. The device contains a gas 
inlet for charging and a gas pressure release valve which is constructed 
for a fixed single maximum gas pressure. Unlike earlier hyperbaric 
devices, the device of this patent does not require a constant supply of 
gas. Although it is known that there are different narrow optimum 
pressures ranges for treating arterial wounds and venous wounds, the Topox 
bag is not designed to operate at a specific prescribed pressure. The 
devices cannot be adjusted to an optimum pressure in response to a wound 
diagnosis. 
Dyson-Cantwell U.S. Pat. No. 5,478,310 discloses a hyperbaric oxygen 
chamber for use on leg wounds. It comprises a polyethylene bag to be 
secured around the leg and ages supply line. This device does have a 
pressure control means but it is connected to the gas supply line. As 
shown in FIG. 3, the chamber may have a tape covering holes in the gas bag 
that can be pulled off the holes during treatment to decrease gas 
pressure. Using this device it is difficult, if at all possible, to set 
and maintain the treatment pressure within the range of desired treatment 
pressure. 
The prior art also discloses numerous topical hyperbaric devices that apply 
a continuous supply of gas flowing through the wound area. These of course 
require continuous connection to the gas supply, eliminating patient 
mobility during treatment. 
Some of these prior art continuous flow devices have pressure control 
valves that are connected to and control the gas input See Stivala U.S. 
Pat. No. 4,224,921; Tramell U.S. Pat. No. 5,029,479; and Frech U.S. Pat. 
No. 4,772,259. 
Pressure control means connected to the gas supply have several 
disadvantages. When the gas supply is disconnected or shut off the 
pressure control means is disconnected or shut off; and so the pressure 
control means is no longer functional. This is particularly important for 
devices designed for static treatment use. Also, accurate control of the 
treatment zone pressure is difficult because such valves are not directly 
measuring the treatment zone pressure. Furthermore, putting a pressure 
control valve in the gas supply line requires using an additional device, 
in addition to the gas cylinder or hospital gas supply line. In such a 
device the gas supply line cannot be directly connected to the hyperbaric 
treatment device treatment zone. 
SUMMARY OF THE INVENTION 
The present invention relates to a method of treating a patient's wound 
with a therapeutic gas to expedite healing, and hyperbaric treatment 
devices for practicing this method. 
The method of the present invention comprises: diagnosing the wound to 
determine a treatment zone desired maximum gas pressure; selecting a 
hyperbaric treatment device capable of receiving the therapeutic gas from 
a gas supply, which device has a means not in direct communication with 
the gas supply to set the maximum treatment zone gas pressure; setting 
this means at the desired maximum gas pressure; affixing the device 
encompassing the wound to make a treatment zone including the wound, 
within which zone the gas is restricted; and introducing sufficient 
therapeutic gas into the treatment zone to substantially maintain the gas 
pressure therein at the desired maximum pressure. This treatment is 
continued for the prescribed duration and repeated at the prescribed 
intervals, determined by the diagnosis. Preferably the treatment is a 
static charge treatment, wherein the gas is retained in the treatment zone 
for a prolonged period of time so that the gas supply can be disconnected 
giving patient comfort. 
The topical hyperbaric devices of the present invention are ideally suited 
to carry out the method of this invention. This device comprises a 
flexible substantially gas impermeable sheet of material that is capable 
of confining the therapeutic gas to a restricted therapeutic gas treatment 
zone; means to affix the material to make a restricted therapeutic gas 
treatment zone encompassing the wound, wherein the gas is kept in contact 
with the wound and is restricted from escaping from the treatment zone; 
means for introducing the therapeutic gas into the treatment zone; and a 
pressure release valve capable of setting the maximum gas pressure of the 
treatment zone to the desired treatment pressure, which valve is not in 
direct communication with the mean for introducing the gas. The valve 
automatically releases gas from the treatment zone when the maximum 
pressure is exceeded, which pressure can be pre-set at the desired maximum 
pressure in the zone. Preferably the valve is manually adjustable so that 
the desired maximum pressure of the treatment zone can be set accurately 
at the appropriate gas pressure determined by diagnosis.

DEFINITIONS 
The term "gram gas pressure" means the not-to-be exceeded highest gas 
pressure. 
The term "optimum gas pressure" means the most effective therapeutic gas 
treatment pressure for achieving desired healing. 
The term "desired maximum gas pressure" means the highest gas pressure to 
be used in a particular treatment. It may be the exact pressure prescribed 
from the diagnosis, or it may be somewhat higher than the prescribed 
pressure to achieve an average of close to the prescribed pressure during 
treatment In continuous flow treatment, the "desired maximum gas pressure" 
normally is the prescribed pressure. 
The term "substantially maintain the gas pressure", as used herein in 
reference to the treatment zone gas pressure, means the gas pressure is 
maintained close to the desired gas pressure by restricting escape of gas 
and/or adding gas during treatment. "Substantially" means to include 
deviation from the precise desired maximum gas pressure; this deviation 
may be as much as 30% or more so long as the deviation is not too much for 
adequate treatment in the particular case. 
The term "retained", as used herein with respect to gas in the treatment 
zone, means the gas is kept in the treatment zone (static treatment, not 
continuous flow treatment). "Substantially retained" refers to the normal 
situation in static treatment wherein some gas leakage is expected, 
possibly requiring period replenishment. 
The term "restricted", as used in reference to the treatment zone gas, 
means excessive uncontrolled escape of gas from the treatment zone is 
prevented. In static treatment, optimally "restricted" and "retained" mean 
completely prevented from escaping. Of course this level of restriction is 
seldom, if ever achieved, and so the term "restricted" is intended to 
include substantial gas escape so long as adequate therapeutic gas is 
maintained in the treatment zone. "Restricted" also applies to continuous 
flow treatment, where gas is continuously fed and exited from the 
treatment in a controlled manner while maintaining treatment zone 
pressure; uncontrolled escape of gas is minimized. 
The term "substantially gas impermeable", as used herein with respect to 
the sheet material, means gas impermeable to the extend needed to prevent 
excessive gas escape from the treatment zone through the sheet material. 
Total gas impermeability seldom is needed, particularly for continuous 
flow treatment devices. However, generally high impermeability is 
desirable for static treatment devices. 
The term "continuous flow treatment" means treatment during which gas is 
substantially continuously added and exited through most of the treatment 
period. It may include periods when the gas supply pressure is decreased, 
allowing treatment at a lower pressure, but the gas supply remains 
connected. 
The term "static treatment" means treatment during which an initial charge 
of gas is retained in the treatment zone for a prolonged treatment time 
period, and there is no continuous flow of gas to the treatment zone 
during treatment. In static treatment, intermittent gas additions may be 
needed during the treatment period to replace escaped gas and maintain gas 
pressure. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
To practice the method of the present invention, before treatment the wound 
is diagnosed to determine whether arterial or venous and the desired 
maximum treatment gas pressure, duration and sequence of treatments. 
Normally, if the wound is arterial an optimum treatment pressure in the 
range of about 25-35 mm Hg, and if venous a desired pressure in the range 
of about 15-20 mm Hg, is therapeutically optimal. Typically a 7 day 
treatment period is prescribed comprising identical one to two hour 
treatments on days 1, 2, 3 and 4, followed by no treatment on days 5 thru 
7, which treatment usually is repeated one or more times. 
An appropriate topical hyperbaric device capable of receiving gas from a 
gas supply source is then selected. This device comprises a means not in 
direct communication with the gas supply to accurately set the maximum 
treatment zone gas pressure at the desired maximum pressure determined by 
the diagnosis. This desired maximum pressure will be set to give an 
average treatment pressure, usually within the optimum ranges set forth 
above. The desired maximum pressure setting is achieved either by 
selecting a release pressure valve that is fixed at the appropriate 
desired maximum pressure, or using a hyperbaric treatment device having a 
manually adjustable maximum pressure valve and manually setting it at the 
desired maximum pressure. 
The topical hyperbaric treatment device is then affixed to the patient to 
encompass the wound and make a treatment zone including the wound, into 
which gas is introduced and restricted from escaping. Sufficient 
therapeutic gas is then introduced into the treatment zone to maintain the 
gas pressure therein substantially at the desired maximum pressure. If a 
preferred static pressure device is being used, it will retain a single 
static gas charge for a prolonged period of time, the duration of which 
depends on how well the device is able to restrict the gas and retain it 
in the treatment zone. Some times it is necessary to add gas periodically 
to substantially maintain the desired maximum pressure. When gas is added, 
addition is continued until the pressure release valve starts to release 
gas, indication that the desired maximum pressure in the treatment zone 
has been reached. The need for additional gas can be noted by observing 
diminished volume in the treatment zone, i.e. a softening or flattening 
bag. Alternatively the device may have a pressure gauge connected to the 
treatment zone. 
The present invention product is a flexible pressure controllable topical 
hyperbaric device for treating wounds and lesions with a therapeutic gas, 
particularly oxygen. The device comprises a flexible substantially gas 
impermeable sheet material capable of applying and confining a gas to the 
therapeutic treatment zone, including the area of the wound to be treated; 
means to deliver gas to said area; and at least one maximum pressure 
release valve means that is in direct communication with the treatment 
zone but is not in direct communication with the gas supply. Preferably a 
manually adjustable release valve means is used because such a valve means 
can be set easily and accurately before use to whatever desired maximum 
gas pressure is prescribed, insuring the correct pressure for the 
particular treatment. For example, when treating arterial wounds average 
treatment pressures in the range of 25-35 mm Hg above atmospheric are 
optimum whereas when treating venial wounds pressures in the range of 
about 15-20 mm Hg are optimum. A standardized hyperbaric treatment device 
having a manually adjustable pressure release valve means can be used for 
whatever desired maximum pressure is prescribed. Desirably the valve means 
can be set accurately (either by an adjustable valve or by selecting the 
appropriate fixed pressure release valve element) accurately within the 
range of about 3 to 60 mm Hg., with an accuracy of about 10 mm Hg., 
preferably 5 mm Hg. 
Referring to FIGS. 1 and 2, a preferred static treatment device 10 of the 
present invention comprises a sheet of flexible gas impermeable sheet 
material 11 and 12 that is capable of confining gas and retaining it in a 
restricted therapeutic gas treatment zone. The confining sheet material 
has a wound access opening 13, which in use is placed circumferentially 
over the wound. As shown here, opening 13 is defined by reinforcing ring 
18 of strong flexible material capable of fitting to the contour of the 
wound periphery. Preferably the skin contact side of ring 18 is coated 
with a layer of adhesive. The wound, around which ring 18 is securely 
affixed by adhesive or pressure from a belt, and the gas pouch 14 of 
device 10 define a restricted therapeutic treatment zone encompassing the 
wound, wherein therapeutic gas is retained in contact with the wound and 
is restricted from escaping. In this device, gas inlet tube 15 has a one 
way valve that permits intermittent addition of gas, but not escape 
thereof. This fitting is adapted to connect directly with the gas supply. 
Maximum pressure release valve 17 is in direct communication with the 
treatment zone; it is not in direct communication with the gas supply. As 
a desirable option, there may be a pressure gauge (nor shown) in 
communication with gas pouch 14 which shows the treatment zone gas 
pressure. If so, a single unit comprising the maximum pressure valve and 
the pressure gauge is preferred, although separate units can be used. 
FIG. 3 schematically shows a manually adjustable pressure release valve 17. 
This is a screw top valve that increases the treatment zone maximum 
pressure as screw 29 is screwed down. It comprises plastic cylindrical 
housing 21 that has an internal shoulder 22 at the bottom end with an 
opening 23 therein. Valve ball 24 seats on shoulder 22 sealing opening 23 
closed. Tension spring 25 fits snugly above ball 24 along the inner sides 
of housing 21, and exerts the selected release pressure on ball 24. Spring 
25 is designed to be able to exert about 5-60 mm Hg on ball 25. Screw top 
29 is threaded into the top of housing 21 so that it's plunger end abuts 
the top of spring 25. As screw 26 is screwed in it compresses spring 25, 
increasing the pressure on ball 24. When the pressure in the treatment 
zone exceeds the force of spring 25, ball 24 moves upward in the chamber 
of housing 21, allowing gas to escape from the treatment zone through 
opening 23 into the chamber of housing 21 and out through exhaust port 26. 
Referring to FIG. 4, the pressure release valve need not be adjustable. 
Instead the valve may be a fixed release pressure female element that is 
easily inserted or screwed into a male receptacle in communication with 
the treatment zone. This device also comprises opening 23, ball 24, spring 
25 and exhaust port 26 which function the same as there counterparts of 
FIG. 3. A selection of such fixed pressure release elements is made 
available, from which an element having the desired maximum release 
pressure setting is selected. These elements may be color coded to 
indicate their release pressure. When a fixed pressure release valve is 
used, the need for a pressure gauge is small. 
The design of the pressure release valve is not critical. Many different 
types are suitable. For example, instead of a ball valve as shown in FIGS. 
3 and 4, the release valve can be a baffle valve such as a flap or 
butterfly baffle valve. Other valves are equally suitable, so long as they 
are capable of accurately setting the maximum release pressure and are 
inexpensive and so discardable. If desired the adjustable valve can be 
calibrated to show the pressure setting. The preferred valve bodies are 
made of any rigid plastic, although metals such as stainless steel can be 
used. The spring preferably is steel. Very inexpensive completely plastic 
valves can be used. 
The pressure release valves of FIGS. 3 and 4 are inexpensive yet reliably 
accurate, within the preferred accuracy ranges. If desired, they can be 
removed from the hyperbaric treatment device when the device is being 
cleaned between applications. The entire hyperbaric treatment device, 
including the valve, is inexpensive and disposable. Using a valve that is 
in communication with the treatment zone and not with the gas supply 
eliminates the need for a separate pressure control mechanism between the 
hyperbaric treatment device and the oxygen source. The hyperbaric device 
can be connected directly to the gas cylinder or hospital gas supply line. 
The material from which the flexible sheet is made can be any strong 
substantially gas impermeable material. Cast plastic sheeting material, 
such as polyurethane, polyethylene terephthalate, polyvinyl chloride, or 
ethylene/polyvinyl copolymer sheet stock, and vapor proof treated fabric 
such as nylon are suitable. For many uses it is desirable that the sheet 
material be transparent. The flexible sheet material can have a variety of 
shapes. It is a rectangular two sided envelope configuration in FIGS. 1 
and 2. It can be a single layer, such as a bag to surround a limb. Or it 
can be a double layer cuff to go around a limb. For wounds on the back or 
buttocks, the rectangular envelope is best suited. 
These devices of FIGS. 1-4 are used in the preferred static treatment 
method of the present invention to treat wounds that need hyperbaric 
therapeutic gas treatment, particularly with oxygen. It is known that for 
optimum treatment "the pressure of oxygen is regulated to be between 
approximately 25-30 mm Hg for arterial injuries, burns and pyoderma 
gangrenosum and preferably between 18-20 mm Hg for venous ulcers" (U.S. 
Pat. No. 5,478,310, Col 3, lines 65 et seq.). The method of the present 
invention for treating a wound with a therapeutic gas is carried out using 
the device of FIGS. 1 and 2 by affixing the gas treatment opening over the 
wound and securely affixing or adhering it to the patient out of contact 
with the wound. The pressure release valve is set at the prescribed 
desired treatment pressure determined by diagnosis, normally slightly 
above the optimum treatment gas pressure. A charge of oxygen is then fed 
to the device though the gas inlet tube. If the device has a pressure 
gauge, the gas is introduced until the gas pressure gauge shows a pressure 
slightly above the desired treatment pressure. The pressure release valve 
is then turned to adjust the pressure lower until the desired maximum gas 
pressure level is stabilized. If there is no pressure gauge, the pressure 
release valve is set at the desired maximum release pressure and gas is 
introduced until the valve is activated, showing that the treatment zone 
has been charged to the desired maximum gas pressure. The gas supply then 
may be disconnected so that the patient has mobility. The device restricts 
and confines the gas, restraining it within the treatment zone and 
substantially maintaining pressure at the desired level for a prolonged 
period of time from the initial gas charge. Nevertheless, as the treatment 
continues, usually gas will need to be added to replace leaked gas. This 
is readily done by re-attaching the gas supply and adding gas as 
necessary. 
If a continuous gas flow treatment is prescribed, a continuous treatment 
hyperbaric device is used. It is similar to the device of FIGS. 1 and 2, 
except that it also has a gas outlet port or tube. The gas supply remains 
attached during the treatment, and supplies a flow of gas substantially 
continuously throughout treatment. The gas flows across the wound and 
exits out of the treatment zone through the outlet port. The rate of feed 
of the gas depends on the size of the outlet port, and is sufficient to 
substantially maintain the desired treatment pressure. More constant 
treatment zone gas pressure may be attainable using a continuous treatment 
hyperbaric device. 
Although the invention herein has been described with references to 
particular embodiments, it is to be understood that the embodiments are 
merely illustrative of the principles and applications of the present 
invention. It is therefore to be understood that numerous modifications 
may be made to the embodiments and that other arrangements may be devised 
without departing from the spirit of the present invention as defined by 
the claims.