referring now to fig1 a no delivery device 2 is shown connected to a patient 4 . in its most general sense , the no delivery device 2 includes a bathing unit 6 that is fluidically connected to a no gas source 8 , a flow control valve 22 , and a vacuum unit 10 . fig1 illustrates one preferred embodiment of the invention . in fig1 the no gas source 8 is a pressurized cylinder containing no gas . while the use of a pressurized cylinder is the preferably method of storing the no - containing gas source 8 , other storage and delivery means , such as a dedicated feed line ( wall supply ) can also be used . typically , the no gas source 8 is a mixture of n 2 and no . while n 2 is typically used to dilute the concentration of no within the pressurized cylinder , any inert gas can also be used . when the no gas source 8 is stored in a pressurized cylinder , it is preferable that the concentration of no in the pressurized cylinder fall within the range of about 800 ppm to about 1200 ppm . commercial nitric oxide manufacturers typically produce nitric oxide mixtures for medical use at around the 1000 ppm range . extremely high concentrations of no are undesirable because accidental leakage of no gas is more hazardous , and high partial pressures of no tends to cause the spontaneous degradation of no into nitrogen . pressurized cylinders containing low concentrations of no ( i . e ., less than 100 ppm no ) can also be used in accordance the device and method disclosed herein . of course , the lower the concentration of no used , the more often the pressurized cylinders will need replacement . fig1 also shows source of dilutent gas 14 as part of the no delivery device 2 that is used to dilute the concentration of no . the source of dilutent gas 14 can contain n 2 , o 2 , air , an inert gas , or a mixture of these gases . it is preferable to use a gas such as n 2 or an inert gas to dilute the no concentration since these gases will not oxidize the no into no 2 as would o 2 or air . the source of dilutent gas 14 is shown as being stored within a pressurized cylinder . while the use of a pressurized cylinder is shown in fig1 as the means for storing the source of dilutent gas 14 , other storage and delivery means , such as a dedicated feed line ( wall supply ) can also be used . the no gas from the no gas source 8 and the dilutent gas from the dilutent gas source 14 preferably pass through pressure regulators 16 to reduce the pressure of gas that is admitted to the no delivery device 2 . the respective gas streams pass via tubing 18 to an optional gas blender 20 . the gas blender 20 mixes the no gas and the dilutent gas to produce a no - containing gas that has a reduced concentration of no . preferably , the no - containing gas that is output from the gas blender 20 has a concentration that is less than about 200 ppm . even more preferably , the concentration of no - containing gas that is output from the gas blender 20 is less than about 100 ppm . the no - containing gas that is output from the gas blender 20 travels via tubing 18 to a flow control valve 22 . the flow control valve 22 can include , for example , a proportional control valve that opens ( or closes ) in a progressively increasing ( or decreasing if closing ) manner . as another example , the flow control valve 22 can include a mass flow controller . the flow control valve 22 controls the flow rate of the no - containing gas that is input to the bathing unit 6 . the no - containing gas leaves the flow control valve 22 via flexible tubing 24 . the flexible tubing 24 attaches to an inlet 26 in the bathing unit 6 . the inlet 26 might include an optional one way valve 64 ( see fig3 ) that prevents the backflow of gas into the tubing 24 . still referring to fig1 the bathing unit 6 is shown sealed against the skin surface of a patient 4 . the infected area 30 which can be an abscess , lesion , wound , or the like , is enclosed by the bathing unit 6 . the bathing unit 6 preferably includes a seal portion 32 that forms a substantially air - tight seal with the skin of the patient 4 . substantially air - tight is meant to indicate that the no - containing gas does not leak out of the bathing unit 6 in significant amounts ( i . e ., no more than about 5 % of the no - containing gas delivered to the bathing unit 6 ). the seal portion 32 may comprise an inflatable seal 61 , such as that shown in fig2 and 3 , or alternatively the seal portion 32 may comprise a flexible skirt or the like that conforms to the surface of the patient 4 . the seal portion 32 also might include an adhesive portion that adheres to the skin surface of a patient 4 . in other envisioned embodiments , the sealing portion 32 may merely comprise the interface of the bathing unit 6 with the surface of the patient &# 39 ; s 4 skin . the bathing unit 6 can be made of a virtually limitless number of shapes and materials depending on its intended use . the bathing unit 6 might be formed as a rigid structure , such as that shown in fig1 that is placed over the infected area 30 . alternatively , the bathing unit 6 can be formed of a flexible , bag - like material that is inflatable over the infected area 30 . fig2 shows such a structure in the shape of a boot that is placed over the patient &# 39 ; s 4 foot . fig3 shows another inflatable bathing unit 6 that is formed in the shape of a mitten or glove that is worn over the patient &# 39 ; s 4 hand . in one preferred embodiment of the invention , the bathing unit 6 includes an no sensor 34 that measures the concentration of no gas within the bathing unit 6 . the no sensor 34 preferably reports this information to a controller 36 via signal line 38 . an optional no 2 sensor 40 can also be included within the bathing unit 6 . the no 2 sensor 40 preferably reports the concentration of no 2 to the controller 36 via signal line 42 . the sensors 40 , 42 can be a chemilluminesence - type , electrochemical cell - type , or spectrophotometric - type sensor . the bathing unit 6 also includes an outlet 44 that is used to remove gas from the bathing unit 6 . the outlet 44 is preferably located away from the gas inlet 26 such that no gas does not quickly enter and exit the bathing unit 6 . preferably , the inlet 26 and outlet 44 are located in areas of the bathing unit 6 such that the no gas has a relatively long residence time . flexible tubing 46 is connected to the outlet 44 and provides a conduit for the removal of gases from the bathing unit 6 . in one preferred embodiment of the invention , the flexible tubing 46 is in fluid communication with an absorber unit 48 . the absorber unit 48 preferably absorbs or strips no from the gas stream that is exhausted from the bathing unit 6 . it is also preferable for the absorber unit 48 to also absorb or strip no 2 from the gas stream that is exhausted from the bathing unit 6 . since these gases are toxic at high levels , it is preferable that these components are removed from the delivery device 2 prior to the gas being vented to the atmosphere . in addition , these gases can react with the internal components of the vacuum unit 10 and interfere with the operation of the delivery device 2 . the now clean gas travels from the absorbing unit 48 to the vacuum unit 10 via tubing 50 . the vacuum unit 10 provides a negative pressure within the tubing 50 so as to extract gases from the bathing unit 6 . the vacuum unit 10 is preferably controllable with respect to the level of vacuum or suction supplied to the tubing 50 and bathing unit 6 . in this regard , in conjunction with the flow control valve 22 , the amount of no gas within the bathing unit 6 can be regulated . preferably , the vacuum unit 10 is coupled with the controller 36 via a signal line 52 . the controller 36 , as discussed below , preferably controls the level of output of the vacuum unit 10 . the gas then passes from the vacuum unit 10 to a vent 54 that is open to the atmosphere . it should be understood that the absorbing unit 48 is an optional component of the delivery device 2 . the gas laden with no and no 2 does not have to be removed from the gas stream if there is no concern with local levels of no and no 2 . for example , the gas can be exhausted to the outside environment where high concentrations of no and no 2 will not develop . alternatively , a recirculation system ( not shown ) might be used to recycle no within the bathing unit 6 . still referring to fig1 the delivery device 2 preferably includes a controller 36 that is capable of controlling the flow control valve 22 and the vacuum unit 10 . the controller 36 is preferably a microprocessor - based controller 36 that is connected to an input device 56 . the input device 56 is used by an operator to adjust various parameters of the delivery device such as no concentration , residence time of no , pressure within the bathing unit 6 , etc . an optional display 58 can also be connected with the controller 36 to display measured parameters and settings such as the set - point no concentration , the concentration of no within the bathing unit 6 , the concentration of no 2 within the bathing unit 6 , the flow rate of gas into the bathing unit 6 , the flow rate of gas out of the bathing unit 6 , the total time of delivery , and the like . the controller 36 preferably receives signals from sensors 34 , 40 regarding gas concentrations if such sensors 34 , 40 are present within the delivery device 2 . signal lines 60 , 52 are connected to the flow control valve 22 and vacuum unit 10 respectively for the delivery and receipt of control signals . in another embodiment of the invention , the controller 36 is eliminated entirely . in this regard , the flow rate of the gas into the bathing unit 6 and the flow rate of the gas out of the bathing unit 6 are pre - set or adjusted manually . for example , an operator can set a vacuum output that is substantially equal to the flow rate of the gas delivered to the bathing unit 6 via the flow control valve 22 . in this manner , no gas will be able to bathe the infected area 30 without any build - up or leaking of no or no 2 gas from the delivery device 2 . fig2 illustrates a bathing unit 6 in the shape of a boot that is used to treat an infected area 30 located on the leg of the patient 4 . the bathing unit 6 includes an inflatable seal 61 that surrounds the leg region to make a substantially air - tight seal with the skin of the patient 4 . this embodiment shows a nozzle 62 that is affixed near the inlet 26 of the bathing unit 6 . the nozzle 62 directs a jet of no gas onto the infected area 30 . the jet of gaseous no aids in penetrating the infected area 30 with no to kill or inhibit the growth of pathogens . fig3 shows another embodiment of the bathing unit 6 in the shape of a mitten or glove . the bathing unit 6 is also inflatable and contains an inflatable seal 61 that forms a substantially air - tight seal around the skin of the patient 4 . fig3 also shows an optional one way valve 64 located in the inlet 26 . as seen in fig3 and 4 , the inlet 26 and outlet 44 are located away from one another , and preferably on opposing sides of the treated area such that freshly delivered no gas is not prematurely withdrawn from the bathing unit 6 . for treatment of an infected area 30 , the bathing unit 6 is placed over the infected area 30 . an air - tight seal is then formed between the skin of the patient 4 and the bathing unit 6 . if the bathing unit 6 has an inflatable construction , the bathing unit 6 must be inflated with gas . preferably , the bathing unit 6 is initially inflated only with the dilutent gas to prevent the leaking of no and no 2 from the device 2 . once an adequate air - tight seal has been established , the operator of the device initiates the flow of no from the no gas source 8 to the bathing unit 6 . as described above , this may be accomplished manually or via the controller 36 . once the bathing unit 6 has started to fill with no gas , the vacuum unit 10 is turned on and adjusted to the appropriate output level . for an inflatable bathing unit 6 , the output level ( i . e ., flow rate ) of the vacuum unit 10 should be less than or equal to the flow rate of no gas entering the bathing unit 6 to avoid deflating the bathing unit 6 . in embodiments of the device where the bathing unit 6 is rigid , the vacuum unit 10 can be set to create a partial vacuum within the bathing unit 4 . in this regard , the partial vacuum helps to form the air - tight seal between the skin of the patient 4 and the bathing unit 6 . of course , the vacuum unit 10 can also be set to withdraw gas at a substantially equal rate as the gas is delivered to the bathing unit 6 . an effective amount of no is delivered to the bathing unit 6 to kill pathogens and / or reduce the growth rate of the pathogens in the infected area 30 . pathogens include bacteria , viruses , and fungi . fig4 shows another embodiment of the invention in which the bathing unit 6 includes an agitator 66 that is used to create turbulent conditions inside the bathing unit 6 . the agitator 66 preferably is a fan - type of mechanism but can include other means of creating turbulent conditions within the bathing unit 6 . the agitator 66 aids in refreshing the infected area 30 with a fresh supply of no gas . while embodiments of the present invention have been shown and described , various modifications may be made without departing from the scope of the invention . the invention , therefore , should not be limited , except to the following claims , and their equivalents .
a device for the topical delivery of nitric oxide gas to an infected area of skin includes a source of nitric oxide gas , a bathing unit , a flow control valve , and a vacuum unit . the bathing unit is adapted to surround the area of the infected skin and form a substantially air - tight seal with the skin surface . the bathing unit is also in fluidic communication with the source of nitric oxide . the flow control valve is positioned downstream of the source of nitric oxide and upstream of the bathing unit . the flow control valve controls the amount of nitric oxide gas that is delivered to the bathing unit . the vacuum unit is positioned downstream of the bathing unit and is used to withdraw gas from the bathing unit . application of nitric oxide gas to the infected area of skin reduces pathogen levels in the infected area and promotes the healing process .