Abstract:
A head enclosing gas hood for treating respiratory ailments is placeable over a patient&#39;s head for providing a gas, preferably oxygenated, to said patient. The treatment gas hood has a hood portion which is connected to a hood ring. The hood ring slides over a two-piece neck ring, the two-piece neck ring consisting of an upper neck ring and a lower neck ring retained in adjacent relationship. The hood ring slides over the two-piece neck ring and forms a sealing relationship therewith. The two-piece neck ring has a neck seal retained therein and has a sealing ring on the outer periphery thereof for engagement with the working surface of the hood ring. Ports may be provided for directing a flow of a gas into and from the interior portion of the hood where the individual&#39;s head is located. The neck seal provides an adequate seal between the neck ring and the individual&#39;s neck such that a pressurized environment may be created in the hood if desired. The hood may also be used to create a local environment different from ambient, such as rich in oxygen for the patient to breathe without pressurizing the hood. The two-piece neck ring may also have a retaining ring for holding the neck seal in place after the upper and lower neck rings are retained together.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. Ser. No. 09/855,378 filed on May 15, 2001, now abandoned which is a continuation-in-part of U.S. Ser. No. 09/585,970 filed on Jun. 2, 2000 now U.S. Pat. No. 6,701,920. 

   FIELD OF THE INVENTION 
   This invention relates to a head enclosing gas hood for covering of a person&#39;s head for treating respiratory ailments. 
   BACKGROUND OF THE INVENTION 
   A variety of head enclosing treatment hoods have been developed for use in the delivery of gas, including oxygen, to the wearer. Such a delivery system may be desirable for directing clean air or other gases into the hood for breathing by the wearer. This function is also desirable in use as a hyperbaric oxygen treatment system wherein the patient is exposed to increased barometric pressure inside a decompression chamber, while wearing the hood device and receiving an oxygen rich environment. It may be desirable to have such a head enclosing treatment hood wherein the hood is transparent so the wearer can see outside of the device and so that an adequate seal is provided between the wearer and the enclosing treatment hood. 
   In many different instances, patients must have their entire head enclosed in a treatment hood or wearing an aerosol mask device to receive the prescribed pressurized air or gas treatment. It is therefor desirable to have the transparent hood surrounding the patient&#39;s head and also having an efficient assembly for connecting the hood with a neck ring and a neck seal forming a seal around the patient&#39;s neck and allowing the hood area of the device to be filled with the treatment gas, often times pressurized. It is therefor essential that an adequate seal be made between the hood and the hood ring retaining the hood as well as between the hood ring and the neck ring and neck seal. 
   Various hoods are disclosed in the prior art including U.S. Pat. No. 5,226,409, U.S. Pat. No. 4,620,538 and U.S. Pat. No. 5,819,728. In all of these prior art devices, various hood and neck ring assemblies are disclosed. However, in these designs, there is no teaching of a simplified sealing and connection-system between the hood ring and the neck ring and neck seal. Some of the devices disclosed in the above-referenced patent have complex or difficult structures to ensure sealing between the neck ring and neck seal and also include structure which does not readily retain the proper pressure within the hood. It is also found in these prior art devices that after repeated wear on various surfaces of the devices, the seal between the hood and the hood ring may be corrupted. It is further noted that the prior art devices include complex or difficult attachment processes for affixing the neck seal to the neck ring or in assembly of the device. All of these shortcomings are resolved by the design of the head enclosing gas hood of the present invention. 
   Moreover, in the treatment of respiratory ailments, performed outside a pressurized environment, masks which are placed over the nose and mouth with elevated air flow rates have become widely acceptable. However, theses masks have been found to be extremely uncomfortable by the respiratory patient, resulting in a decreased compliance with the prescribed treatment regimen. 
   SUMMARY OF THE INVENTION 
   It is therefor an object of the present invention to provide a head enclosing treatment hood wherein the hood seal is attached to a hood ring. 
   It is a further object of the present invention to provide a neck ring wherein the hood ring seal is engaged with the neck ring and the neck ring further contains a neck seal which adequately seals around a patient&#39;s neck. 
   An additional object of the present invention is to provide a two-piece neck ring for attachment and retaining of the neck seal. 
   It is a further object of the present invention to provide a neck seal which is attached to the neck ring and which does not require the end user to perform an assembly step and wherein the neck seal may be securely retained within the two-piece neck ring upon shipment by the manufacturer. 
   A further object of the present invention is to provide a novel hood ring design wherein the attachment point between the hood and the hood ring is not located on a working and sealing surface between the hood ring and the neck ring. 
   An additional object of the present invention is to provide a device port through the neck ring allowing monitoring devices to be inserted into the interior portion of the gas treatment hood of the head enclosing gas hood. 
   An even further object of the present invention is to provide a two-piece neck ring wherein the upper and lower pieces of the neck ring may be pre-assembled and wherein the neck seal, in this pre-assembly step, is firmly retained in between the upper and lower neck rings. 
   Another object of the present invention is to provide a method for treating respiratory ailments with the use of a pressurized treatment hood. 
   These and other objects are resolved by the design of the head enclosing gas treatment hood of the present invention. The head enclosing gas treatment hood of the present invention is comprised of a hood which is affixed to a hood ring, the affixation point of the hood to the hood ring placed somewhere on the non-working surface of the hood ring. The hood ring slides over a neck ring in sealing engagement thereto. The neck ring of the present invention is a novel two-piece neck ring which has the neck seal compressed in between the upper neck ring and the lower neck ring in such a manner as to provide a sealing relationship to the interior of the hood and around the user&#39;s head. The upper and lower neck ring have both a retaining O-ring and a sealing O-ring secured firmly therebetween both of which act to either retain the neck seal or firmly seal the upper and lower neck rings with the hood ring. The head enclosing gas hood of the present invention also includes a neck seal which, as discussed above, is retained between the upper neck ring and lower neck ring and which extends inwardly from the neck ring. The neck seal is made of a gas impermeable material and stretches around the users neck to seal the interior portion of the hood and allow the interior portion to be filled with the supplied gas. 
   One advantage of the present design is that the upper and lower neck ring may be assembled easily with the neck seal compressed therebetween. Thus, the prior art designs which require assembly of the neck ring by stretching or by retention in specially constructed rings is overcome with a simplified design which compresses the seal between the neck ring pieces. 
   The present invention also provides a method for treating respiratory conditions which includes placing a hood over the head of a user wherein the hood is of a flexible gas impervious transparent material with the neck seal around an opening through which the head is inserted. Furthermore, the hood is in flow communication with a pressurized gas supply source. The hood is then sealed around the user&#39;s neck and the hood is pressurized with the gas from the pressurized supply source. An exit exhaust port is left open to provide removal of the expelled gases by the user. 
   All of the above outlined objectives are to be understood as exemplary only and many more objectives of the invention may be gleaned from the disclosure herein. Therefore, no limiting interpretation of the objectives noted are to be understood without further reading of the entire specification and drawings included herewith. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The head enclosing gas hood of the present invention will be more clearly understood by reference to the following detailed description and of the preferred embodiment thereof in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a perspective view of the head enclosing gas hood of the present invention; 
       FIG. 2  is a sectional view of the head enclosing gas hood of the present invention; 
       FIG. 3  is an exploded view of the two-piece neck ring of  FIG. 1 ; 
       FIG. 4  is a partial sectional view of the assembled two-piece neck ring and neck seal of the present invention; 
       FIG. 5  is a close-up perspective view of the upper neck ring of the present invention; 
       FIG. 6  is a perspective sectional view of the hood ring and hood of the present invention; 
       FIG. 7  is a close up sectional view of an alternative embodiment of the hood ring and neck ring of the present invention; 
       FIG. 8  is a close up sectional view of an alternative embodiment of the hood ring and neck ring of the present invention with the neck ring attached thereto. 
       FIG. 9  is a perspective view of a preferred embodiment of the present invention for respiratory ailments in a use condition; 
       FIG. 10  is a perspective view of a hood ring used in  FIG. 9 ; 
       FIG. 11  is a perspective view of a holding clip used in  FIG. 9 ; 
       FIG. 12  is a sectional view in detail of the assembly of a gas hood of  FIG. 9 ; 
       FIG. 13  is a partial sectional view of an assembled gas hood without the transparent hood; 
       FIG. 14  is a perspective view of the bottom side of the lower neck ring; 
       FIG. 15  is a perspective view of the bottom side of the upper neck ring; 
       FIG. 16  is a perspective view of an assembled gas hood without the transparent hood; 
       FIG. 17  is a partial sectional view of another embodiment of an assembled gas hood without the transparent hood; and 
       FIG. 18  is a perspective view of another embodiment of the head enclosing gas hood of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The head enclosing treatment hood of the present invention is shown in FIG.  1 . As disclosed therein, the gas hood or head tent  10  is comprised of hood portion  12  which is affixed to a hood ring  15 . The hood ring slides aver the upper neck ring  46  and lower neck ring  48 . Upper and lower rings  46  and  48  have a neck seal  20  compressed therebetween, the neck seal  20  extending inwardly therefrom. Neck seal  20  is provided so that a gas impermeable seal may be made between the hood ring  15  and upper and lower neck rings  46  and  48  and the user&#39;s neck when the user&#39;s head is inserted into the hood portion  12 . First gas port  41  and second gas port  42  are also provided for insertion and removal of gas from within the hood portion  12 . First gas port  41  and second gas port  42  extend through the upper neck ring  46  and lower neck ring  48  so that ready access is provided into the interior of the hood portion  12 .  FIG. 9  shows the gas hood  10  placed over the head of a user  200 . 
   The gas hood or head tent  10  of the present invention may be utilized to provide an atmosphere for medical treatment or for the simple supply of oxygen or other gases to a patient. The patient may slide the two-piece neck ring  40  as is shown in  FIG. 4 , and the neck seal  20  over their head such that the individual&#39;s head is inserted into the interior of hood  12 . The head tent  10  of the present invention thereby seals off the individual&#39;s head by providing access to the interior of the hood only through the first and second gas ports  41  and  42 . A sealing relationship exists between the hood  12  and hood ring  15  and between the hood ring  15  and the two-piece neck ring  40 . Further, the neck seal  20  is sealingly engaged between the upper and lower neck ring  46  and  48  while the neck seal  20  and the hood  12  are made of a gas impermeable material. Thus, for treatment of a patient in need of a controlled specialized environment or in need of a pure oxygen, higher oxygen content breathable air, or other gas mixtures the user may slide the head tent or gas hood  10  of the present invention over their head and a supply line of the gas is placed in flow communication with the interior of hood  12  through first gas port  41 . Second gas port  42  may then be utilized to provide an exit flow port of the gas contained therein. By regulating the amount of gas entering and exiting the hood, a positive pressure can be maintained. A preferred range of 5-30 cm H 2 O pressure within the hood works best for most therapies. 
   A two-piece neck ring assembly  40  as is disclosed herein is comprised of an upper neck ring  46  and a lower neck ring  48  and provides advantages for assembly of neck seal  20  in that a secure and tight seal is guaranteed between the neck seal  20  and the two-piece neck ring  40 . 
   One important aspect of the present invention is shown in FIG.  2  and in  FIG. 4 , wherein the two-piece neck ring  40  of the present invention is shown. The two-piece neck ring  40  of the present invention is comprised of an upper neck ring  46  and a lower neck ring  48  which compresses therebetween neck seal  20 . Thus, upon manufacturing of the upper and lower neck rings  46  and  48  the neck seal  20  may be assembled therebetween and the two-pieces may be sealingly engaged to each other. 
   As is shown in FIG.  2  and in  FIG. 4 , the two-piece neck ring  40  is comprised of the upper neck ring and lower neck ring  46  and  48  as well as a retaining O-ring  36  and a sealing O-ring  38 . The retaining O-ring  36  may be compressed between the upper and lower neck rings  46  and  48  in order to hold the neck seal  20  in place. Retaining ring  36  may be placed in an interior groove of the upper neck ring  46  and the neck seal  20  may be held in place by retaining ridge  45  which extends upwardly from the lower neck ring  48 . 
   Alternatively, as shown in  FIG. 13 , retaining O-ring  36  may be eliminated and instead the end of neck seal  20  is rolled into a ring  37  and inserted into the space formerly occupied by retaining O-ring  36 . Neck seal ring  37  may be adhesively bonded to neck seal  20  so as to retain its form, or when placed between upper neck ring  46  and lower neck ring  48  retain its shape by compression. Neck seal ring  37  functions identically to retaining O-ring  36  in that neck seal  20  is held in place and a gas-tight seal formed. Retaining ridge  45  may or may not be necessary to assist in the retention of neck seal  20 , depending on the circumference of neck seal ring  37 . 
   As is shown in  FIG. 4 , the neck seal periphery  22  of the neck seal  20  may be inserted into the interior portion of the two-piece neck ring  40  and may be retained in place by passing it under retaining ring  36  which will work in conjunction with retaining ridge  45  of the lower neck ring  48 . Another embodiment for retaining the neck seal  20  between the upper neck ring  46  and lower neck ring  48  is shown in FIG.  17 . The neck seal periphery  22  is passed over the retaining O-ring  36  rather than beneath it. Retaining ridge  45  functions to push retaining O-ring  36  tighter against upper neck ring  46 , securely clamping the end of neck seal  20  onto the two-piece neck ring  40 . The neck seal periphery  22  is thus placed into the interior of the upper and lower neck ring  46  and  48  and is held in place by the compressive forces of the two rings in combination with retaining ring  36 . An additional sealing ring  38  may be provided on the exterior periphery of the two-piece neck ring  40  and placed in between upper neck ring edge  49  and lower neck ring edge  44  as is shown in FIG.  4 . Thus, upon assembly of the two-piece neck ring  40 , a slight gap will extend vertically between the upper neck ring edge  49  and lower neck ring edge  44  which receives the sealing ring  38 . The sealing ring  38  extends slightly outward from the peripheral edge of ring  40  and may then provide a proper seal between the two-piece neck ring  40  and the hood ring  15  as is shown in FIG.  2 . 
   In addition to the sealing structure noted above, the first gas port  41  and second gas port  42  are provided in the two-piece neck ring  40 . First and second gas port  41  and  42  are cylindrical members which extend upwardly and downwardly from upper neck ring  46 . Lower neck ring  48  has apertures of similar size to the diameter of the first and second gas ports  41  and  42  such that upon assembly of the two-piece neck ring  40 , the downwardly extending portion of the ports  41  and  42  may extend through said apertures  31  and  32 , shown in FIG.  3 . Thus, both the upper and lower neck rings  46  and  48  may be designed to have an aperture which are coaligned and which extend into the interior of the hood  12 . As shown in  FIG. 13 , first and second gas ports  41  and  42  each may be covered with a gas port cap  140  when not in use. Or, when a pressure increase is desired on the interior of the hood  10 , one cap  140  can be left on gas port  41  or  42  and removed from the other. 
   Additionally, a device port  43  may be provided in both the upper neck ring  46  and lower neck ring  48  such that a monitoring device or other instrument may be inserted through two-piece neck ring  40  and into the interior of the hood  12 . As previously indicated, first and second gas ports  41  and  42  provide a flow way into and out of the hood  12 . Thus, a gas supply line may be affixed to the lower portion of the first gas port allowing a flow of fresh gas into the interior of hood  12 . Second gas port  42  may then be utilized as an exit port for removal of the gas. A monitoring device may be inserted through the device port aperture  43  allowing the gas within hood  12  to be monitored. Further, a device port closure  143  may be provided which seals the device port aperture when it is not needed. An exemplary device port closure  143  is shown in FIG.  13 . This closure  143  is conical shaped with gradations  144  evenly space along its length. The gradations  144  may be used as a guide to evenly cut off the end of the closure  143  at a desired point. The further down the closure  143  is cut, the larger the diameter of the opening created through the closure  143 . Thus, a tight seal can be maintained around a monitoring device regardless of the size of the device. 
   As can be seen from  FIG. 2 , the assembled upper and lower neck rings  46  and  48  retain the neck seal  20  in sealing relationship and allow the hood ring  15  to slide thereover. As can be seen, hood ring  15  for example, may be an inverted L-shaped ring with the hood  12  sealingly attached thereto. Alternative designs however are available and are within the scope of this teaching. The hood ring slides over the assembled upper and lower neck rings  46  and  48  allowing the sealing ring  38  to engage the hood ring working surface  17 , as shown in FIG.  6 . As shown in  FIG. 2 , a slight spacing in between the sealing ring  38  and the hood ring is depicted for ease of discussion. However, in actual use, the hood ring will sealingly engage the hood ring  15  to provide a gas impermeable connection between the hood ring  15  and upper and lower neck rings  46  and  48 . 
   Turning to  FIG. 3 , the two-piece neck ring  40  of the present invention is shown in an exploded view. The two-piece neck ring  40  is comprised of upper neck ring  46  and lower neck ring  48 . Also shown therein are the cylindrical first gas port  41  and second gas port  42 . Device port  43  is provided for access into the interior of hood  12 . The ports  41  and  42  as depicted are cylindrical in design, but any shape may be utilized as long as a gas flow may be provided through the neck ring  40 . Also as is shown in  FIG. 3 , first access aperture  31  and second access aperture  32  are provided such that the lower extending portion of the ports  41  and  42  may extend downward through the lower neck ring  48  and be readily accessible. Also shown in  FIG. 3  is the third access aperture  33  through which the device port  43  may be utilized. Not shown in  FIG. 3  is the retaining ring  36  and the sealing ring  38  which are compressed between the upper neck ring and lower neck ring  46  and  48  upon assembly. 
   The upper neck ring  46  and lower neck ring  48  are compressed together thereby retaining the rings  36  and  38  therebetween. The upper and lower neck rings  46  and  48  may be held together by snap fit as exemplified in  FIG. 13 , or may be retained in compressive relationship by threaded screws or through welding, heat application or other means. As shown in  FIG. 14 , upper neck ring  46  may contain a plurality of hooks  146  spaced along its perimeter. An equal number of aligned apertures  148  in lower neck ring  48 , as shown in  FIG. 15 , permit passage of grasping ridge  147  on the end of hooks  146  through the apertures  148 , as shown in FIG.  14 . Grasping ridge  147  lockingly engages the underside of lower neck ring  48  so as to snap fit bind upper and lower neck rings  46  and  48  together. A retaining ridge or bead on the underside of lower neck ring  48  where grasping ridge  147  contacts lower neck ring  48  may be provided to facilitate the snap fit bind.  FIG. 17  demonstrates how clip retention hub  149  may be formed onto the side of hook  146  in order to force grasping ridge  147  to more tightly and permanently engage lower neck ring  48 . Various other known methods may be utilized to retain the upper and lower neck rings  46  and  48  in compressive relationship, any one of which may be selected. 
   The upper and lower neck rings  46  and  48  as well as the hood ring  15  may be made of a hardened plastic material such that they may be injection molded. It is therefor desirable that they may be made of a hardened plastic material so as to firmly hold the retaining ring  36  and sealing ring  38  in place and provide a rigid contacting surface for the rings and for the neck seal  20  to engage. It is further desirable that the hood ring  15  be able to readily slide over the exterior periphery of the two-piece neck ring  40  wherein the seal ring  38  extends slightly outward therefrom. 
   As shown in  FIG. 6 , the hood ring  15  has a working surface  17 . The hood ring working surface  17  of the present invention is the interior surface of the hood ring  15  which engages the seal ring  38  of two-piece neck ring  40 . The working surface  17  may extend from the top rim portion  16  of hood ring  15  and downward therefrom. The hood ring working surface  17  is that portion of the hood ring which engages the seal ring  38  of the two-piece neck ring  40 . It is preferable, as is shown in  FIG. 6 , that the hood ring working surface  17  of hood ring  15  not have any portion of the hood  12  affixed thereto. Thus, as is shown in  FIG. 6 , the hood  12  is sealingly affixed to the exterior wall of the hood ring  15 . The hood  12  as is shown in  FIG. 6  does not cover any portion of the hood ring working surface  17 . The hood ring working surface  17  thus is free to engage the seal ring  38  to provide a firm and air tight seal between two-piece neck ring  40  and the hood ring  15 . Multiple variations are therefor available for affixation of the hood  12  to the hood ring  15 . The hood  12  may be attached to the exterior surface of the hood ring  15  as is shown in  FIG. 6  or it may affixed to a portion of the top rim  16  of ring  15 . The hood  12  may therefor extend downwardly to the interior portion of the top rim  16  and adhesively affixed to the underside of top rim  16  or it may extend downward along the exterior portion of the ring  15  as is depicted. Of import, however is that the hood ring  15  have a hood ring working surface which is not encumbered by the hood  12  of the head tent  10  of the present invention. 
   The hood  12  of the present invention may be made of a clear plastic material which is gas impermeable. The hood  12  is preferably made of a transparent plastic so that the user may see through the hood  12 . The hood  12  may be manufactured of a material that is self-supportive of its structure, or other additional means may be utilized. In  FIG. 18 , the hood  12  has a structural cage  125  attached to it that supports the form of the hood  12  and prevents it from collapsing onto the patient&#39;s head and face. The structural cage may be stiff bands of plastic  126  or related material positioned in vertical rows around the surface of the hood  12 , or it may be a combination of vertical and horizontal bands. Alternatively, the structural support may be ribs of air pockets spaced around the hood  12 . These ribs when inflated with air provide structural support to the hood  12 . The support structure, in whatever form, provides rigidity to the hood  12  and assists in maintaining the proper shape of the hood  12  while in use. The support structure will prevent ballooning of the hood  12  when the hood is subjected to positive pressure as well as preventing the hood from collapsing under its own weight when used in a neutral pressure environment. 
   The interior volume of the hood  12  can vary according to need and still fall within the scope of the present invention. The interior volume of the hood  12  may vary depending on the therapeutic needs. Patient preference and comfort are also factors affecting the choice of hood volume. For example, a smaller hood volume may be desirable for therapies requiring positive pressure in the hood because the required pressure can be reached more quickly with a smaller volume hood  12 . Smaller hood volumes may require an increase in airflow through the hood since carbon dioxide will increase at a more rapid rate than the larger hood volumes due to respiration by the patient. Hood volume may be varied either by increasing or decreasing the diameter of the hood ring  15  and two-piece neck ring  40  or by extending the sides of the hood  12  outward or upward. In one embodiment, the hood ring has a diameter of between about ten to twelve inches. 
   As shown in  FIG. 2 , the hood  12  is affixed to the exterior portion of hood ring  15  and may be attached thereto through the use of adhesives or welding. The means of attachment of the hood  12  to the hood ring  15  may be utilized when the hood is affixed to the exterior surface of the hood ring  15  or to the underside of top rim  16  so long as the lower periphery of the hood  12  is not located on the hood ring working surface  17 . 
   The two-piece neck ring  40 , shown in  FIG. 4 , is comprised of the upper neck ring  46  and lower neck ring  48 . As indicated, the first gas port  41  is cylindrical in design and extends upwardly and downwardly from the upper neck ring  46 . As shown in  FIG. 5 , a portion of the upper neck ring  46  is indicated with the first gas port  41  clearly depicted therein. Also shown in the closeup is the device port  43  which allows monitoring devices to be extended through the upper and lower neck rings  46  and  48  into the interior of hood  12 . As shown in  FIG. 5 , first gas port  41  extends upwardly and downwardly from upper neck ring  46  such that the lower extension extends through the first access aperture  31  of the lower neck ring  48  shown in FIG.  3 . Thus, the lower extension of the first and second gas ports  41  and  42  are readily accessible underneath the lower neck ring  48  and may be connected to an air supply and air removal system. 
   Turning to the alternative embodiment of the present invention shown in  FIG. 7 , the hood ring  115  may have a small annular groove  117  for receiving a locking clip  120 . Locking clip  120  may be utilized to retain the hood ring  115  attached to the two piece neck ring  40 . As is shown in  FIG. 7 , the locking clip  120  has an upper clasp  121  which extends downward and into groove  117 . Clasp  121  retains the clip  120  in place. Locking clip  120  may be utilized to keep the ring  115  firmly affixed to the neck ring  40  when an increased pressure is used inside hood  12 . By increasing the pressure within the hood  12 , downward force will be visited upon the neck ring  40  as the neck ring  40  and hood ring  115  attempt to separate. Locking clip  120 , having upwardly extending retaining edge portion  123 , prevents the downward movement of the neck ring  40  from occurring. 
   Hood ring  115  can also be modified to include recess  118  for receiving the locking clip  120  in the unlocked position as is shown in FIG.  8 . The neck ring  40  may then move freely downward away from the top inwardly directed edge  116  retaining the neck ring  40  in place. Clip  120  may have grasping tongue  122  for pulling the retaining edge portion  123  away from the inner surface of the hood ring  115 . Thus,  FIG. 7  depicts the locking clip  120  in a fully locked position with the retaining edge portion  123  extending upwardly directly below the neck ring  40 , not shown in FIG.  7 . In  FIG. 8 , the locking clip  120  is moved into the unlocked position, allowing retaining edge  123  to be placed in the recess  118  so that the neck ring  40  can be separated from the hood ring  115 . 
   Another preferred embodiment of the present invention is shown in  FIGS. 9-12  wherein the gas hood of the present invention is particularly useful for respiratory therapies which include, but are not limited to, for example, continuous positive airway pressure (CPAP), oxygen therapy, reanimation, intensive care, pneumatology and non-invasive positive ventilation. The gas hood may be used with not only oxygen therapy, but also with a mixture of other gases, including but not limited to nitrogen, carbon dioxide, and helium. For example, CPAP therapy with a mixture of helium and oxygen (heliox) may be useful as a treatment for chronic obstructive pulmonary disease and acute asthma. It has been proposed that since heliox is less dense than air and oxygen, using it may improve gas flow through partially obstructed airways. Therefore, utilized in conjunction with the gas hood of the present invention, heliox may be helpful in the treatment of diseases where the airway is partially obstructed. If CPAP therapy is used with a hood of the present invention, then a means of controlling the exhaust rate of gases is incorporated into the hood. The controlling means may be a limited diameter cap fixed over an exit port such as second gas port  42 . Another example of a means of controlling the exhaust rate of gases during CPAP therapy can be a variable dial-up valve mounted on an exit port to permit a adjustment of gas outflow. 
   As shown, a hood ring  215  ( FIG. 10 ) slides over the upper neck ring  46  and lower neck ring  48 , as shown in FIG.  12 . The hood ring  215  is similar to the hood ring  15 , but includes an inwardly directing edge  216  which includes a circumscribing groove  287  therein, groove  287  receiving a groove engaging tip  276  of a locking clip  275 . Moreover, the hood ring  215  includes a cut out  286  for receiving a lower ring engaging tip  277  of the locking clip  275  thereunder. The hood ing  215  also includes a pair of strap holding tabs  285 , as shown on the front of the hood ring  215 , and corresponding tabs on the back side of the hood ring  215  (not shown). Strap tabs  285  receive shoulder traps  290  as shown in phantom lines in FIG.  9 . The shoulder straps  290  being attached to the hood ring  215  fit a patients underarm to prevent the hood  210  from disengaging from the shoulders of a patient  200  when pressure is received within the hood  210 . For example, during CPAP therapy, the pressure inside the hood will be greater than ambient air outside the hood and tabs  285  in conjunction with straps  290  will keep the hood  210  securely on the patient. In contrast, during oxygen therapy, the air pressure inside the hood  210  remains in equilibrium with ambient air pressure and therefore, it may not be necessary to utilize tabs  275  and straps  290 . An alternative strap holding tab  385  is shown in FIG.  16 . 
     FIG. 12  shows an assembly of the gas hood  210  using the locking clip  275  to prevent the separation of the upper and lower neck rings  46  and  48 , respectively, when a patient is receiving pressurized gas. The upper and lower neck rings  46  and  48 , are assembled in the same manner as discussed previously and as shown in FIG.  4 . However, in  FIG. 12 , the hood ring  215  receives on its underside of the inwardly directing edge  216 , the terminating end  213  of the transparent hood  212 . The terminating end  213  may be adhesively secured to the underside of the edge  216  or secured by welding or any other well known means for attachment. The terminating end  213  is disposed between the edge  216  and the upper neck ring  46 . The neck seal  220  is sealingly engaged between the upper and lower neck ring  46  and  48  as the neck seal periphery  222  is inserted into the interior portion and retained in place by retaining ring  36  in cooperating relation with retaining ridge  45  of lower neck ring  48 . Additional sealing ring  38  is provided on the exterior periphery between the upper neck ring  46  and the lower neck ring  48  at the upper neck ring edge  49  and the lower neck ring edge  44 . The lower engaging tip  277  of the locking clip  275  is inserted through cut out  286  and engages with the edge  44  and the groove engaging tip  276  is engagable within the groove  287  wherein the engaging tips  276  and  277  prevent the separation of the hood ring  215  and the upper and lower neck rings  46  and  48 , respectively, when in use. Grasping tongue  278  is provided for pulling the lower engaging tip  277  from engagement with the lower neck ring  48 . Usually, there are a plurality of locking clips  277  spaced around the hood ring  215  and preferably 4 to 6 of these clips are utilized to keep the three rings  215 ,  46 , and  48  from separating when the gas hood  210  is in use. 
   As shown in  FIG. 9  in the use of the gas hood  210  for respiratory ailments, the gas hood  210  is placed over the head  200  of a user. The neck seal  220  is made of a flexible elastomeric material and has an opening  211  cut therein, opening  211  being cut to sealingly engage with the neck of the user  220 . The treatment hood  210  is then sealed around the user&#39;s neck and a pressurized gas, such as oxygen from a pressurized supply source, enters the hood through port  41 . Port  42  is left open allowing exhaust of gases, particularly carbon dioxide, expelled by the user from the interior of the hood  210 . The amount of gas pressure within the hood may be increased, decreased or kept the same as the external air pressure by varying the flow rate of gas into the hood from the pressurized supply source in combination with controlling the flow rate of gas exhaust from the hood. 
   While certain specific relationships materials and other parameters have been detailed in the above description of the preferred embodiments, these descriptions and structures may be varied where suitable with similar results. For example, as shown in  FIG. 17 , hook stand-off ridges  248  may be formed as appendages on the bottom of lower neck ring  48  and projecting downward toward the patient&#39;s shoulders. The ridges, which run parallel to each other and may circumscribe up to the entire lower neck ring  48 , function to prevent hooks  146  from contacting the patient. Such contact, if permitted, might snag clothing or cause discomfort to the patient when wearing the apparatus. 
   Other application variations and modifications of the disclosed head enclosing treatment hood will occur to those skilled in the art upon reading the present disclosure. Such modifications, while potentially being different in structure, are intended to be included within the scope of this invention as defined in the amended claims.