Abstract:
A portable, collapsible hyperbaric chamber. A toroidal inflatable skeleton provides initial structural support for the chamber, allowing the attendant and/or patient to enter the chamber. Oval hatches mate against bulkhead rings, and the hyperbaric chamber is pressurized. The hatches seal against an o-ring, and the internal pressure of the chamber provides the required pressure against the hatch to maintain an airtight seal. In the preferred embodiment, the hyperbaric chamber has an airlock to allow the attendant to enter and exit the patient chamber during treatment. Visual communication is provided through portholes in the patient and/or airlock chamber. Life monitoring and support systems are in communication with the interior of the hyperbaric chamber and/or airlock chamber through conduits and/or sealed feed-through connectors into the hyperbaric chamber.

Description:
ORIGIN OF THE INVENTION 
     The invention described herein was made by employees of the United States Government and may be manufactured and used by or for the government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to a hyperbaric chamber. Specifically, the invention describes a human hyperbaric chamber and airlock system that is lightweight, portable, stowable and collapsible. It provides the atmospheric pressures (over two atmospheres) required for standard hyperbaric medical treatments, including both hypobaric and hyperbaric decompression sickness. The device can be sized to contain at least one patient and attending medic(s). 
     2. Background Information and Related Art 
     Humans can experience altered atmospheric pressures in several environments (aviation, submarine operations, spacecraft, extravehicular space activities, scuba diving, etc.) Decompression sickness can develop under these conditions, occasionally leading to serious or fatal injury. Hyperbaric chambers are successfully used to treat decompression sickness. 
     Conventional hyperbaric chambers, made of solid metal, are heavy, have permanently high volume, and are not readily portable. For remote operational environments (International Space Station; civilian, commercial and military diving operations), conventional hyperbaric treatment chambers are often unavailable because of their lack of portability. A lightweight, portable, collapsible chamber would provide much-needed decompression sickness treatment capability in remote areas without great weight or stowage penalties. Currently, portable chamber designs exist, but often can not provide maximum standard therapy due to structural and pressure limitations. Their lack of an integral airlock prohibits access to the pressurized patient, thereby markedly decreasing the level of safety and treatment flexibility. Current portable chambers either have a permanent rigid skeleton (which dramatically increases storage volume), or lack internal support (which makes access extremely difficult and unpleasant when the chamber is not pressurized.) Many currently available collapsible chambers are sized for only one occupant (the patient), which limits the ability to treat and care for the patient. 
     Prior art for flexible hyperbaric chambers includes that described by Santi in U.S. Pat. No. 5,738,093. The present invention differs from the Santi patent in several important respects. First, in Santi the hatch is closed by rotating the hatch engaging threaded sectors. When pressurized, this places a heavy pressure load on the hatch threads, requiring the hatch and supporting structures to be very heavy. Second, the longitudinal and hoop straps supporting the chamber bladder are designed to have large spaces between the straps, requiring the chamber bladder to have a high strength and thickness in order to prevent billowing through the web spaces. Third, the straps are terminated at each end by looping the strap through a slot in a thin metallic fitting and stitching the strap onto itself. The thin metallic fittings are then bolted to the end rings. The slot in the thin metallic fitting forces the webbing to bend in a sharp radius that a) causes a high local stress in the straps, creating potential failure points and reducing the safety margins and b) creates high friction at the interface of the webbing and the thin metallic fitting, causing uneven load sharing between the outside of the loop and the inside of the loop. Fourth, the feed-through provisions for air, instrumentation wiring, pressurization etc. are located in the hatch itself, creating very cumbersome hatch operations due to the restrictive nature of the attached lines to the hatch. 
     Other examples of inflatable chambers include patents by Cardwell as disclosed in U.S. Pat. No. 5,255,673 and Bleiken in U.S. Pat. No. 3,602,221. Both devices lack any type of internal structural support before they are sealed and pressurized. Thus, when the patient is first placed in the collapsed device, part of the device is lying on top of him. These conditions make positioning the patient and equipment inside the device very difficult, poses a possible suffocation exposure, and can induce dangerous anxiety in claustrophobic individuals. Further, these and other typical prior art inflatable chambers are designed for only one occupant, making the presence of a medical attendant impossible. 
     The sealing systems for prior art inflatable chambers have various limitations. Some, such as disclosed by Miller in U.S. Pat. No. 3,729,002, use a zipper and seal system which is zipped and then reinforced by a loop and rod system inserted externally. Such a system creates high local stresses in the flexible fabric, which must therefore be heavy and bulky. 
     It would thus be a new and useful improvement to a portable hyperbaric chamber to accomplish the above-described purposes without the limitations of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, the objectives of this invention are to provide, inter alia, a new and improved portable hyperbaric chamber that: 
     is lightweight; 
     is portable; 
     is collapsible and flexible; 
     can be stored flat with minimal volume; 
     provides maximum standard hyperbaric treatment conditions for one patient and an attending medic; 
     contains an integral airlock for access to the main chamber by personnel and/or equipment; 
     includes conduits that provide air, medical oxygen, electrical power and communication to both the airlock and chamber; 
     includes transparent viewports in both the airlock and chamber vessels; 
     includes hatches that are lightweight and easily engaged and disengaged; and 
     utilizes multilayer construction of flexible materials that provide an extremely sturdy pressure vessel. 
     These objectives are addressed by the structure and use of the inventive collapsible hyperbaric chamber. Due to the multilayer construction of flexible materials, the chamber collapses for flat storage with minimal volume, while maintaining a very sturdy pressure vessel capable of resisting punctures as well as internal pressures over four atmospheres. Equipment and personnel can be transferred into and out of the chamber via an integral inflatable airlock attached to the main inflatable chamber. The airlock chamber and main chambers are mated together by a main chamber hatch bulkhead. The main chamber hatch bulkhead includes passages for pressure lines, communication lines, medical oxygen and electrical power, each of which can be dedicated to either the airlock chamber or the main chamber. 
     The airlock chamber and main chamber each have an internal inflatable skeleton to maintain the chambers&#39; volumes during the non-pressurized mode for ease of access without appreciably decreasing the living volume. Both chambers are constructed of an internal bladder within a restraint layer. The restraint layer is composed of flexible retaining straps running circumferentially and longitudinally around each chamber in a loose but contiguous weave. The internal bladder is oversized to allow the retaining straps to contain the force loads of the internal pressures of the chambers. 
     Other objects of the invention will become apparent from time to time throughout the specification hereinafter disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts the inventive hyperbaric chamber and airlock. 
     FIG. 2 depicts the inflatable skeleton of the hyperbaric chamber. 
     FIG. 3 depicts the main chamber of the hyperbaric chamber in exploded view. 
     FIG. 4 depicts the cross weaving of the straps supporting the bladder of the main chamber. 
     FIG. 5 depicts details of the straps roller attachments and hatch/hatch ring mating. 
     FIGS. 6A-C depict the main interface ring. 
     FIG. 7 depicts the insertion of the hyperbaric chamber hatch through the main interface ring orifice. 
     FIG. 8 depicts the hyperbaric chamber hatch and main interface ring orifice in isometric view. 
     FIG. 9 depicts the airlock chamber of the hyperbaric chamber. 
     FIG. 10 depicts main interface ring when designed for an attaching airlock chamber. 
     FIG. 11 depicts detail on the preferred embodiment of the support strapping around the chambers. 
     FIGS. 12A-C depict the sequence of personnel entry into the hyperbaric chamber. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is described as hyperbaric chamber  10 . As shown in the preferred embodiment in FIG. 1, chamber  10  comprises an integral airlock chamber  20  and patient chamber  30 . Airlock chamber  20  is sealed from the outside by airlock hatch  65 , and patient chamber  30  is sealed by chamber hatch  55 , shown in FIG.  2 . External life support systems  40 , including pressurized air supply/revitalization, power supply, communications lines, etc., are linked to hyperbaric chamber  10 , for both airlock chamber  20  and patient chamber  30 , by sealed umbilicals  35  passing through main interface ring apertures  48  in main interface ring  50 , or by mating with sealed connectors (not shown) similarly located on interface ring  50 . 
     As seen in FIG. 2, airlock chamber  20  and patient chamber  30  each have airlock inflatable skeleton  170  and inflatable skeleton  70 , respectively, which provide initial skeletal support prior to the introduction of internal air chamber pressure, which then maintains the shape and structure of hyperbaric chamber  10  during use. Inflatable skeleton  70  and airlock inflatable skeletons  170  are preferably a plurality of contiguous toroidal tubes, or alternatively a continuous helical tube, that define interior spaces for patient chamber  30  and airlock chamber  20 . Inflatable skeleton  70  and airlock inflatable chamber  170  are preferably constructed of strong, flexible, air impermeable material such as rubber. 
     The overall construction of patient chamber  30  is shown in exploded view in FIG.  3 . The basic shape of patient chamber  30  is defined as a cylindrical ellipsoid by bladder  85 , inflatable skeleton  70  (FIG.  2 ), longitudinal straps  75  and circumferential straps  80 . The general shape is first defined by inflatable skeleton  70  (seen in FIG.  2 ), which is a plurality of contiguous toroidal tubes or a single helical tube secured to the interior of bladder  85 . As inflatable skeleton  70  inflates, the lateral and longitudinal internal pressures of inflatable skeleton  70  against the interior of bladder  85  cause bladder  85 , as well as longitudinal straps  75  and circumferential straps  80 , to expand to a general cylindrical toroidal shape. 
     While inflatable skeleton  70  is depicted as interior to bladder  85 , alternatively inflatable skeleton  70  can be an exoskeleton (not shown) attached to the exterior of bladder  85 , and performing the same function by pulling bladder  85  open instead of pushing it open as shown in the preferred depiction. 
     As shown in FIG. 3, patient chamber  30  comprises bladder  85 , which includes a bladder open end  87  and a bladder closed end  68 . Bladder open end  87  provides an aperture for patient  96  (FIG. 12) and attendant  97  (FIG. 12) to enter and exit patient chamber  30 . Bladder open end  87  has a bladder interior rim  86 , which is secured, typically by mechanical fasteners, to main interface ring  50  by bladder clamp  51 . 
     Surrounding bladder  85  are longitudinal straps  75  and circumferential straps  80 , both types of straps preferably being made of KEVLAR® or material with similar strength and flexibility characteristics. Circumferential straps  80  are preferably tightly cross-woven with longitudinal straps  80  as depicted in FIG.  4 . By tightly cross weaving circumferential straps  80  with longitudinal straps  75  to form a tight weave, the internal pressure from bladder  85  is restrained by the tightly woven straps, rather than bladder  85  itself. This allows bladder  85  to be of material that is lighter and thinner, since it does not have to provide support for the outward forces of the internal pressure on bladder  85 , thus allowing bladder  85  to be more flexible for storage. 
     Longitudinal straps  75  are secured to main interface ring  50  with roller assemblies  90  as depicted in FIG.  5 . Roller assembly  90  includes roller bracket  92 , which holds roller  91 . Roller bracket  92  is integral with, or is secured, typically with mechanical fasteners, to main interface ring  50 . Longitudinal straps  75  preferably terminate in a loop that wraps around roller  91 , thus minimizing edge strain against longitudinal strap  75 . In the preferred embodiment, strap  75  is a single unit as depicted in FIG.  11 . Each longitudinal strap  75  loops around a pair of rollers  91 , each in the pair being located on opposite sides of main interface ring  50 . Each longitudinal strap  75 , as shown in FIG. 11, comprises a double layer except where it loops around each roller (single layer) and interlapping area  76  (triple layers). Each longitudinal strap  75  is stitched only in interlapping area  76 , which comprises typically three overlapping layers of longitudinal strap  75 . For each longitudinal strap  75 , interlapping area  76  is located at a different distance  77  from roller  91 , such that interlapping area  76  of longitudinal straps  75  are not in the same plane for any plane transverse to longitudinal straps  95 . Thus the distance  77  between stitching area  76  and roller  91  is different, preferably at a uniform progression of distance, from any longitudinal strap  75  to the next longitudinal strap  75 . 
     To protect bladder  85  from being cut or damaged by being rubbed by longitudinal straps  75 , bladder buffer  49  is positioned intermediate bladder  85  and longitudinal straps  75 . Typically, bladder buffer  49  has the shape of a narrow spherical frustum, as depicted in FIG.  3 . Bladder buffer  49  is constructed of a flexible wear resistant material, such as reinforced rubber. 
     FIGS. 6A-C depict main interface ring  50 , which acts as a bulkhead to the entrance of patient chamber  30 . Main interface ring  50  includes a main interface ring outer rim  53 , typically circular in shape. Interior to main interface ring  50  is ring elliptical orifice  52 , having a minor axis and a major axis. Between main interface ring outer rim  53  and elliptical orifice  52  are conduits  57  (or alternatively sealed connectors, not shown), which provide passageways for sealed umbilicals  35  (or sealed connections for hoses, electrical connections and other system connectors) to the interiors of patient chamber  30  and airlock chamber  20 . 
     Patient chamber hatch  55  is matable to main interface ring  50  to provide an airtight seal. As seen in FIG. 5, this seal is accomplished when patient chamber hatch  55  presses against O-ring  63 , which is oriented in a channel in main interface ring  50 . This pressing is accomplished when patient chamber  30  is pressurized, causing patient chamber hatch  55  to be pushed outward from the interior of patient chamber  30  against main interface ring  50 . Prior to patient chamber  30  being pressurized, patient chamber hatch  55  is temporarily held in place on main interface ring  50  by a magnetic surface on patient chamber hatch  55  and/or main interface ring  50 . The matching mating surface (main interface ring  50  or chamber hatch  55 ) is either a ferrous metal or having another magnetic surface capable of forming a magnetic bond. Thus either both mating surfaces of patient chamber hatch  55  and main interface ring  50  are magnetic, or one of the mating surfaces is magnetic while the other is a ferrous metal capable of being magnetically attracted by the matching magnetic surface. 
     As seen in FIG. 7, main interface ring  50  includes a ring elliptical orifice  52  having a major axis and a minor axis. Patient chamber hatch  55  has a hatch rim ellipse having its own major axis and minor axis. The minor axis of patient chamber hatch  55  is smaller than the major axis of ring elliptical orifice  52 . Therefore, by rotating patient chamber hatch  55  by 90° in the X-axis and Z-axis, it is able to be passed through ring elliptical orifice  52 . Once through, patient chamber hatch  55  is rotated back so that its major and minor axes are aligned with the major and minor axes of ring elliptical orifice  52  for mating of patient chamber hatch  55  and main interface ring  50 . 
     Patient chamber hatch  55  can be constructed of rigid material such as plastic or metal, or in the preferred embodiment has a flexible patient chamber hatch face  54 . In the preferred embodiment, patient chamber hatch face  54  is constructed of a flexible but strong airtight material that is bonded or attached to hatch rim ellipse  61 , as seen in FIG.  8 . Optionally, an interior patient viewport  56  is constructed within patient chamber hatch face  54  to provide visual communication with the interior or patient chamber  30 . When constructed of flexible material, patient chamber hatch face  54  can be reinforced with interwoven or adjacent strapping to provide additional retention strength against the air pressure from the interior of patient chamber  30  when pressurized. 
     In the preferred embodiment, hyperbaric chamber  10  includes an airlock chamber  20  attached to patient chamber  30 . As seen in FIG. 9, the construction of airlock chamber  20  is analogous to that of patient chamber  30 . Airlock bladder  185  is surrounded by airlock longitudinal straps  175  and airlock circumferential straps  180 . Airlock bladder  185  has two open ends, airlock entrance open end  66  and airlock interface open end  187 . Airlock entrance open end  66  mates to airlock hatch ring  60  by being clamped between airlock bladder clamp  151   a  and airlock hatch ring  60 . Secured to airlock hatch ring  60  are a plurality of airlock roller assemblies  190   a , comprising airlock rollers  191   a  and airlock roller brackets  192   a . Airlock longitudinal straps  175  loop around airlock rollers  191   a  to minimize cutting tension as described above for longitudinal straps  75  of patient chamber  30 . Airlock longitudinal straps  175  are stitched and looped in an analogous manner as described above for longitudinal straps  75 . Airlock circumferential straps  180  tightly interweave between airlock longitudinal straps  175  to provide pressure support of airlock bladder  185 , in a manner analogous to that described above for bladder  85  of patient chamber  30 . 
     Airlock chamber  20  attaches to main interface ring  50  as depicted in FIG.  10 . Airlock bladder  185  is clamped to main interface ring  50  by airlock bladder clamp  151   b , which pushes against O-rings in the side of main interface ring  50  as depicted. To protect airlock bladder  185  from airlock roller bracket  192   b  and airlock longitudinal straps  175 , airlock bladder buffer  149  is positioned exterior airlock bladder  185  at the area of interface shown in FIG.  10 . 
     Airlock bladder  185  is clamped at airlock entrance open end  66  to airlock hatch ring  60 , as seen in FIG.  9 . Airlock bladder  185  is clamped to airlock hatch ring  60  with airlock bladder clamp  151   a  against O-rings in airlock hatch ring  60  in a manner analogous to that described above for the bladder attachments to main interface ring  50 . Protection is further provided by airlock bladder buffer  149   a  between airlock roller assemblies  190   a  and airlock longitudinal straps  175  in a manner similar to that described above at main interface ring  50 . 
     Airlock hatch  65  mates with airlock hatch ring  60  in the manner described above for mating patient chamber hatch  55  and main interface ring  50 . 
     OPERATION 
     In the preferred embodiment, hyperbaric chamber  10  is stowed in a storage area of a room, ship, spacecraft or other area where space is limited. When deflated, hyperbaric chamber  10  collapses into a relatively small shape. 
     To prepare hyperbaric chamber  10  for use, bladder  85  and airlock bladder  185  are loosely stretched out. Inflatable skeleton  70  and airlock inflatable skeleton  170  are pressurized and inflated using a standard air pump. As they inflate, they provide a general shape to patient chamber  30  and airlock chamber  20 . Attendant  97  is now able to assist patient  96  into patient chamber  30  by crawling through airlock hatch ring  60 , airlock chamber  20  and main interface ring  50 . Life function monitor leads are attached to patient  96 , said leads typically connected via hard wire to remote monitor equipment outside hyperbaric chamber  10 . Attendant  97  then positions airlock hatch  65  against airlock hatch ring  60 , which are aligned by magnets on the surface of airlock hatch  65  and/or airlock hatch ring  60 . Both patient chamber  30  and airlock chamber  20  are pressurized by an air pump of external life support systems  40 . When patient chamber  30  and airlock chamber  20  are pressurized above 1.0 atmospheres, airlock hatch  65  presses against O-ring  163 , creating an airtight seal. 
     When attendant  97  desires to leave hyperbaric chamber  10 , he aligns patient chamber hatch  55  with main interface ring  50 . The pressure in airlock chamber  20  is bled off, creating a pressure gradient between patient chamber  30  (positive pressure) and airlock chamber  20  (neutral pressure). This pressure gradient now forces patient chamber hatch  55  against main interface ring  50  and its O-ring  63 , creating an airtight seal inside patient chamber  30 . To exit airlock chamber  20 , attendant  97  removes airlock hatch  65 , rotates it 90° in the X-axis and Z-axis such that the minor axis of airlock hatch  65  is able to pass through the major axis of airlock hatch ring  60 . 
     Entry by attendant  97  is depicted in FIGS. 12A through 12C. In FIG. 12A, attendant  97  crawls into airlock chamber  20 , and pulls airlock hatch  65  in through airlock hatch ring  60  by aligning the minor and major axes of airlock hatch  65  and hatch ring  60 . In FIG. 12B, attendant  97  positions airlock hatch  65  against airlock hatch ring  60  aligned along their major and minor axes, such that they are mated by magnetic force. Airlock chamber  20  is pressurized until at the same pressure of patient chamber  30 . This forces airlock hatch to seal against airlock hatch ring  60  and its airlock O-ring  163 . Patient chamber hatch  55  is now no longer providing an airtight seal to patient chamber  30 , since there is no longer pressure against it from the interior of patient chamber  30 . As seen in FIG. 12C, attendant  97  is now able to break the magnetic seal between patient chamber hatch  55  and main interface ring  50 , and push patient chamber hatch  55  into patient chamber  30  to allow entry into patient chamber  30 . 
     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.