US 3428973 A
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'Feb. 25, 1969 FLUIDIZED T.. S. HARGEST E AL SUPPORTING APPARATUS Sheet of 2 I I0 q j b 9 7 n. 5 a v I I 7 6 .11 I I I I I I I I I I J! H l 2 INVENTORS THOMAS 3.,HAR6E'5'T CURTIS P. ARTZ CHARLES D. THOMPSON TRUMAN 6. BLOC/(ER, JR.
Feb. 25, 1969 T, 5, HARGEST ET AL 3,428,973
FLUIIDIZED SUPPORTING APPARATUS Sheet Filed March 17, 1966 INVENTORS FIG. 3
w WM 5 8 6 P n R m AZWC H770 R L 5 M 5 s L A THR w M rwcm United States Patent 3,428,973 FLUIDIZED SUPPORTING APPARATUS Thomas S. Hargest, 1078 Winslow Drive 29407, and
Curtis P. Artz, 13 Church St. 29401, both of Charleston, S.C.; and Charles D. Thompson, Austin, and Truman G. Blocker, Jr., Galveston, Tex.; said Thompson and said Blocker, assignors to said Hargest and said Artz Filed Mar. 17, 1966, Ser. No. 535,129 US. Cl. 5347 23 Claims Int. Cl. A47c 27/00 ABSTRACT OF THE DISCLOSURE Apparatus for and method of supporting and treating a hospital patient by a fluidized bed which includes a tank portion which is partially filled with a mass of granular material which is covered by a gas permeable flexible supporting member upon which the patient is disposed while the granular material is fluidized by the passage of air upwardly through the granular mass at a rate which will fluidize the granular mass to reduce the specific gravity thereof to a predetermined value best suited to float the patient disposed on the supporting member. The gas permeable supporting member permits the gas to pass around and in contact with the body of the patient and the temperature, humidity and character of the gas may be controlled as best suits the needs of the patient.
Summary of invention This invention relates to a hospital bed particularly adapted for use by patients inflicted with severe burns or other injuries where it is painful or not conducive to recovery to lie on an ordinary bed.
When a conventional mattress is used, the full weight of the patient is unevenly distributed over the areas of the patients body contacting the mattress causing relatively high pressure areas on portions of the patients body. In liquid-filled mattresses, such as that shown in US. Patent No. 3,108,293, a cover must be used to keep the patient out of contact with the liquid. This cover acts as a hammock and itself distributes pressure unevenly over the patients body which the buoyant force of the liquid is unable to overcome. In addition, both conventional and liquid-filled mattresses prevent air from circulating freely over areas of the patients body resting on the mattress. A liquid-filled mattress also presents a problem of heating the patient. Although the liquid can be heated and thus the patient, this requires a great deal of time and heat and is not easily regulated.
It is therefore a principal object of this invention to provide a fluidized bed which allows the weight of a patient to be evenly distributed on the supporting surface of the bed.
It is another object of this invention to minimize concentration of pressure on any localized parts of the body of a patient due to his own weight by means of a fluidized bed.
It is a further object of this invention to provide a bed which forms a natural contour bed from particulate material which has been fluidized.
It is a still further object of this invention to provide a fluidized hospital bed which provides circulation of air and other gases around the patient while resting in the bed.
It is yet another object of this invention to provide a fluidized hospital bed including provisions for the control of the temperature and humidity of gas circulating around the patient.
It is also an object of this invention to provide a "ice method of supporting a patient by means of a gas-fluidized particulate material and, as well, a method of treating the patient by controlling the composition and charac teristics of the gas fluidizing the medium to that prescribed for a given patient.
These and other objects are carried out generally speaking by providing a container partially filled with a granular material. The granular material is supported in the container on a diffuser which allows gas to pass upwardly through it and into the granular material. The container is covered by a sheet of porous material which allows gas to pass through it while preventing the granular material from also passing through it.
Means is provided for blowing a gas upwardly through the granular material causing it to be fluidized and act as a liquid. The patient will float on the bed as though he is floating on a dense liquid. The gas passes through the porous covering sheet and aerates the patient which is important in the healing of burned areas of the body. If the blowing gas is shut off, the granular material will gradually settle and conform to the shape of the patient thus forming a natural contour bed.
Further, the temperature, humidity and character of the gas passing around the patient may be regulated before its entry into the fluidized bed as best suits the need of the patient.
These and other objects will become apparent from the description which is in no way intended to limit the scope of the invention.
Description: of drawings In the drawings:
FIG. 1 is a perspective view of a bed constructed in accordance with this invention and showing a patient floating on the bed;
FIG. 2 is a vertical cross-section of FIG. 1; and
FIG. 3 is an exploded perspective view of the bed of this invention.
Referring to the drawings, 1 designates an open-topped tank, receiver or container which is preferably made out of some material which can be, easily cleaned and sterilized and sufliciently strong to support the components of the bed. It must also be fluid tight. Some possible materials are fiber glass, steel and epoxy-coated wood.
An expanded metal grate 5 having legs 6 fits into the tank 1 and rests on the bottom of the tank. A porous sheet material 3 fits into the tank and lays on top of the grate 5. This acts as a diffuser and is sufliciently porous to allow the passage of gas and sufriciently nonporous to prevent the passage of a fine granular material. This sheet material 3 should be of such a nature that when a gas passes through it, there is a low pressure drop across it. An air chamber or plenum 4 is formed between the sheet and the bottom of the tank. Above the diffuser 3, the tank is partially filled with a granular material 9 as best shown in FIG. 2.
A flexible sheet of material 10 is placed over the top of the tank and allowed to settle onto the granular material as best shown in FIGS. 1 and 2. This sheet 10 should be loosely fastened to the tank so that as it is raised and lowered, it will not become tight or be under tension. Any suitable fastening means (not shown) may be used. This pliable sheet material is sufliciently porous to allow the passage of gas and sufficiently non-porous to prevent the passage of granular material. An ordinary bed sheet may be used but the material used as dressing for burned areas of the body may be preferred.
A gas inlet 11 is placed in the tank 1 between the bottom of the tank and the grate 5 so that gas will enter the chamber 4. A hose 12 connects a compressor (not shown) with the gas inlet and supplies gas under pressure to the chamber 4. The gas then passes through the sheet 3 which acts as a diffuser to prevent jets of air from reaching the granular material. By using a diffuser 3, the gas delivered from the compressor will be evenly distributed throughout the granular material.
In operation, the gas flows into the chamber 4 from the compressor, through the diifuser 3, fluidizes the granular material and then passes upwardly through porous sheet 10. When the gas flows through the granular material 9, it is suspended or floats in the air and thus is fluidized. This phenomenon is widely used in chemical processes in the use of catalysts as shown in U.S. Patent No. 2,625,442. However, unike chemical processes, the amount of gas passed through the granular material in this invention should not be such as to reach the dispersion stage. That is, the granular material should float in the gas which is passed through it, not be exhausted out the top of the container 1. Therefore, the proper air flow should be determined from the size of the bed, the size of the granular material and the size of the patient to be supported as well as other factors which will become apparent.
The patient lies in the bed and air or other gas is sup plied so that the granular material is fluidized. When fluidized, the granular material acts as a liquid and the patient will float. Due to the buoyant force provided by this liquid-like medium, the weight of the patient is evenly distributed over all parts of his body. There is less pressure on the injured area, and recovery is hastened.
The greater the specific gravity of the liquid, the greater the buoyant force and the better a person or other object will float. Since not all people are able to float with ease in water, having a specific gravity of one (1), the fluidized material should have a specific gravity greater than one (1). The granular material should, therefore, be fluidized until its specific gravity is somewhere between that of water, one (1), and the granular material when it is not fluidized. The specific gravity of the fluidized material is dependent on the amount of granular material and the amount of air or gas.
The choice of a granular material is wide. Possible materials include sand, plastic beads and glass beads. Fluidization works best if a regular shaped material is used and a spherical shape seems to work best. A material should be used that will retain its shape; it should be inert so that when air or other gas is passed through it, the patients health will not be endangered. The material should be capable of being sterilized. The weight of the material becomes important in determining the final specific gravity of the fluidized granular material, the pressure drop across it and thus the amount of air flow required to fluidize it, and the strength of the container necessary to hold the material. The needs of the patient are also important when choosing a material.
For certain requirements, glass beads seem to work best. The size of these beads should be uniform in any one application. Glass beads in the range of .002 to .050 inch have been successfully used in the hospital bed.
In a child-size bed measuring 5 feet by 2.5 feet, glass beads measuring .0041 inch to a depth of 8 inches were used. About 40 c.f.m. of air at 25 psi. was used to fluidize the bed. A different granular material, different size bed, different patient or application will require dilferent amounts of air at different pressures.
In order to maintain sterility, the granular material must be periodically cleaned. This may be done by two methods. A screen 7, shown in FIG. 3, may be passed through the granular material when it is in a fluidized state by lifting on handles 8. This method is useful for picking up any large objects which may have fallen into the granular material and for separating beads which have stuck together.
The other method of cleaning is to remove the granular material and sterilize it. One methodfor removing the material is sucking it out by use of a vacuum cleaner or the like. Another method is to have a port 2 in the side of the container 1 between the diffuser 3 and the porous sheet 10. When it is desired to remove the granular material, it is fluidized and the port 2 is opened. The granular material will then flow out of the port like any liquid. Other methods of cleaning may be better suited for different materials or applications.
For the treatment of burned patients, it may be desirable to use different types of gases to fluidize the bed. It is a recognized treatment of burned and other patients to surround the injured area with air, nitrogen or carbon dioxide enriched air. Other gases may be desirable for treatment. With this invention, uniform aeration of the patient may be achieved. Treatment becomes very flexible. Attached to the compressor (not shown) there may be supplies of pure gases for treatment. Temperature and humidity controls should also be attached to the compressor as well as means for sterilizing the air or other gas. Since a patient will have to sleep in the bed, temperature and humidity must be controllable to keep the patient comfortable as well as control treatment. It may be desirable to provide a temperature control 13 within the chamber 4. Although the temperature control may be located at the compressor, heat loss between the compressor and the chamber is eliminated by locating the temperature control in the air chamber 4.
The compressor should also be equipped with slow opening valves to prevent rupture of the sheet material and air regulators to prevent pressure surges in the bed.
Although this invention is particularly applicable to burned patients, it may be used for control of infections by using various gases, hypothermia and humidity control. The bed may be used in orthopedic applications for fixation and traction. The bed can be used to support patients in a prone position when it is not advisable in a. standard bed.
From the above description, it can be seen that the hospital bed of this invention has many uses in the treatmetnt of patients which would otherwise require many pieces of equipment. The bed of this invention can also be used in non-medical areas. The considerations of weightlessness in space can be tested by using this bed since the patient becomes essentially weightless when the bed is fluidized. There are also many cases in industry when it is desired to float an object but not in a liquid.
Having described a preferred embodiment, what we claim is:
1. A bed for supporting a person comprising:
an open container;
a mass of granular material disposed within said container;
means for supporting said granular material in said container;
means for passing a gas through said granular material at a rate suflicient to fluidize said granular material, and
means including a gas permeable and pliable material enclosing said open container above said granular material for preventing said granular material from leaving said container and providing the upper surface of the bed upon which a person may be floated on said fluidized granular material.
2. The bed of claim 1 wherein said means for supporting the granular material comprises a dilfuser which is sufliciently porous to allow the passage of gas and sufliciently non-porous to prevent the passage of the granular material.
3. The bed of claim 1 wherein a plenum chamber is for-med between the bottom of the container and the supporting means and further including means for connecting said means for blowing a gas through said granular material to said plenum chamber.
4. The bed of claim 3 wherein said means for blowing a gas through said granular material comprises a compressor; said compressor having means for controlling the humidity of said gas and means for controlling the type of gas; said plenum chamber having means for controlling the temperature of said gas.
5. The bed of claim 1 wherein said granular material is uniform in size, shape and Weight.
6. The bed of claim 5 wherein said granular material is spherical glass beads.
7. The bed of claim 1 further including screen means for cleaning said granular material.
8. The bed of claim 1 further including port means in the side of said container for removing said granular material.
9. A device for supporting an object comprising:
a container having an open upper end;
a mass of granular material disposed within said container;
a pliable sheet of material covering said open end of said container and lying in contact with said granular material, and
means for blowing gas through said granular material to fiuidize said granular material without forcing said granular material out of said container whereby an object placed on said sheet of material will be supported thereon by said fluidized material.
10. A non-wetting fluidized supporting medium providing uniform reaction against an article supported thereon comprising:
a granular mass of material;
means pliable at least in the area of the article to be supported enclosing said granular mass and permeable to air but impermeable to said granular mass for restricting said granular mass within predetermined bounds, and
means for injecting a flow of gas through said granular mass of suflicient volume to fiuidize said mass and reduce the specific gravity thereof to a value best suited to provide conforming support for any given object disposed on said means enclosing said granular mass.
11. Apparatus for uniformly supporting an object placed thereon comprising:
a gas impermeable base portion,
a supporting cover affixed to said base portion and closing said base portion to define an enclosure,
a mass of granular material disposed within said enclosure, and
means for injecting a flow of gas through said mass of granular material of sufiicient volume to fiuidize said mass and reduce the specific gravity thereof to a value determined by that necessary to support a given object on said supporting cover.
12. A therapeutic apparatus for supporting and treating a convalescing patient comprising:
a base portion defining an upright tank,
a mass of granular material disposed within and partially filling said tank,
a soft pliable and gas permeable supporting member enclosing the upper portion of said tank and lying in engagement with said granular mass, and
means for injecting a flow of gas through said granular mass of volume sufficient to cause fiuidization of said mass to reduce the specific gravity thereof to a predetermined value best suited to float a given patient disposed on said supporting member.
13. The therapeutic apparatus of claim 12 further including means for controlling the temperature of said flow of gas injected into said granular mass to that needed by the patient.
14. The therapeutic apparatus of claim 12 further including means for controlling the humidity of the gas injected into said granular mass.
15. The therapeutic apparatus of claim 12 further including means for controlling the character of said gas injected into said granular mass to provide a healing and medicinal medium of gas passing about the body of the patient.
16. A therapeutic bed for uniformly supporting a .person comprising:
a granular mass of material capable of fiuidization under the influence of a gas circulated therethrough,
means for flowing a gas through said granular mass at a rate suflicient to fiuidize said mass to a degree at which the specific gravity thereof reduces to a value slightly greater than that of the person, and
a receiver for said granular mass for maintaining said granular mass within said predetermined bounds during fiuidization thereof including at least a pliable upper member on which the person to be treated is placed which is capable of generally conforming to the configuration of the person thereon.
17. The method of therapeutically supporting and treating a convalescent patient comprising:
enclosing a mass of granular material within a receiver,
the upper portion of which is formed of a soft pliable and gas permeable material capable of conforming to the contour of the patient, and
fluidizing the granular mass by injection of gas therethrough to reduce the specific gravity of the granular mass to a value greater than that of the patient but low enough to uniformly support the patient.
18. The method of claim 17 further including the step of controlling the temperature of the gas fluidizing s-aid granular material and passing around the body of the patient to the temperature best suited for the needs of the patient.
19. The method of claim 17 further including the step of controlling the humidity of the gas fluidizing said granular mass and passing about the body of the patient to that best suited to the needs of the patient.
20. The method of claim 17 further including the step of controlling the character of the gas utilized for fluidizing the medium and passing around the body of the patient so as to provide a healing medium.
21. A hospital bed for supporting a patient comprismg:
an open-top fluid-tight container having substantial depth and a length and breadth substantially corresponding with those of a conventional bed;
porous wall structure spaced above the bottom of the tank and forming a diffuser throughout substantially the length .and breadth of the container, the space between said porous wall and the bottom of said container forming a plenum chamber;
a mass of granular material, the particles of which are of substantially uniform shape partially filling that part of the container above said porous wall structure;
a pliable sheet attached at its peripheral portion to the upper portion of said container having a width and length to permit said sheet to lie loosely on the top of said mass of granular material;
said porous wall structure and said pliable sheet being impermeable to said granular material but permeable to gaseous material; and
means for supplying gaseous material under pressure to said plenum chamber for flow upwardly through said difluser and granular mass of sufficient volume to fiuidize said granular mass and reduce its specific gravity to take on the properties of a liquid to float a patient upon said pliable sheet and fiuidize granular material thus supporting the patient evenly over all parts of his body in avoidance of concentrated pressure on restricted areas thereof.
22. The hospital bed of claim 21 in which said pliable sheet is sufliciently loose fitting within said container that upon failure of said source of gaseous materials under pressure, the bed will lose its fluidity with the patients body supported on a partial enveloping body of said granular material.
23. The hospital bed of claim 21 in which said granular material has particle sizes in the range of from .002 inch to .050 inch.
(References on following page) References Cited UNITED STATES PATENTS Crondal 5-361 Maddison 5-347 Hogin 34-57 King 5-348 Gates et a1. 34-57 Munro et a1 34-57 8 FOREIGN PATENTS 7/1963 Great Britain.
BOBBY R. GAY, Primary Examiner.
US. Cl. X.R.