RU2076676C1 - Soft altitude chamber of hyperbaric oxygenation system - Google Patents

Abstract

FIELD: medical equipment. SUBSTANCE: soft altitude chamber has patient's seat connected with supporting construction and hermetical container with cellular net. Container is made from thin film and net is made from kapron cord or metal wire. Shape and form of cell is in compliance with predetermined mathematical expression. EFFECT: increased efficiency and enhanced reliability in operation. 3 cl, 6 dwg

Description

 This technical solution relates to objects of technology used in medical practice for the treatment and prevention of patients under conditions of increased absolute and partial pressure of the oxygen environment (hyperbaric oxygenation system).

 A number of hyperbaric oxygenation systems based on rigid pressure chambers exist and operate in medical centers in many countries of the world. As a rule, rigid pressure chambers are tanks made of metals. To monitor patients placed inside the pressure chambers, the latter are equipped with portholes. The surface area of the windows should be as large as possible to eliminate psychological discomfort for the patient (the effect of confined space). For supplying electric energy, drugs, control signals to the internal chamber of the pressure chamber, as well as for the formation of an oxygen environment of high pressure and controlling it, the pressure chamber is equipped with appropriate assignments.

 In addition, attempts to create similar systems using soft materials as a pressure chamber of a pressure chamber are known.

 So, the pressure chamber of the company "Dregger", Germany, is made in the form of a sealed opaque cylindrical bag, which is worn on a lying patient without touching it, and in the neck area is fixed with an annular hermetic junction with a power stand of the camera. The strength of the bag at elevated pressure is also ensured by using a multi-wire mesh, worn on top of the bag and taking on part of the load.

 The pressure chamber "Irtysh-2MT" (one of the options), developed at the Zvezda engineering plant of the Ministry of Aviation Industry (USSR) in 1989 under an agreement with the All-Union Scientific Exhibition Center of the USSR Academy of Medical Sciences, is made in the form of two rigid bottoms connected by a soft, sealed opaque cylindrical shell. The strength of the shell is ensured by two tapes running along its surface in spirals of the right and left direction.

 The pressure chamber shown in the materials of patent N 578825 (USA) is close in design to the pressure chamber of the company "Dregger".

 The technical solution used in the pressure chamber of the company "Dregger", adopted as a prototype.

 The design flaws of the Dregger pressure chamber are the difficulty of placing the patient in the internal cavity of the soft bag (the stretcher with the patient inside the bag is directly on the floor), the isolation of the patient in a closed small space of the opaque bag and the impossibility or difficulty of observation by the medical staff, as well as difficulty in rescuing the patient in case of emergency (fire, interruptions in life support systems); the design of the bag does not show the optimal solution from the point of view of the formation of the stress-strain state of the bag shell system (film) mesh.

Regarding the last remark, considering the stress-strain state of the film-mesh system, it can be said that the Dregger pressure chamber was designed without taking into account the rational distribution of the load in the material of the bag (film) and mesh. As shown below in the description of the proposed technical solution, the relationship between the geometric shape of the bag (film) shell, which its surface must take within the cell formed by the mesh, and the strength characteristics of the material from which the mesh should be made, can be expressed by the inequality
α $\genfrac{}{}{0ex}{}{\text{2}}{\text{o}}$ > f • σ _c / E _c
That is, the correctly created system design of the film-mesh system must take into account that, in a state not loaded by internal pressure, the film slightly sags in the mesh cell and forms a bubble in the loaded cell.

 As can be seen from the image of the pressure chamber of the company "Dregger", the shell of its bag is loaded with significantly greater forces than necessary (a weakly pronounced bubble) with a correctly implemented loading scheme of the bag shell and mesh.

 In addition, the shell of the bag with a rope mesh is designed so that it does not allow observation and surgical intervention and access to the patient in case of danger to his life.

 The proposed technical solution allows to eliminate these disadvantages of the prototype, for which the pressure chamber housing is made in the form of a supporting structure to which a beam with a place for patient placement organized on it is attached at a certain distance from the floor surface. A sealed container, made in the form of a soft chamber, nested inside a multi-wire mesh, is pushed onto the power console, isolating the patient's place from the surrounding space. The soft chamber is sealed at the junction with the supporting structure, for example, using an annular telescopic joint and a clamp.

 A soft chamber is made of a thin film material, for example, vitur (a material from the class of polyurethanes), selected according to its characteristics so that it can withstand only the pressure inside it and serve only as the interface between two media and is strengthened by an outside woven mesh made of a bundle (tape ) or wire (non-metals or metals).

 The soft chamber in pepper and longitudinal dimensions is slightly larger than the mesh for rational distribution of loads in the film-mesh system and corresponding reduction to its maximum permissible thickness.

 It is possible to use an opaque material as a soft chamber as a structural material, but this greatly enhances the discomfort for the patient and worsens the observation conditions by medical personnel or complicates the design when the required number of windows is introduced into it.

 From the point of view of improving the loading conditions of the soft chamber in the mesh cells, the latter are made in the form of a figure close to a circle. When the soft chamber is loaded with internal pressure, in this case, the same internal stresses appear in the film in any section, which allows reducing the film mass to the minimum possible.

 The specified conditions are satisfied by a cell made in the form of a hexagon or circle.

 In FIG. 1 presents a General view of the hyperbaric oxygenation system (GBS); in FIG. 2 general view of the GBS without a soft pressure chamber; in FIG. 3 is a general view of the sealed container of a pressurized soft chamber SGBO; in FIG. 4 basic designations characterizing the geometric shape of a soft chamber with a multicellular mesh in cross section; figure 5 option loading soft chamber internal pressure and the forces arising in the film; in FIG. 6 embodiment of a grid with cells in the form of a hexagon.

 In the supporting structure 1 (Fig. 1 and 2) on the power console arranged placement of the patient 2; a soft chamber with a multi-mesh net 3 is attached to the supporting structure around the patient’s location, connected to the supporting structure by a sealed joint 4. In the absence of internal pressure, the camera film rests on removable supporting arms 5. On the supporting structure 1 are installed GBS 6 devices and, as an option, oxygen cylinders 7.

 The entire system can be moved along the surface of the floor, for which it is mounted on wheel 8.

 In the initial state, the patient’s GBO is laid in place 2. After the necessary manipulations for the patient (installation of sensors, droppers, etc.), a soft chamber is pulled with a mesh 3 and connected to the supporting structure using an airtight joint 4.

 Observation of the patient and negotiations with him are carried out through the transparent surface of the soft chamber.

 Further work with the system does not differ from work with other systems.

The operation of a soft chamber with a multi-wire mesh under internal pressure can be represented in this way (see Fig. 4,5):
When pressure p is applied inside a film of radius R _o closed in the form of a cylindrical shell or, in general, R _{x, the} film is loaded, and, relying on the grid, transfers the load to it
q _c = p • r _x • sinα _x
at the same time, voltage arises in the grid
σ _c = q _c • R _x / F,
where F is the cross-sectional area of the wire harness.

The mesh is deformed by
W _c = σ _c • R _x / E _c ,
where E _{c is the} modulus of elasticity of the mesh material, which leads to an increase in the radius R _o by the value of W _x , i.e.

R _x R _o + W _c .

составит

Относительная длина пленки в поперечном сечении в недеформированном состоянии из геометрических соображений (без внутреннего давления р пленка в ячейках сетки "провисает") составит

,
а в деформированном состоянии:

или 1+(σ_c/E_c)•α_x/sinα_x = α_o/sinα_o
Решение последнего уравнения относительно приращения угла Δα после разложения sinα_x и sinα_o в ряд Фурье дает примерно значение величины приращения угла

.Hence the relative change in radius

will make

The relative length of the film in the cross section in the undeformed state from geometric considerations (without internal pressure p the film “sags” in the mesh cells) will be

,
but in a deformed state:

or 1+ (σ _c / E _c ) • α _x / sinα _x = α _o / sinα _o
The solution of the last equation regarding the increment of the angle Δα after expanding sinα _x and sinα _o in the Fourier series gives approximately the value of the increment of the angle

.

а усилие в пленке

Ясно, что усилие в пленке стремится к бесконечности при α_o - 3•σ_c/E_c•sinα_o, стремящемся к нулю.From geometric relationships, the value of the radius of the film section in the grid cell

and the effort in the film

It is clear that the force in the film tends to infinity as α _o - 3 • σ _c / E _c • sinα _o tending to zero.

therefore
α _o • sinα _o > 3 • σ _c / E _c
or α $\genfrac{}{}{0ex}{}{\text{2}}{\text{o}}$ > f • σ _c / E _c
That is, in a properly designed system design, the film mesh should be taken into account so that the film sags in the pressureless state and forms a bubble in the mesh cell with sufficiently large values of α _o, which corresponds to the solution f> 3.

Claims (3)

1. Soft hyperbaric oxygenation chamber containing a patient seat connected to the support structure, a sealed soft container with a multi-mesh mesh, isolating the patient's place from the surrounding space, characterized in that the container is made of an extremely thin film designed only to hold the gas environment inside the container, for example, from a material of class polyurethanes, the mesh is made of a flexible bundle or tape, for example, a nylon cord (tape) or a metal wire (tape), while lzhno be the condition

where α _{o the} angle of the half-sector formed by approximating the real surface of the film by a sphere in the mesh cell;
[σ _c ] permissible stresses of the mesh material;
E _{with the} modulus of elasticity of the mesh material;
f> 3 is the coupling coefficient of these parameters.  2. The pressure chamber according to claim 1, characterized in that the film of the container is made transparent.  3. The pressure chamber according to claim 1, characterized in that the multi-cell mesh is made of a cord (tape) forming a cell, each of which is similar in shape to a circle, for example, a hexagon.

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