Title:
APPARATUS FOR APPLICATION OF LOCAL HYPOTHERMY TO THE KIDNEY
United States Patent 3738372


Abstract:
An apparatus for the application of local hypothermy to the kidney, comprising a kidney-cooling heat exchanger made as a confined chamber whose inside surface is so shaped as to suit the renal shape. The walls of the cooling heat exchanger are made double for the refrigerant to circulate therebetween, and fabricated from an elastic material.



Inventors:
SHIOSHVILI T
Application Number:
05/217565
Publication Date:
06/12/1973
Filing Date:
01/13/1972
Assignee:
SHIOSHVILI T,SU
Primary Class:
International Classes:
A61F7/12; A61F7/00; A61F7/10; (IPC1-7): A61F7/00
Field of Search:
128/400,402,258,403
View Patent Images:
US Patent References:
3238944Temperature controlling device for living organs1966-03-08Hirschhorn
3091242Apparatus for local hypothermia1963-05-28Johnson et al.
2260134Body pad1941-10-21Ballman
1896953Electric ice cap1933-02-07Hassell



Primary Examiner:
Trapp, Lawrence W.
Claims:
I claim

1. An apparatus for the application of local hypothermy to the kidney, comprising: a cooling heat exchanger made as a confined chamber whose inside surface is so shaped as to suit the renal shape; double walls of said cooling heat exchanger adapted for the refrigerant to circulate therebetween and made of an elastic material; a recess made in said cooling heat exchanger for the kidney to accommodate; a refrigerant tank; a pump for the refrigerant to recirculate between said tank and said cooling heat exchanger.

2. An apparatus as claimed in claim 1, wherein said double walls of the cooling heat exchanger are made of rubber.

Description:
This invention relates generally to the art of medicine and has particular reference to apparatus for applying local hypothermy to the kidney excluded from the blood circulation.

Known in the present day medical practice is an apparatus for applying local hypothermy to the kidney, comprising a heat-exchanger to cool down the kidney, which is essentially a big-diameter plastic tube, wherealong refrigerant or cooling agent is free to circulate. The tube embraces the kidney as a ring and due to being in permanent contact therewith, cools it down.

However, said known apparatus suffers from the disadvantage that the distal margin, the portal region or the hilum renis and partly the poles of the kidney, i.e., about 30 percent its external surface, prove to be out of contact with the cooling tube, which results in an inadequate cooling of the kidney and, consequently, in a low rate of cooling thereof.

Another apparatus of the character set forth above is now known to be used, wherein the heat exchanger is made as two hemispheres formed by a coiler element made of a plastic tube, wherealong refrigerant is under circulation. The kidney being cooled, when placed in between said hemispheres, is in contact with the heat exchanger with but separate areas of its outer surface, this being due to the spherical-shape heat exchanger that is out of correspondence with the shape of the kidney and, besides, due to the fact that the tubes forming the hemispheres, contact the kidney only along the tangential lines.

One more apparatus for the application of hypothermy to the kidney is known to use heretofore, wherein the heat exchanger is composed of two stainless-steel members forming a confined space or chamber, said members being kidney-shaped and having double walls for the refrigerant to circulate therebetween.

A disadvantage inherent in the aforesaid heat exchanger resides in the fact that even a great number of diversely shaped heat exchangers will fail to cover a variety of sizes and shapes of the renal curvature with the result that said heat exchangers provide the contact of the kidney with the walls of the heat exchanger only at some separate points.

Thus, due to inadequate contact with the surface, none of the hitherto known apparatus is capable of uniformly reducing the temperature of the kidney from 37° down to 20°C within a period of time shorter than 8-10 minutes.

Such a low rate of cooling is undesirable not only on account of the fact that is prolongs the period of useless ischaemia and delays the operation but, largely, due to the fact that low cooling rate of the kidney being operated prolongs the period of discrepancy between high energy demand of the renal tissue and a limited amount of energy sources. Thus, even a 8-10 -minute period of renal ischaemia occurring in an inadequately cooled kidney, entails adverse functional sequelae; therefore, cutting down of the cooling period by every minute is conducive to the successful outcome of the operation.

On the other hand, too high a cooling rate attainable due to the use of more frigorific refrigerants may inflict cold injury upon the kidney (cold ulcers, spasms of blood vessels); that is why the optimal way of maximum acceleration of the cooling rate is the attaining of a full contact of the refrigerant with the renal surface and, thereby, more complete heat transfer process.

It is therefore an essential object of the present invention to provide such an apparatus for the application of local hypothermy to the kidney that would comprise a heat exchanger capable of an adequate and safeful cooling of the human kidney of any size and configuration, this being due to a complete adherence of the walls thereof to the entire external renal surface and more perfect heat transfer process.

Said object is accomplished due to the fact that in an apparatus for the application of local hypothermy to the kidney, comprising a cooling heat exchanger made as a confined space or chamber having double walls for the refigerant to circulate therebetween and the inside surface whose shape corresponds to the renal shape, and also incorporating a reservoir for the refrigerant to hold and a pump for the refrigerant to recirculate between the cooling heat exchanger and the refrigerant-containing reservoir, according to the invention the walls of the cooling heat exchanger are made of an elastic material.

It is expedient that the walls of the cooling heat exchanger be made of rubber.

In the herein-proposed apparatus, when the heat exchanger is moderately filled with refrigerant, a close adherence of the inside surface thereof to the kidney is attained, which establishes the best conditions for a uniform, quick and safe heat transfer to occur. This enables a 3-4 fold increase in the renal cooling rate as compared to the best of the hitherto-known apparatus of similar purpose.

The apparatus is able to adequately and safely cool the kidney of an adult from 37° down to 20° within 2-3.5 minutes and the kidney of a child, for 1-1.5 minutes. When used in experiments on dogs the apparatus is instrumental in cooling down the kidney from 37° to 5°C for 4-5 minutes.

In what follows the invention is made more apparent from the disclosure of an exemplary embodiment thereof to be read in conjunction with the accompanying drawings, wherein:

FIG. 1 diagrammatically illustrates an apparatus for the application of local hypothermy to the kidney, according to the invention;

FIG. 2 is an enlarged-scale view of the heat exchanger of the apparatus, showing its wall partly cut away, according to the invention; and

FIG. 3 is a diagrammatic cross-sectional view of the heat-exchanger walls, taken through the refrigerant-carrying tubes, according to the invention.

Now referring to the Drawings, the apparatus for the application of local hypothermy to the kidney comprises a refrigerant tank 1 which is essentially a Dewar vacuum flask provided with a union 2 at the bottom thereof, connected to a rubber tube 3 part of which is accommodated inside the housing of a rotary roller pump 4. Rollers 5 of the pump 4 with their spindles 6 are fixed to a hub 7 set on a shaft 8 of a speed reducer 9; the latter is connected to a shaft 10 of an electric motor 11.

The apparatus comprises also a heat exchanger 12 having double walls constituted by an outside elastic jacket 13 (FIGS. 2,3) and an inside elastic jacket 14, The walls of the heat exchanger 12, when joined together round the entire perimeter, form a confined chamber whose inner surface is shaped to suit the shape of a kidney. A space 15 confined in between the elastic jackets 13 and 14 communicates with the tube 3 running from the rotary roller pump 4 and with a tube 16 through which the space 15 communicates with the tank 1, both of the tubes 3 and 16 being connected to the space 15 in such a way as to let the refrigerant fill the entire space 15.

A wedge-like recess 17 (FIG. 2) made in the heat exchanger 12 is for convenience in the application of a clamp to the vascular pedicle or the crus renis.

The heat exchanger 12 has also slots 18 to facilitate fitting of the heat exchanger 12 onto the kidney.

The apparatus for the application of local hypothermy to the kidney operates as follows.

The tank 1 (FIG. 1) is filled with the refrigerant, viz., a 96-percent ethanol cooled down to -15°C.

Then the electric motor 11 is switched on to impart rotation via the speed reducer 9 to the hub 7 connected to the rollers 5. The rollers 5 ride on the tube 3 in the direction indicated with the arrow in the Figure, thus forcing said tube to the inner wall of the housing of the rotary roller pump 4. As a result, the refrigerant from the tank 1 is forced out along the tube 3 to the heat exchanger 12 which is fitted onto the kidney being cooled. From the heat exchanger 12 the refrigerant flows along the tube 16 to return into the tank 1. The refrigerant passing through the space 15 (FIG. 2) of the heat exchanger 12 and the surface of the heat exchanger 12 contacting the kidney, have a temperature from +1 to +3°C.

The degree of filling of the space 15 of the heat exchanger 12 with the refrigerant depends upon the extent to which the tube 16 is compressed or pinched. When the space 15 is moderately filled with the refrigerant, the inner elastic jacket 14 of the heat exchanger 12 is made to snugly fit to the kidney over the entire surface thereof which provides for the best conditions for an adequate and rapid heat extraction from the kidney to apply hypothermy thereto.

The elastic jackets 13 and 14 of the heat exchanger 12 are made of rubber, their optimum thickness being 0.4-0.7 mm which enables both the required strength and heat conductance of the walls of the heat exchanger 12 to be attained.

The use of rubber as the material of the heat exchanger is due to its high elasticity and resilience which makes it possible to easily control the degree of filling of the heat exchanger 12 during the operation of the apparatus to suit the size and shape of the kidney being cooled.