Cryo-scalpel

Abstract

A method of cryogenic surgery and a scalpel suitable for the practice of the method. The scalpel has a hollow chamber within which a fluid medium may be injected, there being knife blade means in heat transfer contact therewith. In the practice of the method the scalpel is cooled by injection of an appropriate fluid. Thereafter animal tissue is cut with the scalpel thereby freezing the cut areas. The knife is heated as necessary to permit detachment of the scalpel from the frozen areas.

Description

BACKGROUND OF THE INVENTION

This invention relates to cryogenic surgery and more particularly to a scalpel which permits simultaneous cutting and freezing of tissue and to a method of using this scalpel.

It is known that for example in brain surgery and in the surgery of the prostate probes are used which are cooled by evaporating liquid nitrogen. In this case, the surrounding tissue is frozen after introducing the probe. After termination of the freezing process, the frozen tissue is removed in part or entirely by means of known techniques.

The application of this "bloodless" technique of operation when extended also to other organs or parts of the body, would allow intervention of any wanted size with minimum loss of blood and without interrupting the central blood supply to the field of operation. However, especially in the surgery of parenchymatous organs (kidney, liver, spleen etc.) it is not possible to freeze the whole organ before a surgical intervention or a separation of parts from the organ is made. In such cases, it is necessary to proceed to cutting and simultaneously start freezing of the cutting zones, in order to avoid secondary bleeding from the tissue. In addition it must be made sure that the instrument after termination of the freezing process is rapidly detached, without tearing the adhering tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view through one embodiment of a cryogenic scalpel according to the present invention.

FIG. 2 is a transverse sectional view of a modified embodiment of a scalpel according to the present invention and taken on a line corresponding to 2--2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and first to FIG. 1, the same shows a cryogenic scalpel according to the present invention which defines a hollow chamber 10 of generally triangular cross section. It has a planar base wall 12 and two slightly curved side walls, joined at one end to the base wall edges and curving toward each other and toward an apex forming a knife blade edge 18 which curves from a forward point 20 in which it is in contact with the chamber base wall 12 to a rearward point at which it meets the chamber end wall 22.

An outer tube 32 is secured to the chamber rear wall 22 at its forward end and extends in a direction generally parallel to the chamber base wall 12. An inner gas carrying tube 30 is mounted co-axially within, and spaced from, tube 32 by spacers 34. Tube 30 has its forward end extending through about two-thirds of the length of chamber 10, and its rear end terminates in a gas fitting 36. A suitable supply of liquefied gas, for example nitrogen, may be supplied to the tube and passed through the knife blade. By liquefied gas is meant a substance which is a gas at atmospheric pressure but is in the liquid state by virture of being at a higher than atmospheric pressure. Openings 38 are provided in the region of the wall of tube 30 which extends into the interior of chamber 10. The rear end of outer tube 32 is opened to the atmosphere. As a result, the pressure within chamber 10 is close to atmospheric. When liquefied gas is injected into the chamber, it rapidly evaporates and flows out to the atmosphere.

An insulated handle 40 is formed about the exterior of tube 32. This protects the hand of the user from the cold temperatures prevailing along the cryogenic scalpel. Handle 40 is hollow and, except for its end wall connections to tube 32 is spaced therefrom.

An electrical lead 42 passes through handle 40 and into chamber 10. Electrical lead 42 leads to resistance heater 44 which is positioned within the chamber in close adjacency to the side walls. When energized, they heat the chamber interior and with it the knife blade edge 18.

In the embodiment of FIG. 2, the side walls of the chamber do not actually meet each other. Instead, edges which are opposite to the base wall 12' meet to form a channel whose bottom wall 26 is curved along a line having approximately the same configuration as the apex forming the knife blade edge 18 described in connection with the embodiment of FIG. 1. The embodiment of FIG. 2 differs from that described in connection with FIG. 1 in that the knife blade means proper are constituted by an exchangeable blade 28 of platinum-iridium alloy, which blade is detachably mounted within the channel.

It will thus be seen that, in accordance with the present invention, the knife is, in principle, a miniature evaporation chamber, designed in the form of a knife blade (FIG. 1), which is cooled by the evaporation of liquefied gases.

The detachment of the blade from the firmly adhering tissue is obtained, after formation of a frozen zone which is sufficiently deep and large, either by internal electrical heating of the knife or by hot fluids admitted to its interior. Materials to be used for the manufacture of the knife are all metals or plastics suitable to be applied in the surgery of living tissue. The materials suitable for the blade are among others high stability metals or alloys, such as platinum-iridium. In a special construction the blade may be made exchangeable (FIG. 2).

An additional feature of the invention relates to a supplementary "freezing barrier," especially suited for operations of long duration, and which after cutting keeps the field of operation in a frozen state during any desired time. The freezing barrier consists essentially of two or more cold chambers which can be adjusted in such a way that the cold surfaces of these chambers will keep all cutting areas in a frozen state which have been previously produced by means of a cryo-scalpel. The freezing barrier is also provided with a heating device for detachment from the tissue.

Claims

We claim:

1. A cryogenic surgical scalpel, comprising a knife blade defining a hollow chamber, means for passing a fluid through said hollow chamber for cooling said knife blade, means connected to said knife blade for selectively heating said knife blade, said means for passing a fluid having an outer tube communicating with said chamber for providing an outlet for the fluid and an inner tube arranged coaxially within said outer tube and extending substantially across said chamber for providing an inlet for the fluid, said knife blade having two similar side walls in part defining a generally triangular cross section for said knife blade, the means for heating said knife blade having a resistance heater positioned with said chamber in close adjacency to said side walls, the region of the wall of said inner tube arranged within said chamber being spaced from said side walls and defining a plurality of openings, the scalpel further comprising an insulated handle formed about the exterior of said outer tube, the handle being hollow and having end walls which provide the only connections between said handle and said outer tube, and said resistance heater having leads passing through said insulated handle and into said chamber.

2. A scalpel as defined in claim 1, wherein said knife blade has an exchangeable blade.

3. A scalpel as defined in claim 2, wherein said knife blade defines a channel between said side walls, and said exchangeable blade is detachably mounted in said channel so as to be in heat transfer contact with said chamber.

4. A scalpel as defined in claim 1, wherein said side walls are slightly curved walls curving toward each other and toward an apex forming a knife blade edge, said knife blade having a base wall arranged between and joined to said side walls, and an end wall joined to said side walls and base wall, and wherein said knife blade edge curves from a forward point in which said knife blade edge is in contact with said base wall to a rearward point at which said knife blade edge meets said end wall.