Cryosurgical instrument

Abstract

A cryosurgical instrument includes a feed line for conveying fluid into an expansion chamber. The feed line has a capillary line section that terminates in the expansion chamber and forms an aperture for the fluid to undergo the Joule-Thomson effect. The flow cross-section of the feed line decreases in at least one transition section of the feed line in the form of a funnel. Following each transition section there preferably follows a step section, in which latter section the flow cross-section is preferably largely constant. The last step section is preferably formed by the capillary line section. Due to the acceleration of the fluid in the transition sections and the abating of pressure fluctuations in the capillary tube section and, optionally in the additional step sections, the expansion range in the expansion chamber is increased, without impeding the backflow of the expanded gas out of the expansion chamber.

What is claimed is: 
     
         1 . A cryosurgical instrument, comprising:
 a hollow shaft including a closed distal end with an outer adhesion surface for harvesting a tissue sample thereon and an expansion chamber disposed within the hollow shaft at the closed distal end thereof; and   a feed line disposed within the shaft for supplying a fluid into the expansion chamber, wherein the feed line has a capillary line section that extends along a longitudinal axis to a distal end of the feed line, wherein the distal end of the feed line is spaced from the closed distal end of the hollow shaft and terminates at a mouth opening disposed at an endmost distal extent of the feed line in the expansion chamber, wherein the mouth opening is spaced from the closed distal end of the hollow shaft and is oriented axially for supplying fluid distally into the expansion chamber;   wherein an inside diameter of the capillary line section is less than or equal to 200 μm.   
     
     
         2 . The cryosurgical instrument of  claim 1 , further comprising a return line disposed within the hollow shaft and fluidically connected to the expansion chamber for returning fluid out of the expansion chamber, wherein the return line is disposed entirely within the hollow shaft and extends around or adjacent to the feed line in a direction away from the expansion chamber for returning fluid out of the expansion chamber. 
     
     
         3 . The cryosurgical instrument according to  claim 2 , wherein the return line is defined by an exterior surface of the feed line and an interior surface of the hollow shaft. 
     
     
         4 . The cryosurgical instrument according to  claim 2 , wherein the feed line is arranged in or next to the return line, wherein a ratio of a flow cross-section of the return line with respect to an interior cross-section of the capillary line section is greater than or equal to 5. 
     
     
         5 . The cryosurgical instrument of  claim 1 , wherein a ratio of the inside diameter of the capillary line section with respect to a length of the capillary line section is between a minimum of 0.004 up to a maximum of 0.2. 
     
     
         6 . The cryosurgical instrument according to  claim 1 , wherein a distance between the mouth opening and an opposite wall surface of the expansion chamber ranges from 0.5 millimeters to 5 millimeters. 
     
     
         7 . The cryosurgical instrument according to  claim 1 , wherein a length of the capillary line section ranges from 1 millimeter to 15 millimeters. 
     
     
         8 . The cryosurgical instrument according to  claim 1 , wherein the feed line has a first section and a second section proximal to the capillary line section with different-size interior cross-sections and a tapered transition section from the first section to the second section in a direction of flow of the fluid toward the expansion chamber. 
     
     
         9 . A cryosurgical instrument, comprising:
 a hollow shaft including a closed distal end with an outer adhesion surface for harvesting a tissue sample thereon and an expansion chamber disposed within the hollow shaft at the closed distal end thereof; and   a feed line disposed within the shaft for supplying a fluid into the expansion chamber, wherein the feed line has a capillary line section that extends along a longitudinal axis to a distal end of the feed line, wherein the distal end of the feed line is spaced from the closed distal end of the hollow shaft and terminates at a mouth opening disposed at an endmost distal extent of the feed line in the expansion chamber, wherein the mouth opening is spaced from the closed distal end of the hollow shaft and is oriented axially for supplying fluid distally into the expansion chamber;   wherein a ratio of an inside diameter of the capillary line section with respect to a length of the capillary line section is between a minimum of 0.004 up to a maximum of 0.2.   
     
     
         10 . The cryosurgical instrument of  claim 9 , further comprising a return line disposed within the hollow shaft and fluidically connected to the expansion chamber for returning fluid out of the expansion chamber, wherein the return line is disposed entirely within the hollow shaft and extends around or adjacent to the feed line in a direction away from the expansion chamber for returning fluid out of the expansion chamber. 
     
     
         11 . The cryosurgical instrument according to  claim 10 , wherein the return line is defined by an exterior surface of the feed line and an interior surface of the hollow shaft. 
     
     
         12 . The cryosurgical instrument according to  claim 10 , wherein the feed line is arranged in or next to the return line, wherein a ratio of a flow cross-section of the return line with respect to an interior cross-section of the capillary line section is greater than or equal to 5. 
     
     
         13 . The cryosurgical instrument according to  claim 9 , wherein a distance between the mouth opening and an opposite wall surface of the expansion chamber ranges from 0.5 millimeters to 5 millimeters. 
     
     
         14 . The cryosurgical instrument according to  claim 9 , wherein a length of the capillary line section ranges from 1 millimeter to 15 millimeters. 
     
     
         15 . The cryosurgical instrument according to  claim 9 , wherein the feed line has a first section and a second section proximal to the capillary line section with different-size interior cross-sections and a tapered transition section from the first section to the second section in a direction of flow of the fluid toward the expansion chamber. 
     
     
         16 . A cryosurgical instrument, comprising:
 a hollow shaft terminating at a distal end;   a head receiving member having a proximal portion received in the distal end of the hollow shaft and a distal end portion;   a head member disposed on the distal end portion of the head receiving member, the head member including a closed distal end defining an expansion chamber and an outer adhesion surface for harvesting a tissue sample thereon; and   a feed line disposed within the hollow shaft for supplying a fluid into the expansion chamber, wherein the feed line has a capillary line section that extends along a longitudinal axis to a distal end of the feed line, wherein the distal end of the capillary line section is spaced from the closed distal end of the head member and terminates at a mouth opening disposed at an endmost distal extent of the capillary line section, wherein the mouth opening is spaced from the closed distal end of the head member and is oriented axially for supplying fluid distally into the expansion chamber.   
     
     
         17 . The cryosurgical instrument of  claim 16 , wherein the feed line tapers gradually from a proximal section to the capillary line section, wherein the proximal section has a larger interior cross-sectional area than an interior cross-sectional area of the capillary line section, wherein the proximal section is positioned proximal to the proximal portion of the head receiving member. 
     
     
         18 . The cryosurgical instrument of  claim 16 , wherein an inside diameter of the capillary line section is less than or equal to 200 μm. 
     
     
         19 . The cryosurgical instrument of  claim 16 , wherein the head member includes a cone-shaped interior surface that defines at least a portion of the expansion chamber. 
     
     
         20 . The cryosurgical instrument of  claim 16 , wherein, further comprising a return line disposed within the hollow shaft and fluidically connected to the expansion chamber for returning fluid out of the expansion chamber, wherein the return line extends around or adjacent to the feed line in a direction away from the expansion chamber for returning fluid out of the expansion chamber.