The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 28, 1996
Filed:
Mar. 06, 1995
John G Baust, Candor, NY (US);
ZhaoHua Chang, Poolesville, MD (US);
J J Finkelstein, Bethesda, MD (US);
Cryomedical Sciences, Inc., Rockville, MD (US);
Abstract
A closed end surgical cryoprobe instrument may have a probe shaft diameter of 3 millimeters or less and can achieve and maintain freezing zone temperatures close to that of the liquid cryogenic refrigerant. Using sub-cooled liquid nitrogen at approximately -208.degree. C. freezing zone temperatures as low as -206.degree. C. can be achieved in under 1 minute. The liquid nitrogen supply tube is provided with a plurality of small vent holes to vent gas formed or present in the refrigerant supply tube to the return refrigerant flow channel. The vent holes also allow small amount of liquid nitrogen to vent into the return flow channel to further reduce the temperature differential between the sub-cooled liquid nitrogen supply and the counter current flowing return refrigerant. Heat transfer is maintained through nucleate boiling. In place of vent holes, narrow slits may be provided in the supply tube. Alternatively, a sintered porous metal supply tube can be used as the vent means.