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US 5,520,682 AGranted
Cryosurgical instrument with vent means and method using same
AssigneeCryomedical Sciences, Inc.
InventorsJohn G. Baust, ZhaoHua Chang, J. J. Finkelstein
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AssigneeCryomedical Sciences, Inc.
InventorsJohn G. Baust, ZhaoHua Chang, J. J. Finkelstein
Estimating the term…
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.
A method for producing sub-freezing temperatures sufficiently low to destroy living tissue by supplying a cryogenic liquid through an insulated passageway to a closed highly temperature conductive tip at the end of the passageway, said method comprising:
In a cryoprobe instrument including a probe casing having a closed distal end including a freezing zone for freezing live tissue and a proximal end for receiving liquid cryogenic refrigerant from an external source thereof, a cryogenic refrigerant supply tube having a supply tube inlet for receiving liquid cryogenic refrigerant at the proximal end and a supply tube outlet for delivering liquid cryogenic refrigerant from the proximal end to the freezing zone at the closed end, a cryogenic refrigerant exhaust channel surrounding the supply tube for transporting the used refrigerant from the closed end towards the proximal end, said exhaust channel having an exhaust channel inlet, and thermal insulation for insulating the side wall of the probe casing from the exhaust channel inlet to the proximal end, the improvement comprising vent means in the supply tube upstream of said freezing zone and located between the exhaust channel inlet and the supply tube inlet and in flow communication with the thermally insulated exhaust channel, thereby enabling during operation of the cryoprobe instrument gas formed or present in the supply tube to be vented to the exhaust channel.
A cryosurgical instrument which comprises a hollow probe tip having a closed end forming a freezing zone for freezing live tissue, a first inlet for receiving cryogenic liquid refrigerant and a first outlet for removing cryogenic refrigerant, a refrigerant supply tube for transporting cryogenic liquid refrigerant from the first inlet to the probe tip, said supply tube having ventilation means which prevents the free flow of refrigerant therethrough while allowing the ventilation of any gas present in the supply tube, an exhaust flow tube for transporting refrigerant from the freezing zone to the first outlet, wherein the supply tube and exhaust flow tube are arranged as concentric inner and outer tubes, with the supply tube forming the inner tube and extending beyond the outer tube in the freezing zone, and a thermal insulation chamber surrounding said concentric tubes and extending to the freezing zone, whereby the ventilation means is located upstream of said freezing zone and allows ventilation of any gas formed in the supply tube so as to maintain a high flow rate of refrigerant through the supply tube and to decrease the extent of counter-current heat exchange between the cryogenic refrigerant in the supply tube and the exhaust flow tube by allowing liquid refrigerant to vent to the exhaust flow tube and thereby cool the cryogenic refrigerant flowing through the exhaust tube.
A cryoprobe instrument comprising
A cryoprobe instrument comprising
In a cryoprobe instrument including a probe casing having a closed distal end forming a freezing zone for freezing live tissue and a handle portion at the proximal end, thereon cryogenic refrigerant supply passageway for transporting liquid cryogenic refrigerant from the proximal end to the freezing zone, a cryogenic refrigerant exhaust channel for transporting the used refrigerant from the freezing zone towards the proximal end, and thermal insulation for insulating the side wall of the probe casing from the freezing zone towards the proximal end, the improvement comprising vent means in at least the portion of the supply passageway surrounded by the thermal insulation and within the handle portion of the probe casing thereby enabling during operation gas formed or present in the supply passageway to be vented to the exhaust channel.
Dependencies are inferred from the claim text.