Cryosurgical apparatus and method

Cryosurgical apparatus for necrosing human tissue or the like, said apparatus comprising

• a coolant supply where said coolant is disposed within a container as a liquid under its own vapor pressure;
• a cryosurgical instrument having a hollow tissue contacting portion and a coolant expansion means disposed at the distal end of a feed passageway and a discharge path disposed outside of said passageway, both said feed passageway and said discharge path being disposed within said hollow tissue contacting portion;
• means for supplying said coolant to the first passageway of said cryosurgical instrument so that the coolant expanded through said expansion means lowers the temperature of said tissue contacting portion to a necrosing temperature sufficient to effect said necrosing of said human tissue or the like;
• and
• means connected to said discharge path for exhausting said coolant from said apparatus;
• switchable valve means connected to said discharge path of said cryosurgical instrument, said switchable valve means being switchable to a first position to exhaust said coolant from said apparatus and to a second position for closing the switchable valve means;
• defrost discharge means also connected to said discharge path of said cryosurgical instrument, the flow impedance of said defrost discharge means being substantially greater than that of said switchable valve means when it is in its said first position and substantially less than that of the switchable valve means when it is in its said second position,
• whereby the coolant is supplied to said feed passageway of said cryosurgical instrument for both a freeze mode and a defrost mode of operation of said apparatus, said apparatus being in its freeze mode when said switchable valve means is in its first position so that said coolant discharges through said switchable valve means and said apparatus being in its defrost mode when it is in its second position so that said coolant discharges through said defrost discharge means and where the temperature of said tissue contacting portion in the defrost mode is greater than 0.degree. C. as long as said apparatus is in the latter mode.

Cryosurgical method comprising the steps of

• providing a coolant supply container where a coolant selected from the groups consisting of nitrous oxide, carbon dioxide, Freon 13 or Freon 23 is disposed within a container in its liquid and gaseous phases, the critical temperature of said coolant being greater than the ambient temperature of the container;
• maintaining said vapor pressure at approximately at least what it is at said ambient temperature of the coolant supply;
• providing a cryosurgical instrument having a coolant expansion means disposed at the distal end of a feed passageway, and
• supplying said coolant to the feed passageway of said cryosurgical instrument so that the temperature of the coolant discharged through said expansion means is lowered,
• whereby said vapor pressure is maintained at approximately at least what it is at said ambient temperature during said supplying of the coolant to the feed passageway of the cryosurgical instrument.

Cryosurgical apparatus comprising

• a coolant supply where a coolant selected from the groups consisting of nitrous oxide, carbon dioxide, Freon 13 or Freon 23 is disposed within a container as a liquid due to the pressure of its own vapor where the critical temperature of said coolant is greater than the ambient temperature of the container;
• pressure maintaining means for maintaining said pressure of the vapor at approximately at least what it is at said ambient temperature of the container;
• a cryosurgical instrument having a coolant expansion means disposed at the distal end of a feed passageway;
• and
• means for supplying said coolant to the feed passageway of said cryosurgical instrument so that the temperature of the coolant discharged through said expansion means is lowered
• whereby said pressure maintaining means maintains said vapor pressure at approximately at least what it is at said ambient temperature during said supplying of the coolant to the feed passageway of the cryosurgical instrument.

Cyrosurgical apparatus comprising

• a coolant supply where a coolant selected from the groups consisting of nitrous oxide, carbon dioxide, Freon 13 or Freon 23 is disposed within a container as a liquid due to the pressure of its own vapor, said pressure being at a first value;
• a cryosurgical instrument having a coolant expansion means disposed at the distal end of a feed passageway;
• a supply line for supplying said coolant from said supply container to the feed passageway of said cryosurgical instrument so that the temperature of the coolant discharged through said expansion means is lowered;
• and
• pressure maintaining means including means externally disposed with respect to said container for heating the coolant for maintaining the vapor pressure of the coolant in the supply container at approximately at least said first value to thereby at least replace the heat lost by evaporation of the coolant in the container as coolant is delivered to the cryosurgical instrument.