Abstract: A method of cooling a material including the steps of (i) providing a cryotherapy instrument, (ii) positioning a portion of the cryotherapy instrument adjacent the material to be cooled, and (iii) circulating a cryogenic fluid through the cryotherapy instrument under physical conditions near a critical point of a liquid-vapor system for the cryogenic fluid. The critical point defines a point in a phase diagram of the liquid-vapor system where molar volumes are substantially equivalent for liquid and gas, whereby vapor lock associated with cooling of the cryotherapy instrument is avoided.

Abstract: A gas-based cryotherapy probe is provided with a shaft having a closed distal end adapted for insertion into a body. A supply conduit is disposed longitudinally within the shaft for flowing gas towards the distal end, and a return conduit is disposed longitudinally within the shaft for flowing gas from the distal end. The gas is maintained at a lower pressure within the return conduit than in the supply conduit. A heat exchanger is disposed within the shaft in thermal communication with the supply conduit and return conduit to exchange heat from gas in the supply conduit to gas in the return conduit. A vacuum jacket is adapted to provide thermal isolation of the heat exchanger from the shaft.

Abstract: Methods and systems are provided for cooling an object with a cryogen having a critical point defined by a critical-point pressure and a critical-point temperature. A pressure of the cryogen is raised above a pressure value determined to provide the cryogen at a reduced molar volume that prevents vapor lock. Thereafter, the cryogen is placed in thermal communication with the object to increase a temperature of the cryogen along a thermodynamic path that maintains the pressure greater than the critical-point pressure for a duration that the cryogen and object are in thermal communication.

Abstract: A gas-based cryotherapy probe is provided with a shaft having a closed distal end adapted for insertion into a body. A supply conduit is disposed longitudinally within the shaft for flowing gas towards the distal end, and a return conduit is disposed longitudinally within the shaft for flowing gas from the distal end. The gas is maintained at a lower pressure within the return conduit than in the supply conduit. A heat exchanger is disposed within the shaft in thermal communication with the supply conduit and return conduit to exchange heat from gas in the supply conduit to gas in the return conduit. A vacuum jacket is adapted to provide thermal isolation of the heat exchanger from the shaft.

Abstract: Methods and systems are provided for cooling an object with a cryogen having a critical point defined by a critical-point pressure and a critical-point temperature. A pressure of the cryogen is raised above a pressure value determined to provide the cryogen at a reduced molar volume that prevents vapor lock. Thereafter, the cryogen is placed in thermal communication with the object to increase a temperature of the cryogen along a thermodynamic path that maintains the pressure greater than the critical-point pressure for a duration that the cryogen and object are in thermal communication.

Abstract: A gas-based cryotherapy probe is provided with a shaft having a closed distal end adapted for insertion into a body. A supply conduit is disposed longitudinally within the shaft for flowing gas towards the distal end, and a return conduit is disposed longitudinally within the shaft for flowing gas from the distal end. The gas is maintained at a lower pressure within the return conduit than in the supply conduit. A heat exchanger is disposed within the shaft in thermal communication with the supply conduit and return conduit to exchange heat from gas in the supply conduit to gas in the return conduit. A vacuum jacket is adapted to provide thermal isolation of the heat exchanger from the shaft.

Abstract: Methods and systems are provided for cooling an object with a cryogen having a critical point defined by a critical-point pressure and a critical-point temperature. A pressure of the cryogen is raised above a pressure value determined to provide the cryogen at a reduced molar volume that prevents vapor lock. Thereafter, the cryogen is placed in thermal communication with the object to increase a temperature of the cryogen along a thermodynamic path that maintains the pressure greater than the critical-point pressure for a duration that the cryogen and object are in thermal communication.

Abstract: A cryotherapy system is provided with multiple cryoprobes, each of which has a shaft with a closed distal end adapted for insertion into a body and conduits for flowing a cryogenic fluid through the shaft to reduce a temperature of the distal end. A source is provided for the cryogenic fluid, and flow-control metering valves are provided in fluid communication with the conduits and source of the cryogenic fluid. A compressor is provided in fluid communication with the conduits of the cryoprobes to define a self-contained fluid system. The flow-control metering valves and the compressor are controlled by a computer processor to provide the desired flows of the cryogenic fluid through the conduits of the self-contained fluid system.

Abstract: A cryotherapy system is provided with multiple cryoprobes, each of which has a shaft with a closed distal end adapted for insertion into a body and conduits for flowing a cryogenic fluid through the shaft to reduce a temperature of the distal end. A source is provided for the cryogenic fluid, and flow-control metering valves are provided in fluid communication with the conduits and source of the cryogenic fluid. A compressor is provided in fluid communication with the conduits of the cryoprobes to define a self-contained fluid system. The flow-control metering valves and the compressor are controlled by a computer processor to provide the desired flows of the cryogenic fluid through the conduits of the self-contained fluid system.