The present invention provides a medical system, including a catheter defining an injection lumen, a chamber in fluid communication with the injection lumen, and an exhaust lumen in fluid communication with the chamber; a first temperature sensor positioned in the exhaust lumen proximal to the chamber; a second temperature sensor positioned in the chamber; and a console in electrical communication with the first and second temperature sensors, the controller modifying coolant flow through the medical device based at least in part upon a signal received from the first and second temperature sensor. The system may further include a thermally-conductive element circumscribing a substantial portion of the exhaust lumen proximal to the chamber, where the first temperature sensor is mounted to the thermally-conductive element, and the thermally-conductive element may include at least one of a braid, coil, and band.