Methods and systems for thermoregulation of injured tissue, medical specimens and other perishable materials are disclosed. Thermoregulation systems can comprise a thermoelectric device comprising a thermoelectric element within a flexible sleeve such that the sleeve can be applied circumferentially within an orthopedic positioner. Methods for shipping medical specimens under precise temperature control are disclosed by actively regulating the temperature within containers and at the surface of the specimen. Methods for treating injured tissue that demonstrate increased precision and control are disclosed.

A system for cooling a person includes a pump, a heat exchanger, a bladder, a thermometer, a heart rate variability (HRV) sensor, and a controller. The heat exchanger is in fluid communication with the pump. The bladder is configured to be placed on a person, and is in fluid communication with the heat exchanger. The thermometer measures a temperature of fluid passing through at least one of the pump, the heat exchanger and the bladder. The controller is in electrical communication with the thermometer, the HRV sensor and the heat exchanger, and is configured to control power delivered to or flow through the heat exchanger based on signals received from the HRV sensor.