BACKGROUND: Induction of hypothermia (a 4 °C decrease from baseline) improves outcomes in adult cardiac arrest and neonatal hypoxic ischemic encephalopathy, and may benefit other conditions as well. Methods used to implement or prevent hypothermia typically require skin contact with blankets or pads or intravascular access with catheter devices. The study was to evaluate the potential to induce mild therapeutic hypothermia via an esophageal route in a porcine model.METHODS: Single-animal proof-of-concept study of a prototype esophageal device in a 70 kg Yorkshire swine. We measured the rate of temperature change after placement of a prototype device to induce hypothermia via the esophagus, and compared this rate to known temperature changes that occur under similar laboratory conditions without a hypothermic device.RESULTS: Swine temperature decreased from a starting temperature of 37.8 °C to 33.8 °C (achieving the goal of a 4 °C decrease) in 175 minutes, resulting in a cooling rate of 1.37 °C/h. Histopathology of the esophagus showed normal tissue without evidence of injury.CONCLUSION: A prototype of an esophageal cooling device induced hypothermia effectively in a large single-swine model.