The authors report on the first 100 of a series of patients who have undergone open heart surgery while in a state of hypothermia induced by external ice-baths. Circulatory occlusion was maintained as long as 15 minutes at rectal temperatures of 26° to 28° C. by removing the carbon dioxide absorber from the respiratory circuit and allowing the CO2 to accumulate up to concentrations of 3 to 5%. Above 28° C. ventricular fibrillation occurred 12 times in hyperventilated patients; below 28° C., with added CO2, no fibrillation occurred. Heart failure occurred in 3 of 65 patients who were digitalized and in 24 of 35 patients who were not. No complications occurred during induction of hypothermia or during the subsequent rewarming.
Willard J. Zinn, Ernest H. Warnock. Safe HypothermiaA Report on the Use of External Ice-Baths in Open Heart Surgery on One Hundred Patients. JAMA. 1960;174(3):284–286. doi:10.1001/jama.1960.03030030064012