Use of i.m. temperature probes during cardiopulmonary bypass in humans

I.m. temperature probes were used in humans during and after hypothermic cardiopulmonary bypass (CPB). After rewarming to apparent normothermia of the body core, we found that the temperature of the vastus lateralis muscle remained well below the nasopharyngeal temperature at the time of weaning from bypass. This reduced muscle temperature represents a considerable deficit in total body heat which may account for a large proportion of the afterdrop in temperature which occurs in the postoperative period. There was no morbidity associated with the use of the i.m. probes which could be incorporated into standard clinical practice.