Twenty-eight patients were studied after uncomplicated
aortocoronary bypass surgery with hypothermic
cardiopulmonary bypass (CPB). In all patients residual
hypothermia was effectively treated by the use of extended
rewarming during CPB and postoperatively by an external heat source. This treatment almost eliminated postoperative shivering, and it resulted in the lowering of
oxygen uptake,
carbon dioxide production, and required ventilatory volumes to stable levels where spontaneous breathing could be used safely. The patients were divided into two groups. In group I (n = 12), intraoperative
anesthesia was based on an intravenous (IV)
opioid (
phenoperidine), which caused persistent
respiratory depression and made
mechanical ventilation necessary for a mean postoperative time period of 10.7 +/- 3.8 hours even with the
rewarming. In group II (n = 16), thoracic
epidural analgesia and intraoperative
general anesthesia with
enflurane were used. In this group, postoperative metabolic and ventilatory requirements were stable and low, finger skin temperature was normalized earlier, systemic vascular resistance was lower, and
stroke index was higher. Emergence from
anesthesia was uneventful and was achieved early postoperatively in Group II. The patients had good
pain relief and were mentally alert. Adequate spontaneous breathing was resumed quickly and endotracheal extubation was performed within the first two postoperative hours (1.6 +/- 0.5 hours). No complications or increased morbidity occurred, and no patient needed to be reintubated in Group II.