Post-surgery epidural blockade with local anaesthetics attenuates the catecholamine and thermogenic response to perioperative hypothermia

Abstract

Core (aural canal) and mean skin (15 sites) temperatures, plasma adrenaline, noradrenaline and metabolites, and gaseous exchange were measured before, during and for 4 h after surgery in sixteen patients scheduled for elective colorectal surgery. All patients received general anaesthesia and no measures were taken to prevent the perioperative loss of body heat. At time of abdominal wall closure, when the core temperature was below 35.0 degrees C, the patients were randomly allocated to receive either 20-30 mg of papaveretum i.v. (papaveretum group, n = 8) or 15 ml of bupivacaine 0.75% via thoracic (T9) epidural route to obtain a T4-S5 sensory blockade (epidural group, n = 8). Continuous infusion of either i.v. papaveretum or epidural 0.25% bupivacaine was continued after surgery. During the recovery period of four hours the rate of increase in core and mean skin temperatures was significantly slower in the epidural group compared with the papaveretum group (P < 0.01). Plasma catecholamine concentrations remained elevated after surgery in the papaveretum group, whilst they decreased significantly once epidural blockade was established (P < 0.001). There was a lower trend, however not significant, in the rise of postoperative oxygen consumption and plasma glucose concentration in the epidural group compared with the papaveretum group.