[Thermal effects of epidural anesthetic block].

In a sample of 20 healthy men (ASA I) we studied the thermal effects induced after epidural anesthetic blockade with bupivacaine (0.625%) and their relationship with the level of sensitive blockade to puncture or to cold. After 30 min of epidural injection of bupivacaine the level of cephalic analgesia was D IX (D IX +/- 2 segments) and that of cold discrimination D VII (D VII +/- 2 segments) being the thermo-algesic differential blockade of 2 to 3 segments. During epidural anesthesia there was a significant increase in foot skin temperature (4.1 +/- 1 centigrade degrees, p less than 0.001) without any appreciable skin temperature change at the thorax, abdomen, thigh, and calves. It is concluded that epidural anesthesia with bupivacaine (0.625%) at a sensitive analgesic level D IX produces significant increases in skin temperature only at the foot. This indicates that the extension level of sympathetic blockade is lower that of the analgesia.