METABOLIC CHANGES DURING RECOVERY IN NORMOTHERMIC VERSUS HYPOTHERMIC PATIENTS UNDERGOING SURGERY AND RECEIVING GENERAL-ANESTHESIA AND EPIDURAL LOCAL-ANESTHETIC AGENTS
S. Motamed et al., METABOLIC CHANGES DURING RECOVERY IN NORMOTHERMIC VERSUS HYPOTHERMIC PATIENTS UNDERGOING SURGERY AND RECEIVING GENERAL-ANESTHESIA AND EPIDURAL LOCAL-ANESTHETIC AGENTS, Anesthesiology, 88(5), 1998, pp. 1211-1218
Background: Mild hypothermia is accompanied by metabolic changes. Epid
ural local anesthetic agents attenuate the surgical stress response, b
ut it is not known whether they modulate thermal stress. Methods: Thir
ty patients undergoing colorectal surgery, performed by one surgical t
eam, received epidural 0.5% bupivacaine to achieve T3-S5 sensory block
. They were then assigned randomly to two groups of 15 patients each.
The control or unwarmed group was left to cool during surgery, whereas
active warming was used in the warmed group. General anesthesia was i
nduced by thiopentone, vecuronium, fentanyl, nitrous oxide in oxygen,
and enflurane. At the end of surgery, both groups received epidural 0.
25% bupivacaine to maintain a T5-L3 sensory block. Aural canal (core)
and skin surface (15 sites) temperatures; oxygen consumption; pain vis
ual analogue score; and concentrations of epinephrine, norepinephrine,
glucose, cortisol, lactate, and free fatty acids in plasma were measu
red before epidural blockade, 30 min after epidural blockade, at the e
nd of surgery, and for 4 h after surgery. Patients and those measuring
the outcomes were unaware of group allocation. Results: Core and mean
skin temperatures decreased significantly in the control group (P < 0
.001) but not in the warmed group. Catecholamine concentrations in pla
sma decreased significantly after epidural block, and although concent
ration of epinephrine in plasma increased from baseline sharply in the
control group at the end of surgery (P = 0.004), it decreased in the
warmed group (P = 0.007). During recovery, there was no difference bet
ween the two groups for norepinephrine concentrations in plasma, body
weight-adjusted oxygen consumption, pain visual analogue score, and me
tabolites. Conclusions: The postoperative metabolic changes obtained w
ith epidural block were similar except for an attenuated concentration
of epinephrine in normothermic patients compared with those who were
mildly hypothermic.