Motamed S, Klubien K, Edwardes M, Mazza L, Carli F
Department of Anesthesia, McGill University, Montreal, Quebec, Canada.
Anesthesiology. 1998 May;88(5):1211-8. doi: 10.1097/00000542-199805000-00011.
Mild hypothermia is accompanied by metabolic changes. Epidural local anesthetic agents attenuate the surgical stress response, but it is not known whether they modulate thermal stress.
Thirty patients undergoing colorectal surgery, performed by one surgical team, 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 induced 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 visual analogue score; and concentrations of epinephrine, norepinephrine, glucose, cortisol, lactate, and free fatty acids in plasma were measured before epidural blockade, 30 min after epidural blockade, at the end of surgery, and for 4 h after surgery. Patients and those measuring the outcomes were unaware of group allocation.
Core and mean skin temperatures decreased significantly in the control group (P < 0.001) but not in the warmed group. Catecholamine concentrations in plasma decreased significantly after epidural block, and although concentration 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 between the two groups for norepinephrine concentrations in plasma, body weight-adjusted oxygen consumption, pain visual analogue score, and metabolites.
The postoperative metabolic changes obtained with epidural block were similar except for an attenuated concentration of epinephrine in normothermic patients compared with those who were mildly hypothermic.
轻度低温伴有代谢变化。硬膜外局部麻醉药可减轻手术应激反应，但尚不清楚它们是否能调节热应激。
由一个手术团队为30例行结直肠手术的患者实施硬膜外0.5%布比卡因麻醉，以达到T3-S5感觉阻滞。然后将他们随机分为两组，每组15例。对照组或未加温组在手术期间任由体温下降，而加温组则采用主动加温。采用硫喷妥钠、维库溴铵、芬太尼、氧化亚氮和恩氟烷诱导全身麻醉。手术结束时，两组均接受硬膜外0.25%布比卡因以维持T5-L3感觉阻滞。在硬膜外阻滞前、硬膜外阻滞后30分钟、手术结束时以及术后4小时测量耳道（核心）温度和皮肤表面（15个部位）温度、耗氧量、疼痛视觉模拟评分以及血浆中肾上腺素、去甲肾上腺素、葡萄糖、皮质醇、乳酸和游离脂肪酸的浓度。患者和测量结果的人员均不知道分组情况。
对照组的核心温度和平均皮肤温度显著下降（P<0.001），而加温组则没有。硬膜外阻滞后血浆中儿茶酚胺浓度显著下降，尽管对照组手术结束时血浆中肾上腺素浓度较基线急剧升高（P=0.004），但加温组却下降了（P=0.007）。在恢复期间，两组在血浆去甲肾上腺素浓度、体重校正耗氧量、疼痛视觉模拟评分和代谢产物方面没有差异。
硬膜外阻滞术后的代谢变化相似，只是与轻度低温患者相比，体温正常患者的肾上腺素浓度有所降低。
