Delaunay L, Bonnet F, Liu N, Beydon L, Catoire P, Sessler D I
Département d'Anesthésie Réanimation, Hôpital Henri Mondor, Créteil, France.
Anesthesiology. 1993 Sep;79(3):470-4. doi: 10.1097/00000542-199309000-00009.
Clonidine stops postoperative shivering, but its underlying mechanism of action is unknown. Clonidine may impair central control of thermoregulation or act on peripheral receptors. Accordingly, the authors tested the hypothesis that clonidine reduces both the vasoconstriction and shivering thresholds, a pattern consistent with central thermoregulatory impairment.
Seven healthy volunteers participated in the study. Thermoregulatory vasoconstriction was evaluated using forearm minus fingertip, skin-temperature gradients; values exceeding 4 degrees C were considered to be significant vasoconstriction. Systemic oxygen consumption (VO2) was measured with a canopy system. In addition, shivering was qualitatively evaluated using a simple scale, graduated from 0 (no shivering) to 2 (intense shivering). The tympanic membrane temperatures triggering significant vasoconstriction and grade 1 shivering were considered to be the thresholds for the two thermoregulatory responses. Measurements were performed after a 10-min steady state period and during cooling by central venous infusion of Ringer's lactate solution at 4 degrees C. Each subject was evaluated at two sessions, separated by at least 48 h. They were randomly and blindly assigned to received either an intravenous bolus of 75 micrograms clonidine or a placebo before cooling. When the shivering score equaled 2, 75 micrograms clonidine was injected intravenously, and repeated if necessary, to completely stop shivering.
可乐定可阻止术后寒战，但其潜在作用机制尚不清楚。可乐定可能会损害体温调节的中枢控制或作用于外周受体。因此，作者检验了以下假设：可乐定降低血管收缩阈值和寒战阈值，这种模式与中枢体温调节受损一致。
7名健康志愿者参与了该研究。使用前臂减去指尖的皮肤温度梯度评估体温调节性血管收缩；超过4摄氏度的值被认为是显著的血管收缩。用面罩系统测量全身耗氧量（VO2）。此外，使用从0（无寒战）到2（强烈寒战）的简单量表对寒战进行定性评估。引发显著血管收缩和1级寒战的鼓膜温度被认为是两种体温调节反应的阈值。在10分钟的稳定期后以及通过中心静脉输注4摄氏度的乳酸林格液进行降温期间进行测量。每个受试者在两个时间段进行评估，间隔至少48小时。在降温前，他们被随机、盲法分配接受75微克可乐定静脉推注或安慰剂。当寒战评分等于2时，静脉注射75微克可乐定，必要时重复注射以完全停止寒战。
