Ewen A, Archer D P, Samanani N, Roth S H
Department of Anaesthesia, University of Calgary, Alberta, Canada.
Can J Anaesth. 1995 Jun;42(6):532-40. doi: 10.1007/BF03011694.
Subhypnotic doses of thiopentone are considered to possess antianalgesic or hyperalgesic properties. In this study, we have tested the hypothesis that the coincidence of sedation and hyperalgesia is a property of both barbiturate and non-barbiturate anaesthetic agents. In a randomized, prospective, blinded study, the effects of slow (20 min) iv infusions of thiopentone, pentobarbitone, methohexitone or propofol on nociceptive threshold were measured in rats by tail pressure analgesimetry and compared with saline-infused control animals. Nociceptive thresholds were correlated with measurements of plasma drug concentrations and behavioural assessments. Comparison of pre-infusion nociceptive threshold with the lowest threshold obtained during drug infusion revealed decreases in all four treatment groups. As a percentage of the pre-infusion values, the decreases were: thiopentone: 42.5% (P < 0.001), pentobarbitone: 27.8% (P = 0.014), methohexitone: 24.9% (P = 0.013), propofol: 21.6% (P = 0.006). There were no changes in nociceptive threshold in the control groups. The relationship between nociceptive threshold and plasma drug concentration was usually characterized by an initial decline followed by a rise in nociceptive threshold as the plasma concentration and degree of sedation increased. The results support the hypothesis that hyperalgesia is a property of different anaesthetic agents when administered at sub-hynotic concentrations.
硫喷妥钠的亚催眠剂量被认为具有抗镇痛或痛觉过敏特性。在本研究中，我们检验了以下假设：镇静与痛觉过敏的同时出现是巴比妥类和非巴比妥类麻醉剂共有的特性。在一项随机、前瞻性、双盲研究中，通过尾压镇痛法测量了硫喷妥钠、戊巴比妥、美索比妥或丙泊酚缓慢（20分钟）静脉输注对大鼠伤害性感受阈值的影响，并与输注生理盐水的对照动物进行比较。伤害性感受阈值与血浆药物浓度测量值及行为评估相关。将输注前的伤害性感受阈值与药物输注期间获得的最低阈值进行比较，结果显示所有四个治疗组的阈值均降低。以输注前值的百分比计算，降低幅度分别为：硫喷妥钠：42.5%（P < 0.001），戊巴比妥：27.8%（P = 0.014），美索比妥：24.9%（P = 0.013），丙泊酚：21.6%（P = 0.006）。对照组的伤害性感受阈值无变化。伤害性感受阈值与血浆药物浓度之间的关系通常表现为随着血浆浓度和镇静程度增加，伤害性感受阈值先下降，随后上升。结果支持了以下假设：当以亚催眠浓度给药时，痛觉过敏是不同麻醉剂的一种特性。
