Hayashida Masakazu, Fukunaga Atsuo, Hanaoka Kazuo
From the *Department of Anesthesiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; and the †Department of Anesthesiology, Harbor/UCLA Medical Center, Torrance, California.
Anesth Analg. 2003 Nov;97(5):1340-1346. doi: 10.1213/01.ANE.0000083369.63589.A5.
With a traditional clamp test alone, quantitative evaluation of the level of surgical anesthesia/analgesia is not easy. We have developed a rabbit model that allows for repeated quantification of the varying level of surgical anesthesia/analgesia using both mechanical and electrical stimulation as simulated surgical stimuli. After tracheostomy and intravascular cannulations under isoflurane anesthesia, eight rabbits were placed on a sling that allowed for free movement of the head and extremities. The inspired isoflurane concentration was reduced from 3% to 1.5% and then to 0%. Remifentanil was then infused at 4 graded infusion rates (0.1-0.8 microg. kg(-1) x min(-1)). At each drug dose, analgesic variables were determined including the number of animals behaviorally unresponsive to clamping the forepaw (nonresponders) and threshold voltage of subcutaneous electrical stimulation (2 Hz, 5 Hz, and 50 Hz) required to evoke the head lift (HLT, pain detection/arousal threshold) and escape movement responses (EMT, pain tolerance threshold). With increasing drug doses, HLTs and EMTs at 5 Hz increased dose-dependently and most proportionately to increases in the number of nonresponders, a standard indicator of the anesthetic/analgesic level. Therefore, using the HLT and EMT at 5 Hz combined with a clamp test, this rabbit model allows for quantitative evaluation of the varying level of surgical anesthesia/analgesia.
We have developed a rabbit model of surgical anesthesia and analgesia using both mechanical and electrical stimulation as simulated surgical stimuli, which allows for repeated, quantitative, and qualitative evaluation of the varying level of surgical anesthesia and analgesia, differentiation between sedative/hypnotic and analgesic components of drug actions, and simultaneous monitoring of all the clinically relevant physiological variables including cardiovascular and respiratory variables.
仅通过传统的夹捏试验，很难对手术麻醉/镇痛水平进行定量评估。我们开发了一种兔模型，该模型能够使用机械和电刺激作为模拟手术刺激，对不同水平的手术麻醉/镇痛进行重复定量。在异氟烷麻醉下进行气管切开术和血管插管后，将八只兔子置于一个可使头部和四肢自由活动的吊带上。吸入的异氟烷浓度从3%降至1.5%，然后降至0%。随后以4个分级输注速率（0.1 - 0.8微克·千克⁻¹·分钟⁻¹）输注瑞芬太尼。在每个药物剂量下，测定镇痛变量，包括对夹捏前爪无行为反应的动物数量（无反应者）以及引发抬头（HLT，疼痛检测/觉醒阈值）和逃避运动反应（EMT，疼痛耐受阈值）所需的皮下电刺激（2赫兹、5赫兹和50赫兹）的阈值电压。随着药物剂量增加，5赫兹时的HLT和EMT呈剂量依赖性增加，且与无反应者数量的增加最为成比例，无反应者数量是麻醉/镇痛水平的标准指标。因此，使用5赫兹时的HLT和EMT并结合夹捏试验，该兔模型能够对不同水平的手术麻醉/镇痛进行定量评估。
我们开发了一种使用机械和电刺激作为模拟手术刺激的兔手术麻醉和镇痛模型，该模型能够对不同水平的手术麻醉和镇痛进行重复、定量和定性评估，区分药物作用的镇静/催眠和镇痛成分，并同时监测所有临床相关的生理变量，包括心血管和呼吸变量。
