Barter Linda S, Hawkins Michelle G, Pypendop Bruno H
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
Am J Vet Res. 2015 Feb;76(2):111-5. doi: 10.2460/ajvr.76.2.111.
To determine effects of increasing plasma fentanyl concentrations on the minimum alveolar concentration (MAC) of isoflurane in rabbits.
6 adult female New Zealand White rabbits (Oryctolagus cuniculus).
Rabbits were anesthetized with isoflurane in oxygen; ventilation was controlled and body temperature maintained between 38.5° and 39.5°C. Fentanyl was administered IV by use of a computer-controlled infusion system to achieve 6 target plasma concentrations. Isoflurane MAC was determined in duplicate by use of the bracketing technique with a supramaximal electrical stimulus. Blood samples were collected for measurement of plasma fentanyl concentration at each MAC determination. The MAC values were analyzed with a repeated-measures ANOVA followed by Holm-Sidak pairwise comparisons.
Mean ± SD plasma fentanyl concentrations were 0 ± 0 ng/mL (baseline), 1.2 ± 0.1 ng/mL, 2.2 ± 0.3 ng/mL, 4.4 ± 0.4 ng/mL, 9.2 ± 0.4 ng/mL, 17.5 ± 2.6 ng/mL, and 36.8 ± 2.4 ng/mL. Corresponding mean values for isoflurane MAC were 1.92 ± 0.16%, 1.80 ± 0.16%, 1.60 ± 0.23%, 1.46 ± 0.22%, 1.12 ± 0.19%, 0.89 ± 0.14%, and 0.70 ± 0.15%, respectively. Isoflurane MAC for plasma fentanyl concentrations ≥ 2.2 ng/mL differed significantly from the baseline value. In 3 rabbits, excessive spontaneous movement prevented MAC determination at the highest plasma fentanyl concentration.
Fentanyl reduced isoflurane MAC by approximately 60% in New Zealand White rabbits. Further studies will be needed to investigate the cardiorespiratory effects of isoflurane and fentanyl combinations in rabbits; however, fentanyl may prove to be a useful adjunct to inhalation anesthesia in this species.
确定兔血浆中芬太尼浓度升高对异氟烷最低肺泡有效浓度（MAC）的影响。
6只成年雌性新西兰白兔（穴兔）。
兔用异氟烷在氧气中麻醉；控制通气并将体温维持在38.5℃至39.5℃之间。使用计算机控制的输注系统静脉注射芬太尼以达到6个目标血浆浓度。采用最大刺激强度的括入法重复测定异氟烷MAC。每次测定MAC时采集血样以测量血浆芬太尼浓度。MAC值采用重复测量方差分析，随后进行霍尔姆-西达克两两比较分析。
血浆芬太尼浓度的平均值±标准差分别为0±0 ng/mL（基线）、1.2±0.1 ng/mL、2.2±0.3 ng/mL、4.4±0.4 ng/mL、9.2±0.4 ng/mL、17.5±2.6 ng/mL和36.8±2.4 ng/mL。相应的异氟烷MAC平均值分别为1.92±0.16%、1.80±0.16%、1.60±0.23%、1.46±0.22%、1.12±0.19%、0.89±0.14%和0.70±0.15%。血浆芬太尼浓度≥2.2 ng/mL时的异氟烷MAC与基线值有显著差异。在3只兔中，在最高血浆芬太尼浓度时出现过度的自主运动而无法测定MAC。
在新西兰白兔中，芬太尼使异氟烷MAC降低约60%。需要进一步研究来调查异氟烷和芬太尼联合应用对兔心肺的影响；然而，芬太尼可能被证明是该物种吸入麻醉的一种有用辅助药物。
