Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.
Center for Systems Neuroscience Hannover, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.
BMC Vet Res. 2020 Sep 14;16(1):332. doi: 10.1186/s12917-020-02532-y.
The aim of this prospective and complete cross-over study was to evaluate the effects of isoflurane, remifentanil and dexmedetomidine on EEG parameters derived from the Narcotrend® Monitor before and after nociceptive stimulation at different isoflurane MAC (minimal alveolar concentration) multiples. Seven adult European Domestic Short Hair cats were used. Each cat went through 3 experimental treatments. Group I received isoflurane, group IR received isoflurane and a constant rate infusion (CRI) of remifentanil (18 μg/kg/h IV), and group ID received isoflurane and a CRI of dexmedetomidine (3 μg/kg/h IV). The isoflurane MAC in each group was determined via supramaximal electrical stimulation. The EEG parameters were derived by a Narcotrend Monitor at specific time points before and after nociceptive stimulation at 0.75, 1.0 and 1.5 MAC. The depth of anaesthesia was also assessed by a clinical score.
The mean MAC sparing effects in group IR and group ID were 9.8 and 55.2%, respectively. The best correlation of EEG and MAC multiples was found for the Narcotrend Index (NI) in group I (r = - 0.67). The NI was also able to differentiate between 0.75 MAC and 1.5 MAC in group IR. Spectral edge frequency had a lower correlation with MAC multiples in group I (r = - 0.62) but was able to differentiate between 0.75 MAC and 1.5 MAC in groups I and IR, and between 1.0 MAC and 1.5 MAC in group IR. Narcotrend Index, SEF 95 and MF increased significantly after nociceptive stimulation at 1.0 MAC in group I, and SEF 95 increased significantly at 0.75 MAC in group ID. The clinical score correlated closer than any of the EEG parameters with MAC in all groups, with highest correlation values in group I (r = - 0.89). Noxious stimulation led to a significant increase of the clinical score at 0.75 MAC and 1.0 MAC in group I.
The EEG parameters derived from the Narcotrend Monitor show correlation to isoflurane MAC multiples in cats, but the anaesthetic protocol and especially the addition of dexmedetomidine have great influence on the reliability. The Narcotrend Monitor can be used as an additional tool to assess anesthetic depth in cats.
本前瞻性、完全交叉研究的目的是评估异氟烷、瑞芬太尼和右美托咪定在不同异氟烷最小肺泡浓度（MAC）倍数下对伤害性刺激前后衍生自 Narcotrend® 监测仪的脑电图参数的影响。7 只成年欧洲短毛家猫被用于研究。每只猫接受 3 种实验处理。组 I 接受异氟烷，组 IR 接受异氟烷和瑞芬太尼持续输注（CRI）（18μg/kg/h IV），组 ID 接受异氟烷和右美托咪定 CRI（3μg/kg/h IV）。每组的异氟烷 MAC 通过超强电刺激确定。在伤害性刺激前和刺激后特定时间点，通过 Narcotrend 监测仪得出脑电图参数，在 0.75、1.0 和 1.5 MAC 下进行。麻醉深度也通过临床评分评估。
组 IR 和组 ID 的平均 MAC 节省效应分别为 9.8%和 55.2%。组 I 中发现脑电图和 MAC 倍数相关性最好的是 Narcotrend 指数（NI）（r=-0.67）。NI 也能区分组 IR 中的 0.75 MAC 和 1.5 MAC。在组 I 中，频谱边缘频率与 MAC 倍数的相关性较低（r=-0.62），但能区分 0.75 MAC 和 1.5 MAC，以及组 I 和组 IR 中的 1.0 MAC 和 1.5 MAC。在组 I 中，1.0 MAC 时伤害性刺激后 Narcotrend 指数、SEF95 和 MF 显著增加，在组 ID 中 0.75 MAC 时 SEF95 显著增加。在所有组中，临床评分与 MAC 的相关性均优于任何脑电图参数，在组 I 中相关性最高（r=-0.89）。伤害性刺激导致组 I 中的 0.75 MAC 和 1.0 MAC 时临床评分显著增加。
从 Narcotrend 监测仪得出的脑电图参数与猫的异氟烷 MAC 倍数相关，但麻醉方案，尤其是右美托咪定的添加对可靠性有很大影响。Narcotrend 监测仪可用作评估猫麻醉深度的附加工具。
