Coste C, Guignard B, Menigaux C, Chauvin M
Department of Anesthesiology, Hôpital Ambroise Pare, Boulogne-Billancourt, France.
Anesth Analg. 2000 Jul;91(1):130-5. doi: 10.1097/00000539-200007000-00024.
We sought to determine whether the addition of nitrous oxide (N(2)O) to an anesthetic with propofol and remifentanil modifies the bispectral index (BIS) during the induction of anesthesia and orotracheal intubation. Thirty ASA physical status I or II patients were randomly allocated to receive either 50% air in oxygen (control group) or 60%-70% N(2)O in oxygen (N(2)O group) that was commenced via a mask simultaneously with the induction of anesthesia. Anesthesia was performed in all the patients with IV propofol at the target effect compartment site concentration of 4 microg/mL throughout the study. A target-controlled infusion (TCI) of remifentanil was initiated 3 min after the TCI of propofol and maintained at the effect-site concentration of 4 ng/mL until the end of the study. After loss of consciousness, and before the administration of vecuronium 0.1 mg/kg, a tourniquet was applied to one arm and inflated to a value more than the systolic blood pressure. An examiner, blinded to the presence of N(2)O, sought to detect any gross movement within the first minute after tracheal intubation, which was performed 10 min after remifentanil TCI began. Inspired and expired oxygen, N(2)O, and carbon dioxide were continuously monitored. A BIS value was generated every 10 s. Arterial blood pressure and heart rate (HR) were measured noninvasively every minute. Measures of mean arterial pressure (MAP), HR, and BIS were obtained before the induction, before the start of the remifentanil TCI, before laryngoscopy, and 5 min after intubation. No significant intergroup differences were seen in BIS, HR, and MAP throughout the study. Maximum changes in BIS, HR, and MAP with intubation were significant (P < 0.01) for both groups but comparable. Six patients in the control group and none in the N(2)O group moved after intubation (P < 0.05).
We demonstrated that 0.6 minimal alveolar concentration of nitrous oxide combined with a potent anesthetic and an opioid prevents movement after orotracheal intubation without affecting the bispectral index. This demonstrates that the bispectral index is not a useful neurophysiologic variable to monitor the level of anesthesia when nitrous oxide is added to a general anesthetic regimen using propofol and remifentanil.
我们试图确定在丙泊酚和瑞芬太尼麻醉诱导过程中添加氧化亚氮（N₂O）是否会改变脑电双频指数（BIS）以及经口气管插管时的情况。30例美国麻醉医师协会（ASA）身体状况I或II级的患者被随机分配，分别接受50%氧气和空气混合气体（对照组）或60% - 70%氧气和N₂O混合气体（N₂O组），通过面罩在麻醉诱导同时开始吸入。在整个研究过程中，所有患者均静脉注射丙泊酚，目标效应室浓度为4μg/mL。在丙泊酚靶控输注（TCI）3分钟后开始瑞芬太尼TCI，并维持效应室浓度为4ng/mL直至研究结束。意识消失后，在给予0.1mg/kg维库溴铵之前，在一侧手臂上应用止血带并充气至超过收缩压的值。一名对N₂O存在情况不知情的检查者试图在气管插管后第一分钟内检测到任何明显的肢体活动，气管插管在瑞芬太尼TCI开始10分钟后进行。持续监测吸入和呼出的氧气、N₂O和二氧化碳。每10秒记录一次BIS值。每分钟无创测量动脉血压和心率（HR）。在诱导前、瑞芬太尼TCI开始前、喉镜检查前以及插管后5分钟获取平均动脉压（MAP）、HR和BIS的测量值。在整个研究过程中，两组在BIS、HR和MAP方面未观察到显著的组间差异。两组插管时BIS、HR和MAP的最大变化均有统计学意义（P < 0.01），但具有可比性。对照组有6例患者在插管后出现肢体活动，N₂O组无患者出现（P < 0.05）。
我们证明，0.6最低肺泡有效浓度的氧化亚氮与强效麻醉药和阿片类药物联合使用可防止经口气管插管后出现肢体活动，且不影响脑电双频指数。这表明，当在使用丙泊酚和瑞芬太尼的全身麻醉方案中添加氧化亚氮时，脑电双频指数并非监测麻醉深度的有用神经生理变量。
