Flaishon R, Windsor A, Sigl J, Sebel P S
Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, USA.
Anesthesiology. 1997 Mar;86(3):613-9. doi: 10.1097/00000542-199703000-00013.
Currently, there exists no effective monitor that can predict the probability of a patient being conscious during general anesthesia. The electroencephalogram-derived bispectral index (BIS) is a promising new method to assess anesthetic adequacy. This study used the BIS to predict the probability of recovery of consciousness after a single bolus induction dose of propofol or thiopental.
Twenty unpremedicated surgical patients were anesthetized with 4 mg/kg thiopental and 20 patients with 2 mg/kg propofol. The BIS was monitored throughout the study. After induction, before administration of neuromuscular blocking agent, a tourniquet was applied to one arm and inflated above the systolic blood pressure. This allowed preservation of the ability to move the hand after neuromuscular blocking agent onset. Patients were then prompted to squeeze the investigator's hand every 30 s, until they responded to the request. At the time of response, anesthesia was reinduced and the study terminated.
The BIS at loss of consciousness and recovery of a response was not statistically different between propofol and thiopental. No patient with a BIS less than 58 was conscious. In both groups, a BIS of less than 65 signified a less than 5% probability of return of consciousness within 50 s.
The BIS can be used to predict probability of recovery of consciousness after a single injection of either thiopental or propofol.
目前，尚无有效的监测手段能够预测患者在全身麻醉期间恢复意识的可能性。脑电图双频谱指数（BIS）是一种评估麻醉深度的很有前景的新方法。本研究采用BIS来预测单次推注异丙酚或硫喷妥钠后意识恢复的可能性。
20例未用术前药的手术患者用4mg/kg硫喷妥钠麻醉，20例患者用2mg/kg异丙酚麻醉。在整个研究过程中监测BIS。诱导后，在给予神经肌肉阻滞剂之前，在一侧手臂上使用止血带并充气至收缩压以上。这使得在神经肌肉阻滞剂起效后仍保留手部运动能力。然后要求患者每30秒挤压研究者的手，直到他们对该要求做出反应。在做出反应时，重新诱导麻醉并终止研究。
异丙酚组和硫喷妥钠组在意识消失和恢复反应时的BIS无统计学差异。BIS低于58的患者均未恢复意识。在两组中，BIS低于65表明在50秒内恢复意识的可能性小于5%。
BIS可用于预测单次注射硫喷妥钠或异丙酚后意识恢复的可能性。
