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ANESTHETIC PHARMACOLOGY

C₅₀ for Propofol-Remifentanil Target-Controlled Infusion and Bispectral Index at Loss of Consciousness and Response to Painful Stimulus in Chinese Patients: A Multicenter Clinical Trial

Zhipeng Xu, MD, PhD^*, Fang Liu, MD^*, Yun Yue, MD^*, Tiehu Ye, MD, Bingxi Zhang, MD, Mingzhang Zuo, MD, Mingjun Xu, MD^||, Rongrong Hao, MD, Yuan Xu, MD, Ning Yang, MD, and Xiangming Che, MD^||

From the *Beijing Chaoyang Hospital, Capital Medical University, Beijing, People’s Republic of China; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, People’s Republic of China; Beijing Tongren Hospital, Capital Medical University, Beijing, People’s Republic of China; Beijing Hospital, Chinese Academy of Medical Sciences, Beijing, People’s Republic of China; and ||Beijing Gynecology and Obstetrics Hospital, Capital Medical University, Beijing, People’s Republic of China.

Address correspondence and reprint requests to Yun Yue, Beijing Chaoyang Hospital, Capital Medical University, 8#, Baijiazhuang Rd., Chaoyang District, Beijing 100020, People’s Republic of China. Address e-mail to yueyun{at}hotmail.com.

BACKGROUND: In this study, we evaluated the predicted blood and effect-site C₅₀ for propofol and remifentanil target-controlled infusion and the Bispectral Index (BIS) values at loss of consciousness (LOC) and response to a standard noxious painful stimulus in Chinese patients. We hypothesized that these values would be different from previously published data on Caucasians.

METHODS: Five medical centers enrolled 405 ASA physical status I and II unpremedicated Chinese patients (97 men, 308 women) aged 18–65 yr. Propofol was initially given to a predicted blood concentration of 1.2 µg/mL and thereafter increased by 0.3 µg/mL every 30 s until Observer’s Assessment of Alertness and Sedation score was 1. The propofol was kept constant, and remifentanil was given to provide a predict blood concentration of 2.0 ng/mL, and then increased by 0.3 ng/mL every 30 s until loss of response to a tetanic stimulus. BIS (version 3.22, BIS Quattro sensor) was also recorded.

RESULTS: The propofol effect-site C₅₀ at LOC was 2.2 (2.2–2.3) µg/mL. The remifentanil effect-site C₅₀ at loss of response to painful stimulus was 3.3 ng/mL. Fifty percent of patients lost consciousness at a BIS value of 58, and 95% had lost consciousness at BIS values <40. The BIS value at C₅₀ at loss of response to painful stimulus was 65.4, which was higher than that at LOS (P < 0.001).

CONCLUSIONS: The predicted blood and effect-site concentrations of propofol and BIS values at LOC were lower than those in previously published studies of Caucasian populations.