Table 1.

The target plasma concentrations of propofol and emergence time for each medical center.

medical center	Concentration of propofol (μg/ml)			Emergence time (min)
	LOC	End of surgery	ROC
1	1.8 ± 0.4	2.3 ± 0.5	1.1 ± 0.3	8 ± 3
2	3.8 ± 0.5	2.0 ± 0.4	0.7 ± 0.2	10 ± 3
3	3.0 ± 0.6	2.5 ± 0.3	1.1 ± 0.2	10 ± 5
4	3.1 ± 0.5	3.0 ± 0.5	0.8 ± 0.2	23 ± 10
5	2.5 ± 0.7	2.3 ± 0.5	1.1 ± 0.4	12 ± 7
6	2.8 ± 0.7	2.6 ± 0.5	1.4 ± 0.3	7 ± 2

Data are presented as mean ± SD.

Medical Center: 1, Tianjin Medical University General Hospital; 2, Beijing Friendship Hospital affiliated to Capital Medical University; 3, Beijing Chaoyang Hospital affiliated to Capital Medical University; 4, the Second Affiliated Hospital of Zhejiang University Medical College; 5, Changhai Hospital Affiliated to Second Military Medical University; 6, Xijing Hospital affiliated to the Fourth Military Medical University.

LOC: loss of consciousness. ROC: recovery of consciousness. Emergence time: from the end of anesthetic drugs infusion to ROC.