Figure 12-32 Comparison of manual versus closed-loop anesthetic control on the time course of return of spontaneous ventilation (A), eye opening (B), extubation (C), and orientation (D). In each case, the more rapid curve is the closed-loop control, and the slower curve is the manual control. (Adapted from Struys MM, De Smet T, Versichelen LF, et al: Comparison of closed-loop controlled administration of propofol using Bispectral Index as the controlled variable versus "standard practice" controlled administration. Anesthesiology 95:6–17, 2001.)