Fig. 2. Examples of log-linear serum R- and S- thiopental and R- and S- pentobarbital serum concentration–time curves shown for 5 patients. Note that the time scales are not uniform among the examples. The arrow indicates the time of completion of a thiopental infusion. □= R- thiopental, o = S- thiopental, += R- pentobarbital, x = S- pentobarbital. Lines are the non-linear model fits to data:---= R- thiopental, –= S- thiopental.