Figure 11-18 The reduction in isoflurane concentration to prevent movement at skin incision in 50% of patients by increasing measured remifentanil whole blood concentrations. F represents a patient who moved and S, a patient who did not move. The solid line is the logistic regression solution for a patient 40 years of age. (From Lang E, Kapila A, Shlugman D, et al: Reduction of isoflurane minimal alveolar concentration by remifentanil. Anesthesiology 85:721–728, 1996.)