Figure 2. Comparative effects of increasing concentrations of anesthetic on isometric contractions of human atrial tissue induced by field stimulation. Data are mean+/-SEM. Curves were plotted using logistic regression. Hatched squares indicate the clinical concentration range during anesthesia. Coarse hatching (left) represents the total concentration and fine hatching (right) shows the free fraction. (A) Propofol (n = 16). (B) Thiopental (n = 7). (C) Midazolam (n = 7). (D) Ketamine (n = 9). (E) Etomidate (n = 9). (F) Combined plot showing the concentration-response curve of the five anesthetics. For statistical analysis, see Table 1.