Fig. 4. Response of heart rate (HR) to gastroscope insertion in various age groups as a function of propofol plasma concentration. Filled circles = HR values before insertion; open circles = HR values after insertion. Solid lines show concentration–response regressions and 95% confidence intervals for HR before insertion, and dotted lines indicate those after insertion. The correlation coefficient, r, to these lines is indicated. Vertical arrows indicate Cp50endo and Cp95endo values of propofol for various age groups.