Fig. 3. Linear regression analysis of the concentrations of exhaled propofol and the plasma concentrations in 11 patients (24 total data points). Y-axis, average end-tidal exhaled propofol concentration of 50 breaths; x-axis, average plasma propofol concentration of five samples. Linear regression analysis was performed. The  solid line is the regression line, and the  broken lines indicate the 95% confidence interval.