Ketamine wash-in/wash-out profiles of each study after a 1-min bolus infusion of 0.5 mg/kg in a 70-kg individual. Red lines represent models based on arterial samples, and blue lines represent models based on venous samples. (A) One-compartment models from one study. (B) Two-compartment models from seven studies. (C) Three-compartment models from nine studies along with the curve (green line) based on the three-compartmental meta-analytical model. (D) Overall mean with the 95% CI for each evaluation of the arterial versus venous models.