Figure 11-20 A computer simulation of the time course of remifentanil concentration change, when the dosage regimen is calculated based on the lean body mass (LBM) or total body weight (TBW) for both obese and lean patients. Note that TBW-based dosing in an obese patient results in dramatically higher concentrations. (From Egan TD, Huizinga B, Gupta SK, et al: Remifentanil pharmacokinetics in obese versus lean patients. Anesthesiology 89:562–573, 1998.)