A Prospective Study of Marsh PK-PD Model and Schnider PK-PD Model During Anesthesia Induction for Obese Patients...

This prospective study compared the Marsh and Schnider pharmacokinetic models for propofol target-controlled infusion (TCI) during anesthetic induction in obese patients undergoing elective cardiac surgery. A total of 118 patients were randomly assigned to either the Marsh or Schnider group (n = 59 each). The primary outcome was the performance error (ΔC = measured minus predicted plasma concentration) during and after TCI. Secondary outcomes included hemodynamic pharmacokinetic-pharmacodynamic (PK-PD) model, anesthetic depth (BIS), cardiac function (LVEF, SV), electrocardiographic PK-PD model (QTc, QTcd), and recovery profiles. While no significant differences in ΔC were observed during TCI, the Marsh model demonstrated significantly lower ΔC at all time points after TCI cessation (p < 0.05). Compared to the Schnider group, the Marsh group also showed higher BIS values, better preserved LVEF and SV, shorter QTc/QTcd intervals, reduced propofol requirements, and shorter recovery times (all p < 0.05). In conclusion, under the conditions of this study, in which propofol TCI was configured using total body weight for the Marsh model and lean body weight for the Schnider model, the Marsh model provided more accurate plasma concentration control, better hemodynamic stability, and improved recovery profiles compared with the Schnider model for anesthetic induction in obese cardiac surgery patients.