Background/Objectives: General anesthesia is occasionally required for cesarean delivery (CD). Propofol target-controlled infusion (TCI) enables dosing based on pharmacokinetic modeling. During the transition from induction to maintenance, infusion pauses. This simulation study assessed propofol from induction to delivery and the proportion of deliveries estimated during this pause. Methods: Surgical data from women undergoing CD were compiled, and the demographics were entered into a TCI pump using the Schnider model. Effect-site targets (6 and 8 mcg/mL) were simulated for induction, followed by 2.5 mcg/mL for maintenance. Outcomes were estimated propofol dose from induction to delivery and timing of delivery relative to infusion pause. Results: Among 50 women, the estimated mean propofol dose from induction to delivery was 19 ± 22 mg (0.2 ± 0.3 mg/kg) at 6 mcg/mL and 13 ± 17 mg (0.2 ± 0.2 mg/kg) at 8 mcg/mL. Delivery occurred during the infusion pause in 40% and 50% of cases, and it was more often in emergency than elective procedures. Emergency status, but not age or body mass index, predicted delivery during the pause. Conclusions: Standardized TCI with reduced effect-site targets for maintenance resulted in modest propofol administration between induction and delivery. These findings require confirmation in clinical studies, where dosing should be guided by depth-of-anesthesia monitoring.

Background/Objectives: Remifentanil may be useful during general anesthesia for cesarean delivery, although the amount administered before delivery using target-controlled infusion (TCI) at different effect-site targets has not been well quantified. This pharmacokinetic study investigated how much remifentanil would be delivered before birth at different initial effect-site targets. Methods: This retrospective simulation study used demographic data from 50 women undergoing cesarean delivery. Remifentanil TCI (Minto model) was simulated with initial effect-site targets of 1, 2, 4, and 6 ng/mL. One minute after the simulated plasma peak, the target was reduced to 1 ng/mL (t₀). Doses before t₀, duration of the infusion pause, and total dose before delivery were calculated. Simulated dosing patterns were summarized overall and stratified by elective and emergency procedures. Results: Infusion pauses after target reduction lasted 175, 346, and 503 s after initial targets of 2, 4, and 6 ng/mL, respectively. Delivery occurred during these pauses in 16%, 46%, and 72% of cases (19%, 71%, and 90% in emergency cases). Mean remifentanil dose at delivery was 33.7, 43.0, 70.0, and 101.0 μg for initial targets of 1, 2, 4, and 6 ng/mL, respectively. Following target reduction, the additional remifentanil administered before delivery decreased from a mean of 17.0 μg with an initial effect-site target of 1 ng/mL to 0.9 μg with an initial target of 6 ng/mL. Conclusions: This simulation demonstrated that only modest additional doses of remifentanil would be delivered to the mother between induction and delivery during target-controlled infusion for cesarean delivery, with the exact amount depending on the initial effect-site target concentration.