Highlights
– A physiologic PK–PD model that includes CO2 kinetics and a ventilatory controller produced a fentanyl potency (C50) estimate for 50% ventilatory depression of 2.3 ± 0.5 ng/mL — roughly one-third of the potency estimated by simpler models.
– Modeling ventilation and end-tidal CO2 (ETCO2) simultaneously under closed-loop conditions yields parameter estimates that may be more pharmacologically plausible and clinically relevant than separate empirical models.
