propofol-target-controlled-infusion-performance-of-the-schnider-model-in-the-clinical-setting-for-major-surgical-procedures

Abstract

Background: Limited data are available about the difference in propofol plasma levels estimated by target controlled infusion models (TCI) and measured plasma levels during prolonged operations. We hypothesized the difference to be greater at the end of surgery than at the beginning.Methods: For this prospective observational study, adult patients were enrolled (elective surgery, estimated operating time of ≥ 3 hours, eligible to receive propofol using TCI (Schnider model)). Blood was sampled in steady state after anesthesia induction (propofol dosed to achieve BIS values of 40-60; T 1 ) and at the end of the procedure (T 2 ). Fluid balance was recorded. Bias and limits of agreement of actual plasma levels (C blood ) to TCI values (C TCI ) were calculated, hemodynamics assessed, and performance error (PE) measured (PE(%) = ((C blood -C TCI )/C TCI )*100) and assessed for correlations.Results: Thirty patients were included. Mean duration of procedure was 250 min (± 136.7), fluid balance 2066 ml (± 1017), and all patients were hemodynamically stable. Mean C TCI was 2.0 µ/ml (± 0.3) and 1.8 µ/ml