This prospective single-center observational pharmacokinetic study will evaluate plasma levobupivacaine concentrations after ultrasound-guided transversus abdominis plane (TAP) block in adult patients undergoing elective abdominal surgery under general anesthesia at CHU Liège. Participants receiving TAP block as part of standard clinical care (levobupivacaine 0.375%, total volume 40 mL, maximum dose 150 mg) will undergo serial blood sampling at 3, 7, 15, 30, 60, 120, and 180 minutes after block completion. Plasma levobupivacaine concentrations will be measured using validated LC-MS/MS methods. The primary objectives are to estimate maximum plasma concentration (Cmax) and time to maximum concentration (Tmax). Secondary objectives include characterization of the concentration-time profile, AUC0-180, interindividual variability, and exploratory associations with clinical factors (age, sex, BMI, type of surgery). The study also aims to inform a pragmatic safety window for subsequent intravenous lidocaine infusion used in multimodal analgesia protocols. Approximately 26 participants will be enrolled. No modification of routine anesthesia or analgesic care is required apart from study-related blood sampling.
Age ≥18 years
Scheduled elective abdominal surgery under general anesthesia
Planned ultrasound-guided TAP block as part of standard perioperative analgesic care
Able to understand and speak French sufficiently to understand the study information and consent form
Refusal or inability to provide informed consent
Known allergy or hypersensitivity to amide local anesthetics
Severe hepatic impairment
Renal impairment (estimated glomerular filtration rate <50 mL/min/1.73 m²)