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)
Adult patients treated at CHU Liège who are scheduled for elective abdominal surgery under general anesthesia and for whom an ultrasound-guided transversus abdominis plane (TAP) block with levobupivacaine is planned as part of routine perioperative analgesic care. The study population consists of clinically stable surgical patients able to provide informed consent and undergo serial perioperative blood sampling for pharmacokinetic analysis.
Cohort
Prospective
Ultrasound-Guided Transversus Abdominis Plane Block with Levobupivacaine
Procedure/SurgeryUltrasound-guided transversus abdominis plane (TAP) block performed as part of routine perioperative analgesia after induction of general anesthesia for elective abdominal surgery. Levobupivacaine 0.375% is injected into the transversus abdominis fascial plane under real-time ultrasound visualization, using a total volume of 40 mL (typically bilateral administration, adjusted to surgical indication), with a maximum total dose of 150 mg. The block is performed by an experienced anesthesiologist according to institutional standard practice.
Maximum Plasma Levobupivacaine Concentration (Cmax)
Maximum observed plasma concentration (Cmax, µg/mL) of levobupivacaine after TAP block, determined from serial plasma samples collected during the first 180 minutes after completion of the block.
Time to Maximum Plasma Levobupivacaine Concentration (Tmax)
Time to maximum observed plasma concentration (Tmax, minutes) of levobupivacaine after TAP block, determined from serial plasma samples collected during the first 180 minutes after completion of the block.
Area Under the Plasma Concentration-Time Curve From 0 to 180 Minutes (AUC0-180) of Levobupivacaine
Area under the plasma concentration-time curve (AUC0-180, µg·min/mL) of levobupivacaine following TAP block, calculated from serial plasma concentration measurements obtained during the first 180 minutes after completion of the block.
Plasma Levobupivacaine Concentration at Each Sampling Time Point
Measured plasma concentration (µg/mL) of levobupivacaine at predefined sampling time points after TAP block.
Interindividual Variability of Maximum Plasma Levobupivacaine Concentration (Cmax)
Interindividual variability of maximum plasma levobupivacaine concentration (Cmax), assessed using descriptive dispersion measures including standard deviation and coefficient of variation.
Association Between Area Under the Plasma Concentration-Time Curve (AUC0-180) and Clinical Factors
Association between levobupivacaine AUC0-180 (µg·min/mL) and predefined clinical factors including age, sex, body mass index (BMI), and type of surgery.
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