Early piperacillin exposure during continuous infusion in critically ill patients: the impact of renal and liver dysfunctions.

Objective: To assess early piperacillin exposure in critically ill patients receiving continuous infusion piperacillin-tazobactam, identify clinical determinants of underexposure and overexposure, and evaluate piperacillin concentrations across organ dysfunction phenotypes. Design: Retrospective, single-center observational study. Setting: A 20-bed medical-surgical intensive care unit of a university hospital. Patients: All consecutive adult critically ill patients receiving continuous-infusion piperacillin-tazobactam with at least one total plasma piperacillin concentration measurement. Interventions: None. Measurements and Main Results: Observed plasma piperacillin concentrations were measured at predefined time points (day 1, day 3 and day 7). Target attainment was defined as total plasma concentrations of 80-160 mg/L, corresponding to 4-8 times the minimum inhibitory concentration of Conclusions: Only one-third of critically ill patients achieved target piperacillin exposure at initial therapeutic drug monitoring during continuous infusion. Early deviations from target concentrations were frequent and primarily determined by renal dysfunction despite routine dose adjustment. These findings support early individualized dosing strategies integrating organ function assessment and therapeutic drug monitoring to optimize piperacillin exposure.