RESUMEN
Beta-lactam dosing is challenging in critically ill patients with slow extended daily dialysis (SLEDD). This prospective observational study aimed to investigate meropenem and piperacillin concentrations and half-lives during SLEDD and in SLEDD-free intervals. Critically ill patients with SLEDD-therapy and meropenem or piperacillin therapy were included. Breakpoints of target attainment were defined as 2 and 20.8 mg/L for meropenem and piperacillin, respectively. Daily TDM was performed and therapies were adapted based on the measured concentrations. Elimination rate constants were determined by using nonlinear regression analysis. Seventeen patients were included (48 SLEDD intervals; median SLEDD-duration: 7.25 h). The median antibiotic trough concentrations and half-lives were significantly (p < 0.001) lower during and after the SLEDD-therapy compared to SLEDD-free intervals (median meropenem: 22.3 (IQR: 12.8, 25.6) vs. 28.3 mg/L (IQR: 16.9, 37.4); median piperacillin: 55.8 (IQR: 45.1, 84.9) vs. 130 mg/L (IQR: 91.5, 154.5); relative change: -48.0% each, IQR meropenem: -33.3, -58.5%; IQR piperacillin: -36.3, -52.1%). However, none of the measured trough concentrations were subtherapeutic during SLEDD. SLEDD leads to a reduction in meropenem and piperacillin concentrations of approximately 50% independently of the initial concentration. If the concentration is twice as high as the breakpoint of target attainment before SLEDD-therapy, subtherapeutic levels can be avoided.