Abstract: Objective To investigate whether the routine regimen of β-lactams is appropriate for patients with septic shock receiving continuous renal replacement therapy (CRRT). Methods Septic shock patients treated with CRRT and receiving either imipene (IPM), piperacillin- tazobactam (TZP) or cefepime (FEP) were enrolled in this study. Serum concentrations of β- lactams were measured by high- performance liquid chromatography for samples taken before and after use of the antibiotics for 0.5, 1, 2, 4, 6 or 12 hours. Blood samples were then separated into early phase (samples taken＜48 hours after the first dose) and late phase (＞48 hours). Results Twenty-four patients (IPM, n=9; TZP, n=8; FEP, n=7) were enrolled in this study. Fortyfive blood samples (IPM, n=15; TZP, n=16; FEP, n=14) were collected. Serum concentrations more than 4 times above the minimal inhibitory concentration (MIC) for pseudomonas aeruginosa were found in 47% of the patients treated with IPM, in 75% with TZP, and in 0% with FEP. Conclusion In septic shock patients receiving CRRT, serum β-lactams concentrations for killing pseudomonas aeruginosa were insufficient in some cases. Higher doses or extended infusions should be considered for required serum concentrations.

Key words: Septic shock, Continuous renal replacement therapy, β-lactams