Antimicrobial Under-Dosing Common in CVVHD

DENVER—Antimicrobial dosing may not meet guideline recommendations in a significant number of patients receiving continuous venovenous hemodialysis (CVVHD), new findings presented at the 53rd Interscience Conference on Antimicrobial Agents and Chemotherapy suggest.

“We found that 22% of patients didn't have the right dose for the entire time they were on continuous venovenous hemodialysis, which means they are not getting enough antibiotic and it means we are not controlling the infection,” said investigator Marianna Fedorenko, PharmD, an infectious disease pharmacy resident at Barnes-Jewish Hospital in St. Louis, MO. “I think this is something that nephrologists should be looking at as part of their assessment of the patients.”

Dr. Fedorenko and her colleagues at Cleveland Clinic conducted a retrospective study in which they evaluated 42 patients receiving CVVHD and intravenous antimicrobial therapy during a two-month period. Subjects had a mean age of 58.4 years and 47.6% were male. The objective was to analyze the number of study days the antimicrobial doses were in accord with institutional guidelines. The most frequently prescribed antimicrobials were piperacillin/tazobactam and meropenem.

Antimicrobial therapy dosing met guideline recommendations for only 163 (78%) of the 209 study days, and all non-concordant doses were below guideline recommendations. “We think this is a problem across the U.S. A lot of these patients are under-dosed,” said Dr. Fedorenko, who noted that CVVHD alters antimicrobial pharmacokinetics.

Based on survival analyses, the median time to recommended dose was 20 hours after CVVHD initiation. In cases where antimicrobial therapies were initiated when patients were already on CVVHD, 74% of the initial doses met guideline criteria. Additionally, the study showed that pharmacist recommendations were associated with increased dosing compliance (93.9% vs. 73.1%). During transition from CVVHD to thrice-weekly hemodialysis (HD), only 62% of antimicrobial therapies doses were decreased by the first day of thrice-weekly HD.

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