STANFORD, CALIF—Ventilator-associated pneumonia (VAP) can prolong the length of ICU stay and increase the risk of death. However, a recent observational study found that treating VAP with antipseudomonal penicillins and ß-lactamase inhibitors may lower in-hospital mortality.[1]

The study included 154 patients with suspected VAP who were admitted to the ICUs of two California medical centers. All patients had been mechanically ventilated for more than 48 hours. Because bronchoscopy and bronchoalveolar lavage were performed in only five cases, most patients were treated empirically—as is common practice in most ICUs.

“Making a definitive diagnosis of VAP is a challenging yet common clinical problem,” said Robert A. Fowler, MD, the study’s primary author. “Definitive diagnosis generally involves a direct pulmonary sampling procedure in order to isolate potentially causative organisms.” Yet, invasive sampling techniques are not often performed.

Part of the problem, said Dr. Fowler, now an Assistant Professor of Medicine at the University of Toronto, is that the results obtained with these procedures are often not worth the risks. “When patients are already receiving antibiotic therapy, the diagnostic yield of subsequent sampling procedures drops off considerably.” In the California study, more than half of the patients had received antibiotics during the 10 days preceding suspicion of VAP.

Once VAP was suspected, 72 patients were given one antibiotic, 47 received two agents, and 35 were treated with three or more drugs. Piperacillin-tazobactam was used in 96 patients. Fluoroquinolones, vancomycin, cephalosporins, and aminoglycosides were also commonly used.

When culture results (predominantly, from pulmonary aspirates) became available, they showed that 142 patients had been given an appropriate empiric antibiotic. The organisms encountered most often were gram-negative bacilli and Staphylococcus aureus.

Fifty-three patients died. Patients whose initial treatment included an antipseudomonal penicillin plus a ß-lactamase inhibitor had lower in-hospital mortality than did the patients given any other regimen.

“Appropriate treatment includes a number of components,” said Dr. Fowler. “Timing is important. Early appropriate therapy has been shown to improve outcomes for patients with VAP.” He added that physicians should be kept informed of pathogens and antibiotic sensitivity patterns in their ICUs.

After therapy is initiated, Dr. Fowler cautioned, it should be reassessed according to patient response and diagnostic test results. “A focused and limited course of therapy may be optimal in preventing antibiotic overuse and potential emergence of resistance,” he said.

Dr. Fowler concluded that more research on VAP is essential—including trials comparing invasive diagnostic sampling with empiric treatment to determine if bronchoscopy affects outcomes. “Implementation and appraisal of clinical guidelines that combine best evidence for prevention, diagnosis, and treatment is a practical area requiring further research.”

—Gale Jurasek

Reference
1. Fowler RA, Flavin KE, Barr J, et al. Variability in antibiotic prescribing patterns and outcomes in patients with clinically suspected ventilator-associated pneumonia. Chest. 2003;123:835-844.

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