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QUESTION: Which interventions prevent ventilator associated pneumonia (VAP) in critically ill patients?
English language studies were identified by searching Medline (1966–2001) and the Cochrane Library, and by reviewing bibliographies of retrieved articles.
Studies were selected if they were randomised controlled trials (RCTs) or observational cohort controlled trials.
Data were extracted on study design, intervention, and outcomes.
34 studies met the selection criteria. Meta-analysis was not done because of study variations in the diagnostic criteria for pneumonia. Results are summarised in the table.
Semirecumbent positioning, stress ulcer prophylaxis (sucralfate rather than H2 antagonists), aspiration of subglottic secretions, selective digestive tract decontamination, and oscillating beds reduce ventilator associated pneumonia (VAP) in select critically ill patients. No evidence currently supports specific methods of enteral feeding or increased frequency of ventilator circuitry changes for prevention of VAP.
VAP is a common condition among critically ill patients and a burden to healthcare systems. Although the incidence of VAP is difficult to determine because of diagnostic variability, research shows a 20–30% mortality rate,1 longer ICU and hospital stays, and higher hospital costs for patients with VAP.2
The systematic review by Collard et al provides a thorough analysis of the evidence to date, highlighting the considerable gaps in our knowledge. In selecting studies for inclusion, the authors noted the lack of standardised diagnostic criteria, which prevented pooling of individual study results in a meta-analysis. Diagnostic criteria for VAP may include fever, leukocytosis, purulent secretions, and changes on chest radiography and microbiology. Limitations of existing studies included small sample sizes, lack of power, and equivocal and conflicting findings.
Although semirecumbent positioning of all eligible patients appears easy, inexpensive, and relatively uncontroversial, evidence on practices such as oscillation beds and selective digestive decontamination is equivocal. Collard et al correctly attributed these conflicting findings to differences in inclusion criteria, outcome measures, and analyses used in individual studies. They also caution practitioners about the use of selective digestive tract decontamination because of uncertainties about effects of such treatment on antibiotic resistance, although no additional evidence to support this was included in the review.
Although cost may be a barrier for many of these practices, it is important to educate clinicians to take measures to prevent and recognise symptoms, and diagnose VAP. Collard et al also noted that to date, no RCT has evaluated the effectiveness of combined preventative practices. Given the high mortality rate associated with VAP, this research should be a priority.
Sources of funding: Department of Veterans Affairs and National Institutes of Health.
For correspondence: Dr H R Collard, Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Health Sciences Center, Denver, CO, USA.
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