What is the best position for preventing ventilator-associated pneumonia?

Preventing aspiration in mechanically ventilated patients continues to be a key component in the battle toward reducing the incidence of ventilator-associated pneumonia (VAP). These aspiration events (especially micro-aspirations) are a major VAP risk factor and thus have become a target of the quality-improvement movement.1 VAP bundles have been introduced into intensive care units worldwide, and contain modalities designed to minimize aspiration risk. One universal intervention involves placing mechanically ventilated patients into the semi-recumbent position (30–45°) rather than the fully supine position.2-4 Surprisingly, the data to support semi-recumbent positioning are relatively sparse and are based on 3 small initial studies, the largest of which was published in The Lancet in 1999 and involved 85 patients.5-7 That study compared 39 patients in the 45° semi-recumbent position to 47 patients in the fully supine position, and the incidence of VAP was markedly lower in the semi-recumbent group (8% vs 34%, P .003).5 Following that landmark study, the semi-recumbent positioning became integrated into practice guidelines, but with lower head-of-bed elevation ( 30°) because of the risk of decubitus ulcers at higher elevations.8 Since the widespread adoption of semi-recumbent positioning, there have been virtually no further studies specifically designed to examine patient positioning alone as a risk factor in the development of VAP. However, the semi-recumbent position remains problematic, and although it is superior to the supine position, it is far from ideal in the prevention of aspiration.3-4 In this issue of the Journal, Mauri et al report their feasibility study of the novel lateral-horizontal patient position, which they propose is safe, compared to semi-recumbent positioning, and theoretically may have several advantages.9 Mauri et al observed 10 patients in the semi-recumbent position for 64 hours, and 10 patients in the lateral-horizontal position for up to 24 hours.9 There were no differences in adverse events, sedation scores, sedation medication need, or hemodynamic changes between the 2 positions. This implies that the lateral-horizontal position is safe; however, it is important to note that the potential to detect an adverse event was higher in the semi-recumbent group, as they were observed longer than the lateral-horizontal group. Thus, it is difficult to determine if the incidence of adverse events would be equivalent if the 2 groups were studied for the same time periods. This limited preliminary study needs to be replicated with a larger patient group observed for equal time frames to definitively establish the safety of the lateral-horizontal position.