Randomized, controlled trial on tracheal colonization of ventilated infants: Can gravity prevent ventilator-associated pneumonia?

OBJECTIVE. The goal was to test the hypothesis that intubated infants positioned on their sides would be less likely to contract bacterial colonization in their tracheae, compared with those positioned supine. METHODS. We conducted a prospective, randomized, controlled trial with 60 intubated infants; 30 infants were positioned supine (supine group), and 30 infants were maintained in the lateral position (lateral group). Tracheal aspirates were cultured and bacterial colony counts were recorded after 48 hours and after 5 days of mechanical ventilation. RESULTS. After 2 days, the numbers of positive tracheal cultures in the supine group (67%) and in the lateral group (47%) showed no statistical difference. After 5 days of mechanical ventilation, tracheal cultures differed significantly between groups. Cultures were positive for 26 infants (87%) in the supine group and 9 infants (30%) in the lateral group. Compared with the lateral group, more infants in the supine group experienced increased colony counts or had new organisms in their tracheal aspirates over time (21 vs 8 infants). The most common organisms isolated from tracheal aspirates in both groups were Gram-negative rods. CONCLUSIONS. Respiratory contamination is very common among ventilated infants. Therefore, judicious use of mechanical ventilation cannot be overemphasized. Gravitational force can ameliorate the onset of respiratory colonization. The mechanism and clinical applicability of such observations need to be explored further.