Objective: To determine whether continuous subglottic aspiration prevents nosocomial pneumonia in mechanically ventilated patients.
Design: A randomized, controlled, blinded study.
Setting: Medical-surgical intensive care unit.
Patients: 190 patients who were admitted to the intensive care unit during a 33-month period and whose condition suggested the need for prolonged intubation (>3 days).
Intervention: 76 patients were randomly allocated to receive continuous aspiration of subglottic secretions, and 77 control patients were allocated to receive usual care.
Measurements: The numbers of cases of ventilator-associated pneumonia, ventilated days, days in intensive care unit, and deaths were recorded. The amount of subglottic secretions aspirated daily and surveillance cultures in the subglottic secretions were also obtained periodically. Etiologic diagnosis was based on the quantitative culture of secretions obtained by protected specimen brush or bronchoalveolar lavage.
Results: The incidence rate of ventilator-associated pneumonia was 19.9 episodes/1000 ventilator days in the patients receiving continuous aspiration of subglottic secretions and 39.6 episodes/1000 ventilator days in the control patients (relative risk, 1.98; 95% CI, 1.03 to 3.82). This difference was due to a significant (P < 0.03) reduction in the number of gram-positive cocci and Haemophilus influenzae organisms in the patients receiving continuous aspiration. However, no differences were observed in the number of Pseudomonas aeruginosa or Enterobacteriaceae organisms. Episodes of ventilator-associated pneumonia occurred later in patients receiving continuous aspiration (12.0 ± 7.1 days) than in the control patients (5.9 ± 2.1 days) (P = 0.003). The same microorganisms isolated from protected specimen brush or bronchoalveolar lavage cultures in patients with ventilator-associated pneumonia were previously isolated from cultures of subglottic secretions in 85% of cases. No significant differences in outcome were found.
Conclusions: The incidence of nosocomial pneumonia in mechanically ventilated patients can be significantly reduced by using a simple method that decreases the chronic microaspirations through the cuff of endotracheal tubes.