Red blood cell transfusion and ventilator-associated pneumonia: A potential link?

Objective: To determine the relationship between packed red blood cell transfusion practice and the development of ventilator-associated pneumonia (VAP). Design: Secondary analysis of a multicentered, prospective observational study of transfusion practice in intensive care units in the United States. Setting: A total of 284 intensive care units in the United States were studied from August 2000 to April 2001. Patients: Patients without pneumonia at intensive care unit admission and who then required at least 48 hrs of mechanical ventilation were considered at risk for VAP. Measurements and Main Results: VAP was diagnosed based on prospectively defined clinical criteria and represented the primary study end point Late-onset VAP (VAP arising after ≥5 days of mechanical ventilation) represented a secondary end point. Transfusions given during the intensive care unit stay and before the onset of VAP were tracked prospectively. Of 4,892 subjects in the original cohort, 1,518 received mechanical ventilation of ≥48 hrs and did not have preexisting pneumonia. VAP was diagnosed in 311 (20.5%) patients. Multivariate analysis revealed that transfusion independently increased the risk for VAP (odds ratio, 1.89; 95% confidence interval [CI], 1.33-2.68). Other factors increasing the risk for VAP included male sex (odds ratio, 1.54; 95% CI, 1.15-2.07), admission after trauma (odds ratio, 1.68; 95% CI, 1.15-2.47), use of continuous sedation (odds ratio, 1.43; 95% CI, 1.07-1.92), and type of nutritional support (e.g., early enterai nutrition: odds ratio, 2.65; 95% CI, 1.93-3.63; total parenteral nutrition: odds ratio, 3.27; 95% CI, 2.24-4.75). The effect of transfusion on late-onset VAP was more pronounced (odds ratio, 2.16; 95% CI, 1.27-3.66) and demonstrated a positive dose-response relationship (p = .0223 for trend test). Conclusions: Transfusion of packed red blood cells increases the risk of developing VAP. Avoiding the unnecessary use of packed red blood cell transfusions may decrease the occurrence of VAP.