Respiratory tract infections after cardiac surgery: impact on hospital morbidity and mortality

Aim. Nosocomial pneumonia (NP) and tracheobronchitis after cardiac surgery are associated with worse outcomes. The aim of this study was to identify risk factors associated with NP and tracheobronchitis after cardiac surgery and to determine the impact of these infections on hospital morbidity and mortality. Methods. We evaluated 1 600 adult patients undergoing cardiac surgery under standard cardiopulmonary bypass. Data were collected prospectively. All NP and tracheobronchitis episodes were confirmed by a semi-quantitative culture of endotracheal aspirate. Logistic regression analysis was done to identify risk factors for respiratory tract: infection and mortality. Results. The rate of NP was 1.2% (15.6 episodes per 1 000 days of mechanical ventilation) and that of tracheobronchitis was 1.6% (21 episodes per 1 000 days of mechanical ventilation). Significant independent risk factors for respiratory tract infection (pneumonia or tracheobronchitis) were: left ventricular ejection fraction <30% (P=0.001), chronic renal failure (P<0.0001) and urgent surgery (P<0.0001). Patients with NP had significantly higher mortality (42% versus 0.9%, P<0.0001) than patients without respiratory tract infection. The Median hospital length of stay was significantly longer in patients with pneumonia (42 days) and tracheobronchitis (28 days) than in patients without any respiratory tract infection (11 days, P<0.0001.). Conclusion. NP after cardiac surgery is associated with severe outcomes. Independent risk markers for respiratory tract infection were left ventricular ejection fraction <30%, chronic renal failure and urgent surgery.