Ventilator-associated events after cardiac surgery: evidence from 1,709 patients

Abstract

Background: Ventilator-associated event (VAE) is a new surveillance for nosocomial infections in mechanically ventilated patients. To date, little is known about VAEs after cardiac surgeries. The present study firstly focused on patients who have undergone heart operations, intending to draw a comprehensive description of VAEs.

Methods: Postoperative patients from September 2012 to December 2015 were monitored for VAEs. By reviewing electronic medical records and preserved files retrospectively, clinical data were further analyzed.

Results: A total of 1,709 adult patients were enrolled, of which 166 episodes met the criteria for VAE. The mean incidence rate reached up to 9.7% and 49.9 per 1,000 mechanical ventilation days. By using both univariate analysis and multiple logistic regression analysis, chronic obstructive pulmonary disease (COPD), left ventricle ejection fraction (LVEF) <30%, cardiopulmonary bypass time, aortic clamping time, mechanical ventilation time, reintubation, dosage of blood products and acute kidney injury (AKI) were found to be risk factors for VAEs. Compared with non-VAE group, VAEs were closely related to higher mortality, longer intensive care unit stay time and hospitalization time. In addition, 91 strains of pathogens were isolated from endotracheal aspirates of 81 patients with VAE, of which Pseudomonas aeruginosa was the most common pathogenic microorganism (30 isolates, 37.0%), followed by Acinetobacter baumannii (27 isolates, 33.3%) and other five types.

Conclusions: VAE algorithm is a valid and reliable surveillance for possible infections caused by mechanical ventilation, which could easily occur in patients after cardiac surgery and is associated with poor prognosis. The risks and pathogens that we have investigated will provide potential preventive strategies.

Keywords: Ventilator-associated events (VAEs); cardiac surgery; etiology; prevalence; prognosis; risk factors.

Figure 1

Flow diagram of VAE surveillance. VAE, ventilator-associated event; FiO₂, fraction of inspired oxygen; PEEP, positive end expiratory pressure; CFU, colony forming unit.