The Impact of Ventilator-Associated Events in Critically Ill Subjects With Prolonged Mechanical Ventilation

The Centers for Disease Control and Prevention recently released a surveillance definition for respiratory complications in ventilated patients, ventilator-associated events (VAEs), to replace ventilator-associated pneumonia (VAP). VAEs consist of ventilator-associated conditions (VAC), infection-related ventilator-associated complications (IVAC), and possible VAP. A duration of mechanical ventilation of at least 4 d is required to diagnose VAE. However, the observed duration of mechanical ventilation was < 4 d in many previous studies. We evaluated the impact of VAEs on clinical outcomes in critically ill subjects who required mechanical ventilation for ≥ 4 d.

This single-center retrospective cohort study was conducted in the general ICU of an academic hospital. We included 407 adult subjects who were admitted to the ICU and required mechanical ventilation for at least 4 d. VAC and IVAC were identified from the electronic medical records. VAP was defined according to the Centers for Disease Control and Prevention 2008 criteria and was identified from the surveillance data of the infection control team of our hospital. Clinical outcomes were studied in the VAC, IVAC, and VAP groups. Possible VAP was not investigated.

Higher mortality was seen in VAC and IVAC subjects, but not in VAP subjects, compared with those without VAEs and VAP. By multivariable hazard analysis for hospital mortality, IVAC was independently associated with hospital mortality (hazard ratio 2.42, 95% CI 1.39-4.20, P = .002). VAC also tended to show a similar association with hospital mortality (hazard ratio 1.45, 95% CI 0.97-2.18, P = .07). On the other hand, VAP did not increase a hazard of hospital death (hazard ratio 1.08, 95% CI 0.44-2.66, P = .87).

We found that a VAE was related to hospital mortality in critically ill subjects with prolonged mechanical ventilation, and that VAP was not.