Prolonged Mechanical Ventilation as a Predictor of Mortality After Cardiac Surgery

Abstract

Background: Mortality among the small percentage of cardiac surgery patients receiving prolonged mechanical ventilation is high, but this issue appears to be inadequately addressed in guidelines.

Methods: This study is a retrospective analysis of prospective, multi-center, and observational study in Spain including all adults undergoing cardiac surgery in 3 Andalusian hospitals between June 2008 and December 2012.

Results: The study included 3,588 adults with mean ± SD age of 63.5 ± 12.8 y and with median (interquartile range) EuroSCORE of 5 (3-7) points. Prolonged mechanical ventilation (> 24 h) was required by 415 subjects (11.6%), with ICU mortality of 44.3% (184 subjects), and was not required by 3,173 subjects (88.4%), with ICU mortality of 3.1% (99 subjects, P < .001). Prolonged mechanical ventilation was associated with more complications and was required by 4.5% of subjects with a EuroSCORE <5, 11.2% with a score of 5-7, 27.2% with a score of 8-10, and 32.2% with a score > 10. In the multivariable analysis, ICU mortality was associated with illness severity, duration of bypass surgery, surgery type, and prolonged mechanical ventilation (odds ratio 15.19, 95% CI 11.56-22.09). The main cause of death was multiple organ failure and sepsis in subjects who required prolonged mechanical ventilation (50.3%) and cardiogenic shock in those who did not (59.2%).

Conclusion: Prolonged postoperative mechanical ventilation was required by 10-20% of cardiac surgery subjects, who constitute a specific group that represents most of the postoperative mortality, which is associated with multiple organ failure and sepsis.

Keywords: cardiac surgery; mechanical ventilation; mortality; severity.