Predictors and Outcomes of Prolonged Ventilation after Coronary Artery Bypass Graft Surgery

Abstract

This study investigated and compared the risk factors and outcomes of patients undergoing coronary artery bypass graft surgery with and without the occurrence of prolonged mechanical ventilation. Data in a cardiac surgery database were examined retrospectively. Data selected included any isolated coronary artery bypass graft surgery performed by the surgical group from August 2005 to June 2009. The resulting cohort included a total of 2933 patients which was comprised of 116 patients with a ventilation time of greater than 72 hours (prolonged ventilation) and 2817 patients with a ventilation time of 72 hours or less (no prolonged ventilation). Patients with a prolonged ventilation time were matched (1:3 ratio) to patients not requiring a prolonged ventilation time by year of surgery resulting in our study cohort of 464 patients. To generate the unadjusted risks of each factor, χ2 and t test analysis were performed. Logistic regression analysis was then used to investigate the adjusted risk between cases and controls and each of the significant variables. χ2 and t tests were conducted comparing cases and controls with the outcome variables. Patients undergoing coronary artery bypass graft that experienced a prolonged ventilation time (cases) were more likely female, had a New York Hospital Association functional class of III or IV, and had a longer perfusion time. There was no significant difference between cases and controls with diabetes, chronic obstructive pulmonary disease, left ventricular ejection fraction, or body mass index while controlling for all significant risk factors. Careful patient selection and preparation during preoperative evaluation may help identify patients at risk for prolonged mechanical ventilation and thus help prevent the added morbidity and mortality associated with it.