The Risk Factors of Prolonged Mechanical Ventilation after Isolated Coronary Artery Bypass Graft Surgery

Failure to wean a patient from mechanical ventilation after cardiac surgery is associatedwith poor outcome.

The present study was performed aimed to investigate the risk factors of prolonged mechanicalventilation (PMV) following isolated coronary artery bypass graft (CABG) surgery.

This retrospective cohort study was performed on 2155 consecutive adult patientsundergoing isolated coronary artery bypass graft surgery (May 2012 to November 2016 at Imam Rezahospital, Mashhad, Iran). The subjects were assessed for duration of weaning from mechanicalventilation, predictive risk factors for prolonged mechanical ventilation and associated outcomesincluding intensive care unit (ICU) and hospital length of stay (LOS), and mortality. Data wereanalyzed by SPSS (version 22). P<0.05 was considered statistically significant.

The median (25 -75 percentile) duration of mechanical ventilation was 360 (225-540)minutes. Also, 51.20%, 45.80% and 2.30% patients were weaned from mechanical ventilation in lessthan 6 hours, 7 to 24 hours, and more than 24 hours, respectively. Cerebral vascular accident was themost common cause of PMV (34.04%). After adjustment for confounder variables, on-pump CABG(P<0.05), duration of surgery (P<0.01), preoperative renal failure (P<0.05) and New York HeartAssociation (NYHA) class 4 were associated with PMV (P <0.05). PMV was associated withincreased length of ICU and hospital stay (P<0.01). There was a higher mortality rates in patients withPMV (P<0.001).

Implications for Practice: 

Most patients are weaned from mechanical ventilation within 24 hoursuneventfully after isolated CABG. Furthermore, on-pump CABG, prolonged surgery, preoperativerenal insufficiency, and NYHA class 4 were independent predictors of prolonged mechanicalventilation. Identifying the risk factors causing PMV can prevent its adverse consequences.