Causes of Prolonged Mechanical Ventilation After Coronary Artery Bypass Grafting Surgery

Background- Coronary artery bypass grafting surgery (CABG) is a commonly performed procedure. More than 10,000 CABG surgery procedures are performed in Iran annually. Prolonged mechanical ventilation following CABG surgery is uncommon. Economic factors have led to a trend for early tracheal extubation after CABG. Fast-track extubation is variously defined but most agree that it refers to extubation within 8 hours. Methods-A descriptive observational study was conducted on 196 patients undergoing CABG surgery. Following surgery, standard weaning protocol was implemented. Patients who failed to be extubated within 8 hrs were evaluated. Results- Four patients (2.04%) died within 3 to 12 days. After undergoing surgery, the minimum duration of mechanical ventilation was 2 hrs, up to a maximum duration of 19 days. 94.3% of the patients were extubated within 24 hrs, with a mean duration of 9.54 hrs. 5.7% of the patients were still intubated after 24h. The most common cause of delayed extubation was physician trend (n=27, 13.8% of patients). Reduced ejection fraction, EKG changes, elderly age, prolonged CPB, difficult intubation were reasons for this trend. The second most common cause was excessive postoperative bleeding, which occurred in 13.3% of the patients. Four percent of the patients were returned to the operating room for re-exploration. Cardiovascular instability (11.7%), metabolic acidosis (9.7%), prolonged recovery (4.7%), neurologic problems (2%), poor FVC (4.6%), hypoxemia (1.5%), and acute respiratory distress syndrome (ARDS) (0.5%) were other reasons. Conclusion- The incidence of prolonged mechanical ventilation for more than 24h was similar to that of the STS database.8 We found the most common cause of delayed extubation to bephysician trend. We recommend changing our strategy in these patients. Excessive postoperative bleeding incidence in our study was slightly higher than that in other studies. We found the proportion of patients with failure to extubate due to various reasons would vary from institution to institution, based on differences in patient population and management strategies(Iranian Heart Journal 2008; 9 (1):47 -54).