ABSTRACT

The objective of this study was to identify predictors of prolonged mechanical ventilation for those who had coronary artery bypass grafting (CABG) surgery, by evaluating their perioperative data.

Five hundred consecutive patients who had CABG surgery between December 2004 and December 2007 were retrospectively evaluated after the approval of Baskent University Clinical Studies Committee. Patients requiring mechanical ventilation for ≥24 hours (n=22) were included in Group I and those requiring ventilation for < 24 hours (n=463) were included in Group II.

Subjects’ perioperative findings as a predictor for prolonged mechanical ventilation were analyzed by univariate and multivariate regression analysis. The presence of chronic renal failure and cerebrovascular accident (CVA) were higher in Group I when compared to Group II (p<0.01). It was also noted that patients in Group I who needed more than twenty-four hours of postoperative mechanical ventilation received higher rates of emergency surgery than patients in Group II. Preoperative blood urea nitrogen, creatinine, aspartate aminotransferase levels were higher, albumin and sodium levels were lower in Group I when compared to Group II (p<0.01, p<0.01, p=0.02, p=0.01, and p<0.01 respectively). Anesthesia, surgery and CPB durations were significantly longer for Group I compared to Group II (p<0.01 for all). Those who needed more than twenty-four hours of mechanical ventilation in Group I had significantly lower rectal temperatures and O2 saturation (p=0.02). The need for intraoperative cardiopulmonary resuscitation, the use of intra-aortic balloon pump, and the need for vasopressors and ultrafiltration were higher in Group I when compared to Group II (p<0.01, p<0.01,p=0.02 and p=0.02 respectively). The need for reexploration was higher in Group I (p<0.01). Also, Group I had higher levels of opioid, sedative and muscle relaxant usage till postoperative first extubation (p=0.02, p=0.01, and p=0.01 respectively). Group I had significantly higher requirements of postoperative fresh frozen plasma (FFP) and whole blood (p<0.01 and p=0.03 respectively). Presence of postoperative systemic complications (Group I: 35%, Group II: 5.2%, p<0.01) along with intraoperative and postoperative mortality rates within forty-eight hours (Group I: 22.7%, Group II: %2.7%, p<0.01), were found to be higher in the group that required mechanical ventilation longer than twenty-four hours.

In conclusion, by employing multivariate regression analysis preoperative CVA presence, CPB duration, the decreased levels of intraoperative O2 saturation, post CABG usage of FFP plasma and sedatives were identified as statistically significant predictors of prolonged mechanical ventilation.

Keywords: Coronary artery bypass grafting surgery, prolonged mechanical ventilation