Risk Factors for Prolonged ICU Stay in Patients Following Coronary Artery Bypass Grafting With a Long Duration of Cardiopulmonary Bypass

Background: Risk factors for prolonged stay in the intensive care unit (ICU) in patients following coronary artery bypass grafting (CABG) have been reported in many previous studies. However few have focused on circulatory and respiratory status as immediate postoperative risk factors. Therefore we examined immediate postoperative risk factors for prolonged ICU stay after CABG with a long duration of cardiopulmonary bypass (CPB).

Methods: We studied retrospectively 100 consecutive patients undergoing elective CABG with CPB. Patients were excluded from this study if the duration of aortic cross-clamping was less than 60 min. Patients were divided into three groups according to the duration of the ICU stay. Patients in group A (n = 68) were discharged from the ICU on the next morning after surgery, those in group B (n = 19) stayed for 3 days, and group C (n = 13) stayed for more than 3 days. Perioperative variables were compared among the three groups and we demonstrated risk factors for prolonged (more than 3 days) ICU stay.

Results: There were significant differences in duration of CPB (157 +/- 34 versus 184 +/- 48 minutes, P < 0.05) and aortic cross-clamping (119 +/- 32 versus 141 +/- 40 min) between groups A and B. On the other hand, there were significant differences in age (62.8 +/- 7.8 versus 67.4 +/- 6.2 years), mean pulmonary artery pressure (MPAP) (17 +/- 2 versus 22 +/- 3 mmHg), and Pa(O) (2)/FI: (O) (2) (PF ratio) (409 +/- 94 versus 303 +/- 108 mmHg) on admission to the ICU between groups A and C. There were no significant differences in intraoperative fluid balance and duration of CPB. Multiple logistic regression analysis identified age (>65 years), MPAP (>21 mmHg), and PF ratio (<300 mmHg) as independent risk factors for more than a 3-day ICU stay.

Conclusion: Advanced age, increased MPAP, and decreased PF ratio on admission to the ICU were significant risk factors for a prolonged ICU stay of more than 3 days.