To determine the incidence and the associated intraoperative factors that contribute to difficult weaning from cardiopulmonary bypass (CPB) among coronary artery bypass graft (CABG) patients with preserved left ventricular ejection fraction (LVEF).

This study was a prospective observational cohort study conducted at a specialty center from September 1, 2019, to May 15, 2020. It included adult patients diagnosed with coronary artery disease (CAD) admitted for elective CABG under the CABG Z-Benefit Package, with an LVEF of greater than 50%. After institutional review board approval, data on consecutive patients scheduled for elective, isolated CABG and meeting the inclusion criteria were prospectively collected and analyzed. Descriptive or qualitative statistics was used to summarize the demographic and clinical characteristics of the patients.

Data from 52 patients who met the inclusion criteria were included in the analysis, with 17.3% (n = 9/52) meeting the criteria for difficult weaning from CPB. Of these nine patients, nine (100%) required use of more than one inotrope and/or vasopressor, and two of the nine (22.22%) needed to return to CPB after coming off. Of those patients with nondifficult weaning from CPB, 74.44% (n = 32/43) used a single inotrope, and 42.26% (n = 11/43) successfully separated from CPB without any need for pharmacological support. Among the various parameters assessed, logistic regression analysis showed that every unit increase in base deficit after release of aortic cross-clamp increased the odds of having difficult separation from CPB by 40.21%. Patients who received nicardipine were also 7.8 times more likely to have difficult separation from CPB.

In this study of patients with preserved left ventricular function undergoing CABG surgery, we identified two intraoperative variables associated with difficult weaning from CPB: (1) base deficit at release of aortic cross-clamp and (2) the use of nicardipine infusion.