BACKGROUND: Challenging separation from cardiopulmonary bypass (CPB) has been associated with multiple medical adversities, while its incidence, associated factors, and prognosis among cardiac surgery populations are substantially understudied.

METHODS: Adult cardiac surgical patients in two medical centers were retrospectively analyzed. Separation from CPB was stratified as easy, difficult, or complex, based on the use of pharmacologic assistance agents and mechanical supports. The various in-hospital adverse outcomes (e.g., mortality, common complications) were assessed.

RESULTS: The incidence of difficult and complex separation from CPB was 21.9% (1159 cases, 95% CI 20.8% to 23.1%), and 6.1% (320 cases, 95% CI 5.4% to 6.7%), respectively. Aged, the presence of pulmonary hypertension or unstable angina, decreased ejection fraction, and underwent emergency surgery were associated with challenging separation from CPB. Patients who experienced challenging separation from CPB had an elevated risk of adverse outcomes, including in-hospital mortality (complex: odds ratio [OR] 2.85), composite infection events (difficult: OR=1.82; complex: OR=1.88), major adverse cardiac events (difficult: OR=1.40; complex: OR=1.57), pulmonary complications (difficult: OR=1.31; complex: OR=1.20), acute kidney injury (difficult: OR=1.75; complex: OR=2.64), and prolonged postoperative hospital stays.

CONCLUSIONS: We depicted the incidence of challenging separation from CPB among cardiac surgery population. Additionally, results of influential factors and various adverse outcome analyses emphasize the potential of interventions aimed at preventing difficult or complex separation from CPB and reducing associated adverse outcomes.