Purpose: Intensive care unit-acquired weakness (ICUAW) affects patient prognosis after cardiopulmonary bypass (CPB) surgery, but its risk factors remain unclear. We investigated these risk factors and developed a nomogram for predicting ICUAW after CPB.

Methods: Baseline characteristics, preoperative laboratory data, and intra- and postoperative variables of 473 patients after CPB were determined in this prospective cohort study. Lower limb muscles on bedside ultrasound images were compared 1 day before and 7 days after CPB. Risk factors were assessed using logistic regression models.

Results: Approximately 50.95% of the patients developed ICUAW after CPB. The body mass index (BMI), New York Heart Association (NYHA) class, lactate, albumin, aortic clamping time, operation time, and acute physiological and chronic health evaluation II were determined as independent risk factors. The average absolute error of coincidence was 0.019; the area under the curve, sensitivity, and specificity were 0.811, 0.727, and 0.733, respectively, for the predictive nomogram.

Conclusion: A high BMI, poor NYHA class, preoperative high serum lactate, low serum albumin, long surgical duration, aortic clamping, and high acute physiological and chronic health evaluation II score are risk factors for ICUAW after CPB. This robust and easy-to-use nomogram was developed for clinical decision-making.