Ultrasound-assisted dynamic bladder function for predicting successful catheter removal in male ICU patients: a prospective cohort study

Optimal timing for urinary catheter removal in intensive care unit (ICU) patients remains challenging, as conventional static measurements often fail to accurately reflect true bladder function in the critically ill. This study aimed to evaluate the predictive value of ultrasound-assisted bladder emptying dynamics for successful spontaneous voiding and to develop a practical predictive nomogram for male ICU patients. This prospective observational cohort study included male ICU patients scheduled for urinary catheter removal between July 2021 and October 2023. Bladder emptying time, actual bladder capacity, and intravesical pressure at 200 ml (P200) were dynamically measured using a standardized saline infusion protocol with bedside ultrasound assistance. The primary outcome was successful spontaneous voiding within 24 h after catheter removal. Multivariable logistic regression was utilized to identify independent predictors and construct a nomogram. Model performance was assessed via discrimination, calibration, and decision curve analysis, with internal validation using 1,000 bootstrap resamples. A total of 87 patients were included, of whom 60 (69.0%) achieved successful spontaneous voiding. Multivariable analysis revealed that a longer bladder emptying time (OR: 0.992, 95% CI: 0.985–0.997; P = 0.009) and a larger actual bladder capacity (OR: 0.991, 95% CI: 0.983–0.998; P = 0.023) were independently associated with a decreased likelihood of successful voiding. In contrast, static P200 was not a significant predictor ( P = 0.763). The developed nomogram demonstrated acceptable discrimination (apparent AUC = 0.766; optimism-corrected AUC = 0.721) and excellent calibration (Brier score = 0.176). Decision curve analysis indicated a higher net clinical benefit compared with empirical "treat-all" or "treat-none" strategies. Ultrasound-assisted dynamic bladder functional parameters may offer potential clinical utility for predicting voiding outcomes after catheter removal in ICU patients, providing additional functional insights compared to conventional static manometry. The proposed non-invasive nomogram may serve as a practical, physiology-driven tool to support individualized bedside decision-making.