Analysis of Factors Influencing Downtime During Continuous Renal Replacement Therapy in Critically Ill Patients and Construction of a Prediction Model

Prolonged CRRT downtime compromises treatment efficacy and worsens outcomes. Daily downtime > 20% exacerbates acidosis and is associated with 28-day mortality.

This study aimed to develop and validate a bedside-accessible nomogram for early identification of treatment days at risk of suboptimal CRRT downtime control in critically ill patients.

This retrospective cohort study was conducted in one Chinese ICU (January 2019-December 2023). The binary outcome was cumulative downtime > 2.4 h per standardised treatment day. Variables included demographics, laboratory parameters, CRRT circuit and other treatment factors. GEE identified predictors; the model was displayed as a nomogram and assessed by AUC, calibration and decision curve analysis.

A total of 145 patients contributing 595 CRRT treatment days were included. Total treatment time was 14 280 h and cumulative downtime was 1725.07 h. Mean daily downtime was 2.90 ± 2.72 h (12.08% ± 11.35% of treatment time). Suboptimal CRRT downtime control occurred on 232 treatment days (39.0%). Multivariable GEE analysis identified five independent risk factors for suboptimal downtime control: daily number of filter replacements (OR = 2.629, 95% CI 1.822-3.794, p < 0.001), agitation (OR = 2.331, 95% CI 1.041-5.218, p = 0.040), plasma exchange (OR = 4.654, 95% CI 1.042-20.782, p = 0.044), catheter dysfunction (OR = 10.528, 95% CI 2.939-37.710, p < 0.001) and out-of-unit transport for procedures (OR = 7.563, 95% CI 2.663-21.484, p < 0.001). The nomogram yielded AUCs of 0.789 (95% CI 0.726-0.841), 0.813 (95% CI 0.725-0.897) and 0.835 (95% CI 0.768-0.896) in the training, internal validation and external validation sets, respectively.

Daily number of filter replacements, agitation, plasma exchange, catheter dysfunction and out-of-unit transport are independent risk factors for suboptimal CRRT downtime control. This nomogram showed satisfactory discrimination, calibration and net clinical benefit in internal and external validation, offering ICU nurses a rapid bedside risk assessment tool.

ICU nurses can use this nomogram at CRRT initiation to identify high-risk patients and prioritise bedside procedures, sedation, catheter care and filter longevity to reduce downtime.