Continuous Urine Output Monitoring Improves ICU Accuracy Post-CABG

CONTINUOUS urine output monitoring provided substantially greater measurement accuracy than visual inspection in patients recovering from coronary artery bypass grafting (CABG), according to new research conducted in a post-cardiac surgery intensive care unit.

The findings suggest that continuous urine output monitoring may offer a more reliable approach to assessing renal function in the immediate postoperative period.

Evaluating Continuous Urine Output Monitoring in the ICU

Acute kidney injury is a recognised complication following CABG and is commonly identified through changes in serum creatinine and urine output.

Although urine output remains a key clinical parameter, it is often measured through visual inspection of urine collection bags, a method that may be prone to observer error.

To evaluate a potential alternative, researchers compared a continuous electronic urine output monitoring system against visual inspection, using graduated cylinder measurements as the reference standard.

The prospective observational study included 52 post-CABG patients and generated 936 hourly urine output measurements over a 6-hour monitoring period.

Each patient underwent simultaneous assessment using visual inspection, the electronic monitoring device, and graduated cylinder measurement.

Agreement With Gold Standard Measurements

Analysis showed excellent agreement between continuous urine output monitoring and graduated cylinder measurements.

By comparison, visual inspection demonstrated lower agreement with the reference standard. Scatter plot analysis further highlighted the difference between methods.

Measurements obtained with the electronic system closely aligned with the line of equality, whereas visual inspection consistently overestimated urine output relative to the gold standard.

Reduced Bias and Clinical Implications

Bland-Altman analysis also favoured continuous urine output monitoring. The electronic device demonstrated a mean bias of 4.4 mL, whereas visual inspection showed a mean bias of 31.2 mL.

Researchers noted that conventional monitoring frequently involved delayed recording, estimation of average urine output over several hours, or omissions in documentation.

By contrast, the electronic system delivered automated hourly measurements and real time data capture.

The authors concluded that continuous urine output monitoring measured and recorded hourly urine output significantly more accurately than visual inspection in post-CABG patients in the intensive care setting.

They suggested that accurate, real-time monitoring may provide a stronger foundation for clinical decision making and future investigations assessing the impact of electronic monitoring on patient outcomes.

Reference

Alimohammadi B et al. Comparative accuracy of continuous electronic urine output monitoring in the post-cardiac surgery intensive care unit. Sci Rep. 2026;DOI:10.1038/s41598-026-70497-3.

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