Accuracy and ease of use of a novel electronic urine output monitoring device compared with standard manual urinometer in the intensive care unit.

INTRODUCTION

Urine output (UO) is a critical parameter in the intensive care unit not yet electronically monitored. This study tested the accuracy and ease of use of a new electronic continuous UO monitoring device (Urinfo 2000; Medynamix, Jerusalem, Israel).

METHODS

This article is a prospective study in a 6-bed intensive care unit. In consecutive patients with indwelling urinary catheter and expected stay of 24 hours or more, hourly UO was measured by either Urinfo or manual urinometer, validated by cylinder measurements. Overall accuracy was assessed comparing each method with the cylinder, using regression analysis, Bland-Altman plots, and, for UO of 40 mL/h or less, standard evaluation of diagnostics. Staff satisfaction was assessed by a short questionnaire.

RESULTS

In 20 patients, 453 measurements were obtained, 167 by urinometer and cylinder and 286 by Urinfo and cylinder. The mean relative percentage deviation from the cylinder measurement was 8% and 26% for the Urinfo and urinometer, respectively (P < .05). Bland-Altman plots of each method vs the cylinder showed a better agreement with the Urinfo. Positive predictive value for UO of 40 mL/h or less (cylinder as criterion standard) was 91% and 77% for the Urinfo and urinometer, respectively. The questionnaire revealed an 87% satisfaction with the Urinfo.

CONCLUSIONS

Urinfo is significantly more accurate and "user friendly" than the urinometer. It promises future incorporation of these data into patient data management systems for the benefit of patients' management.