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A Pilot Evaluation of a Capacitance-Based Automatic Urinometer in a Pediatric Intensive Care Setting

Slettengren, Martin MD1,2; Wetterfall, Hanna MD2; Eklund, Anton MD2; van der Linden, Jan MD, PhD1,2

Pediatric Critical Care Medicine: August 2019 - Volume 20 - Issue 8 - p 769-772
doi: 10.1097/PCC.0000000000002000
Renal Critical Care

Objectives: To compare a modified capacitance-based automatic urinometer to a manual urinometer, with regard to precision of measurement and to evaluate the staff’s opinion regarding the automatic urinometer.

Design: Prospective observational cohort study.

Setting: PICU at Astrid Lindgren’s Children Hospital in Solna, Sweden.

Patients: Twelve children weighing up to 10 kg with an indwelling urinary catheter in place before enrollment.

Interventions: Measurement of hourly diuresis using either an automatic urinometer or manual urinometer.

Measurements and Main Results: Hourly diuresis was measured with an automatic urinometer (n = 127; Sippi; Observe Medical Nordic AB, Gothenburg, Sweden) or an manual urinometer (n = 83; Unometer Safeti Plus; Convatec, Lejre, Denmark) and thereafter validated with a measuring cylinder. The absolute mean bias was –1.1 mL for the automatic urinometer (CI, –0.6 to –1.5) and –0.6 mL (CI, ± 0.0 to –1.2) for the manual urinometer (p = 0.21). The sds were 2.6 and 2.8 mL, respectively. User evaluation comparing the automatic urinometer with the manual urinometer concerning the ease of use was made with a questionnaire (n = 18). The majority of staff preferred the automatic urinometer to the manual urinometer in terms of ease of use, learning, and handling.

Conclusions: The two urinometers were comparable in performance for children weighing up to 10 kg. Taking into account the overwhelming staff satisfaction with the automatic urinometer and benefits in less well-staffed wards as well as lack of temporal deviation, the modified automatic urinometer may be considered for clinical use in the PICU.

1Division of Perioperative Medicine and Intensive Care, Section of Cardiothoracic Anesthesiology and Intensive Care, Karolinska University Hospital, Stockholm, Sweden.

2Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.

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Dr. Wetterfall disclosed that the company that manufactures the automatic urinometer loaned the investigators the two urinometers used in the study, free of charge. The remaining authors have disclosed that they do not have any potential conflicts of interest.

Ethical permission was obtained for this study by the regional ethical review board in Stockholm (approval number 2015/666-32).

Address requests for reprints to: Martin Slettengren, MD, Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 77, Stockholm, Sweden. E-mail:

Copyright © 2019 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies