Fluid balance is essential to patients’ health, and fluid balance disorders are associated with increased mortality, complications and prolonged hospitalization. Thus, monitoring fluid balance is an essential nursing task. However, fluid balance charting is often inadequate due to increased acuity, lack of time, knowledge and skills of staff. In addition, fluid measurements are often based on staff estimates and thus inaccurate. The aim of the study was to assess the measurement accuracy using innovative technology compared to accurate manual measurements and standard procedure to determine its application in actual clinical practice as a first step pilot study.
The Scientific Ethics Committee approved the study. We recruited patients during their admission to the Urology Department and all participants provided informed consent. In this study, we tested the innovative device ‘LICENSE’ (Liquid balance monitoring system) which wirelessly measures fluid intake and output and transfers data to a database that presents data by numbers and graphs. It consists of three devices: 1) for intravenous fluids 2) for oral intake and 3) for urinary output in catheter. We connected participating patients to LICENSE and every hour we performed both an accurate manual measurement by weighing the fluids and a manual reading, which is standard procedure. At the same time, LICENSE obtained data. We evaluated the agreement between methods by comparing accurate manual weight to either LICENSE or manual reading using Bland Altman plots.
We observed 10 patients (mean age: 78.1 years; 70% men) on average for 6 hours and performed 437 measurements (165 by LICENSE, 165 manual weights and 107 manual readings).
The mean deviation of measuring urinary output was -4.5 ml (95% CI: -6.7 to -2.3) ±15.5 ml by LICENSE and 12.5 ml (95% CI: 10.6 to 14.4) ±13.1 ml by manual reading. The mean deviation of oral fluids was -3.2 ml (95% CI: -5,2 to -1,2) ±14.9 ml by LICENSE and 6.2 ml (95% CI: 2.8 to 9.6) ±25 ml by manual reading. The deviation of intravenous fluids was -1.8 ml (95% CI: -2.7 to -0.8) ±6.9 ml by LICENSE.
We found a systematic bias between manual weight and both LICENSE and manual reading, however less by LICENSE. In comparison to standard procedure, the measurement accuracy was equivalent or improved using LICENSE. Thus, digital fluid balance monitoring by LICENSE is safe and might improve measurement accuracy in clinical practice. However, this requires further examination. In addition, LICENSE has some benefits over conventional fluid balance charting in timeliness e.g. in hourly measurements and by reducing human errors. Further, it may free up time for other nursing tasks.