Precision of weight measurement in critically ill infants: a technical report

Objectives: To investigate the precision of weight measurements in critically ill infants in a paediatric intensive care unit (PICU). Design: Prospective cohort study. Setting: Royal Children's Hospital PICU. Participants: Mechanically ventilated infants admitted to the Royal Children's Hospital PICU between September 2020 and February 2021. Main outcome measures: Mean percentage difference and agreement of consecutive weight measurements. Results: Thirty infants were enrolled, of which 17 were receiving post-surgical care for congenital heart disease and four were receiving extracorporeal membrane oxygenation (ECMO). The median age was 13 days (interquartile range [IQR], 3.1–52.4 days). The mean difference in weight was 1.3% (standard deviation [SD], 1.0%), and the test–retest agreement intraclass correlation was 0.99 (95% CI, 0.99-0.99; P < 0.01). The percentage difference between measurements was ≤ 2.5% in 26/30 (87%) children, and the range was < 0.1% to 3.6%. In 26 children not receiving ECMO, the mean difference in weight was 1.1% (SD, 1.0%). There were no complications. Conclusions: Weighing mechanically ventilated, critically ill infants in intensive care can be performed safely, with a mean difference between consecutive weights of 1.3%, making it a potentially useful additional measure of fluid accumulation.