Difference between estimated and actual body weight in an intensive care unit—A service evaluation

Actual body weight (ABW) is important for drug dosing and calculating nutritional requirements. The aim of this study is to establish the difference between ABW and estimated body weight in a cohort of ICU patients. Our service evaluation compared 100 patients whose weights were initially estimated by staff, and if able by patients also. Weights were then measured. We also compared ABW to Ideal and Predicted Body Weights. We had a ⟩10% error margin in 36% of estimated weights and a ⟩ 20% error margin in 11% of estimated weights. Median error for patients self-estimating their body weight was 4.14% (IQR 1.39-7.74). For patients that were able to estimate their weight the median error margin was 4.14% (IQR 1.39-7.74). The Median difference between ABW and Ideal Body Weight was 18.57% (IQR 9.78-36.57) and 18.15% for ABW and Predicted Body Weight (IQR 9.13-36.58). Estimated body weights should only be used when weighing patients is contraindicated. Patients are more accurate at estimating their own body weight than staff. It is best practice to accurately measure body weight in ICU patients.