Bedside Method to Estimate Actual Body Weight in the Emergency Department

BackgroundActual body weight (ABW) is important for accurate drug dosing in emergency settings. Oftentimes, patients are unable to stand to be weighed accurately or clearly state their most recent weight.ObjectiveDevelop a bedside method to estimate ABW using simple anthropometric measurements.MethodsProspective, blinded, cross-sectional convenience sampling of adult Emergency Department (ED) patients. A multiple linear regression equation from Derivation Phase (n = 208: 121 males, 87 females) found abdominal and thigh circumferences (AC and TC) had the best fit and an inter-rater correlation of 0.99 and 0.96, respectively: Male ABW (kg) = −47.8 + 0.78 ∗ (AC) + 1.06 ∗ (TC); Female ABW = −40.2 + 0.47 ∗ (AC) + 1.30 ∗ (TC).ResultsDerivation phase: Number of patients (%) with a body weight estimation (BWE) > 10 kg from ABW for males/females were: 7 (6%)/1 (1%) for Patients, 46 (38%)/28 (32%) for Doctors, 38 (31%)/24 (27%) for Nurses, 75 (62%)/43 (49%) for 70 kg/60 kg convention, and 14 (12%)/8 (9%) using the anthropometric regression model. For validation phase (55 males, 44 females): Gold standard ABW mean (SD) male/female = 83.6 kg (14.3)/71.5 kg (18.9) vs. anthropometric regression model = 86.3 kg (14.7)/73.3 kg (15.1). R2 = 0.89, p < 0.001. The number (%) for males/females with a BWE > 10 kg using the anthropometric regression model = 8 (15%)/11 (27%).ConclusionsFor male patients, a regression model using supine thigh and abdominal circumference measurements seems to provide a useful and more accurate alternative to physician, nurse, or standard 70-kg male conventional estimates, but was less accurate for use in female patients.