Accuracy of patient weight estimated by physician and anthropological formulae – a comparison with actual measurement

Introduction: Estimation of weight is important in the intensive care unit but most ICUs do not have a weighing machine for these patients who are unable to stand up. Aim: To compare the accuracy of estimation of weight by the physician, weight estimated using anthropological formulae with actual weight of the patient. Methods: This was a prospective, observational, single centre study. A hundred adult patients, 18-60 years of age, of either gender, waiting for elective surgery in the preoperative waiting area, who were conscious and able to stand were enrolled for the study. The patient's actual weight and height were measured. Experienced anaesthesia consultant unaware of patient's actual weight, was asked to visually estimate the weight of the patient. The patient's height when supine, abdominal girth and length of tibia were measured. Patient's weight was calculated using various anthropological formulae Results: The mean±SD age of the patients was 44.07±14.06 years. 49 were women and 51 were men. There was good correlation between weight estimated by the physician and as calculated by linear regression irrespective of their BMI. Calculated weight was close to actual weight only in patients with normal build but not with low or high BMI. Conclusion: Estimation of patient body weight by an experienced clinician can be fairly reliable. For more objective estimations, linear regression using abdominal and thigh circumference can be used. Anthropometric formulae such as Miller's, Devine's, Robinson's and weight measured using tibial length overestimate weight at low BMI levels and underestimate when BMI is high.