Bedside Estimation of Patient Height for Calculating Ideal Body Weight in the Emergency Department

Stehman, Christine R.; Buckley, Robert G.; Dos Santos, Frank L.; Riffenburgh, Robert H.; Swenson, Aaron; Mulligan, Sheila; Mjos, Nathan; Brewer, Matt

doi:10.1016/j.jemermed.2009.12.016

« Previous Next »The Journal of Emergency Medicine
Volume 41, Issue 1 , Pages 97-101, July 2011

Bedside Estimation of Patient Height for Calculating Ideal Body Weight in the Emergency Department

Christine R. Stehman, MD
- Naval Medical Center, San Diego, California
Robert G. Buckley, MD, MPH
- Naval Medical Center, San Diego, California
- Reprint Address: Robert Buckley, md, Emergency Department, Naval Medical Center San Diego, 34800 Bob Wilson Drive, San Diego, CA 92134
Frank L. Dos Santos, DO
- US Naval Hospital, Naples, Italy
Robert H. Riffenburgh, PHD
- Clinical Investigations Department, Naval Medical Center, San Diego, California
- Mathematics and Statistics Department, San Diego State University, San Diego, California
Aaron Swenson, MSIII
- Dartmouth University Medical School, Hanover, New Hampshire
Sheila Mulligan, MSII
- Uniformed Services University of the Health Sciences, Bethesda, Maryland
Nathan Mjos, DO
- Western University of Health Sciences, Pomona, California
Matt Brewer, DO
- Western University of Health Sciences, Pomona, California

Received 20 April 2009; received in revised form 9 October 2009; accepted 22 December 2009. published online 02 March 2010.

Abstract

Background: Ideal body weight (IBW), which can be calculated using the variables of true height and sex, is important for drug dosing and ventilator settings. True height often cannot be measured in the emergency department (ED). Objectives: Determine the most accurate method to estimate IBW using true height-based IBW that uses true height estimated by providers or patients compared to true height estimated by a regression formula using measured tibial length, and compare all to the conventional 70 kg male/60 kg female standard IBW. Methods: Prospective, observational, double-blind, convenience sampling of stable adult patients in a tertiary care ED from September 2004 to April 2006. Derivation set (215 patients) had blinded provider and patient true height estimates and tibial length measurements compared to gold-standard standing true height. A validation set (102 patients) then compared the accuracy of IBW using true height calculated from the regression formula vs. IBW using gold-standard true height. Regression formula for men tibial length-IBW (kg) = 25.83 + 1.11 × tibial length; for women tibial length-IBW = 7.90 + 1.20 × tibial length; R² = 0.89, p < 0.001. Inter-rater correlation of tibial length was 0.94. Results: Derivation set: percent within 5 kg of true height-based IBW for men/women = Patient: 91.1%:/85.7%; Physician: 66.1%/45.1%; Nurse: 65.7%/ 47.3%; tibial length: 66.1%/63.7%; and 70 kg male/60 kg female standard 46%/75%. Validation set: tibial length-IBW estimates were within 5 kg of true height-ideal body weight in only 56.2% of men and 42.2% of women. Conclusions: Patient-reported height is the best bedside method to estimate true height to calculate ideal body weight. Physician and nurse estimates of true height are substantially less accurate, as is true height obtained from a regression formula that uses measured tibial length. All methods were more accurate than using the conventional 70 kg male/60 kg female IBW standard.

Keywords: ideal body weight, drug dosing, ventilator volume settings, medical error