Seeing Isn't measuring: ICU staff's ability to estimate patient height and weight - A cross-sectional study from Pakistan's largest cardiac centre

Abstract

Objective: In critical care, intensive care unit (ICU) staff and physicians often estimate patients' height and weight visually, impacting calculations for cardiac function, ventilation, medication, nutrition and renal function. However, accurate assessment is challenging in critically ill patients. This study evaluates the accuracy of visual estimations by ICU staff.

Design: Descriptive cross-sectional study.

Setting: National Institute of Cardiovascular Diseases, Karachi, Pakistan.

Participants: We included a convenient sample of adult (≥18 years) cardiac patients admitted to the critical care unit in this study. Patients who refused to give consent, trauma/surgery of lower limbs or patients with below-knee or above-knee amputation were excluded to avoid bias.

Outcome measure: A convenient sample of cardiac ICU patients was included. Measured weight (kg) and height (cm) were compared with visual estimations by senior ICU nurse, senior non-ICU nurse, ICU consultants, fellows and residents. Correlation and agreement were analysed using Bland-Altman plots and 95% agreement limits.

Results: A total of 356 patients were evaluated, of whom 204 (57.3%) were male, with a mean age of 55.2 ± 14.3 years. The median SOFA score was 3 [2-5], and 101 patients (28.4%) were on mechanical ventilation. The mean difference between measured and estimated weight by senior non-ICU nurse was 4.7±9.2 [-13.38-22.83] kg, senior ICU nurse was 7.8±9.9 [-11.56-27.12] kg, ICU consultants was 3.0±6.6 [-9.89-15.79] kg, ICU fellow was 3.0±7.1 [-10.88-16.92] kg and ICU resident was 8.0±9.6 [-10.83-26.79] kg. Similarly, the mean difference between measured and estimated height by senior non-ICU nurse was 2.0±7.3 [-12.36-16.34] cm, senior ICU nurse was 2.4±7.5 [-12.19-17.00] cm, ICU consultants was 1.5±5.6 [-9.51-12.48] cm, ICU fellow was 1.1±5.5 [-9.68-11.95] cm and ICU resident was 2.3±8.5 [-14.40-19.01] cm.

Conclusion: The findings indicate that healthcare professionals tend to overestimate both weight and height. The accuracy of these estimations varied among professional groups, underscoring the potential clinical consequences of such errors. This emphasises the need for objective measurements in clinical decision-making.

Keywords: Adult cardiology; Health Services; Intensive Care Units.

Figure 1. Bland–Altman plots for measured and VEheight and weight by various healthcare professionals. VE, Visually Estimated.

Figure 2. Distributing body mass index through VE height and weight by various healthcare professionals. ICU, intensive care unit.