In adult medicine, determining the patient's body weight by visual estimation performed
by healthcare providers (nurses and doctors) is common for critically ill patients who
cannot speak or stand due to acute illnesses such as loss of consciousness, circulatory
shock, or acute respiratory failure. This practice often leads to the administration of
the same dose of medication to many patients whose body weight may vary between 50 to 100
kilograms (kg). In cases where rapid diagnosis and treatment are crucial due to acute
illness, the accurate and effective administration of dose-dependent drugs such as
antibiotics, anticoagulants, vasopressors, sedatives, and analgesics is essential for
treatment success. Although the average error percentage of 10-20% in estimated body
weight by visual estimation may seem negligible in emergencies, it can lead to increased
toxicity and costs in recombinant factor replacements, anticoagulants with a narrow
therapeutic range, and various imported antibiotics. Additionally, the high error rate in
estimating height by visual estimation poses a risk of causing ventilator-induced lung
injury (VILI) during invasive mechanical ventilation support by inducing alveolar
overdistension.
Various calculation methods have been reported for estimating body weight based on
anthropometric measurements. One such method is weight calculation based on the upper
mid-arm circumference (UMAC), which has been reported as the most correlated calculation
for actual body weight in the adult age group in studies using National Health and
Nutrition Examination Survey (NHANES) data in the United States (U.S.). Another commonly
used method is formulas that calculate ideal body weight based on the patient's height.
This is especially crucial in critically ill patients during invasive mechanical
ventilation support for acute respiratory failure. The calculation of ideal body weight
using charts based on half-span or knee height can be applied in cases where patients
cannot stand due to critical illness.
Many anthropometric measurements mentioned here have been conducted in different
societies. They may vary according to ethnic communities, emphasizing the potential
differences in body composition, such as fat and muscle mass distribution, among
different ethnic groups. Considering the critical illness in the Turkish population,
there is currently no detailed publication in the literature regarding the usability of
estimated body weights calculated based on anthropometric measurements. Moreover, the
fact that many anthropometric measurements are derived from population screening data in
healthy individuals causes their application in clinical practice challenging. Validity
of anthropometric measurements that apply to critically ill patients, where patients
cannot stand, appropriate positions for anthropometric measurements cannot be provided,
and body distributions in limbs where anthropometric measurements are derived may differ
due to peripheral edema, is, therefore, crucial.
In many studies using anthropometric measurements for weight calculation, the actual body
weights of patients were measured using a calibrated scale. Given that critically ill
patients often cannot be lifted due to acute illness, special devices or equipments are
needed to reliably determine actual body weights in the supine position in this patient
group. Currently, used bed scales, wall-mounted levers, or special devices that allow the
patient and bed to be weighed together are not widely used due to high costs and
difficulties associated with patient transfer from bed to bed, such as the need for the
patient to be hemodynamically stable, the need for multiple personnel during patient
transfer, adherence to infection prevention rules, and the time-consuming nature of
measurements depending on the device used. The recently developed patient transfer scale,
Marsden M-999®, which has advantages for patients who cannot stand, suggests that it
could be used to calculate actual weight rapidly and accurately in critically ill
patients. There is no publication currently in the literature about the routine use of
the mentioned patient transfer scale in critically ill settings. However, its ease of use
in measuring patient body weight in the supine position while transitioning from a
stretcher to an intensive care bed is a significant advantage.
Considering that the patient transfer scale cannot be provided to every intensive care
unit due to its cost; it was aimed to determine the most valid estimated body weight
calculation method in the critically ill Turkish patients according to anthropometric
measurements in this study.