Authors (including presenting author) :
LEE LK(1), SINN TTM(2), POON YC(3), LEE SP(4), CHING CK(5)
Affiliation :
(1) Dietitian i/c, KEC Dietetic Department, Tseung Kwan O Hospital,(2) Associate Consultant, Department of Medicine, Tseung Kwan O Hospital, (3) Ward Manager, Department of Intensive Care Unit, Tseung Kwan O Hospital, (4) Allied Health Clinical Service Coordinator/Dietetic Departmental Manager, Kowloon East Cluster, (5) Consultant, Department of Medicine, Tseung Kwan O Hospital
Introduction :
In many ICU settings, dietitians often assess the patients’ energy requirement by following an international guideline on weight-based (WB) equation (25kcal/kg body weight/day) or certain validated predictive equations such as Harris-Benedict (HB). However, it is well known that these estimates lack precision and may lead to overfeeding or underfeeding. In an attempt to promote quality nutrition support for this patient population, Indirect Calorimetry (IC) was introduced in early January 2018 to tailor-made nutrition intervention for patients in ICU of Tseung Kwan O Hospital (TKOH), Hospital Authority, HKSAR.
Objectives :
This study aimed at investigating the differences in HB-derived energy expenditure (HB-EE), WB-derived energy expenditure (WB-EE) and IC-measured EE (IC-EE).
Methodology :
Medical officers from TKOH ICU screened and referred to dietitian for IC measurement. Nurses would assist in preparing the patients by following a protocol such as avoidance of excessive passive movement, repositioning and vigorous procedures 2-hour prior to IC measurement. Data on HB-EE, WB-EE, IC-EE and Body Mass Index (BMI) were collected. Pearson’s correlation analysis was used to examine the relationship between BMI and IC-EE. To analyze the precision of different equations, it was set as within +/-10% of IC-EE. If the majority (> or =50%) of individual difference of equation-derived EE was greater than 10% of the gold standard, the equations should be considered as inaccurate.
Result & Outcome :
A total of 42 measurements were performed on 36 patients. Pearson’s correlation coefficient test indicated that there was a significant relationship between BMI and IC- EE (r = 0.396, p=0.009). For HB-EE, 9 (21.4%) should be matched within 10% of IC measurements. Its precision should be 21.4%. 22 (52.4%) would underestimate the patients’ requirement (less than 94-1115kcal/day). 11(26.2%.)would overestimate the patients’ requirement (more than 123-1515kcal/day). For the WB-EE, 9 (21.4%) can match with IC results. Its precision should be 21.4%. 21(50%) would over-estimate the patients’ requirement (with more than 167.5-673kcal/day). 12 (28.6%) would underestimate patients’ requirement (with less than 174-1028kcal/day). Conclusion: Both HB and WB equations cannot precisely match with the gold standard. Their precisions are around 21.4% in this study which is consistent with other bigger international studies. HB equation tends to underestimate patients’ requirement while WB equation tends to overestimate patients’ need. Therefore, meticulous measurement of energy expenditure using Indirect Calorimetry is essential to avoid overfeeding or underfeeding. In this study we also found that there may a non-linear relationship between BMI and measured energy expenditure. Further investigations should be explored.
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