Authors (including presenting author) :
LEE LK(1); LEE SP (2); SINN TTM (3); POON YC (4), CHING CK(5)
Affiliation :
(1) Dietitian i/c, KEC Dietetic Department, Tseung Kwan O Hospital (2) Dietetic Departmental Manager, Kowloon East Cluster (3) Associate Consultant, Department of Medicine, Tseung Kwan O Hospital (4) Ward Manager, Department of Intensive Care Unit, Tseung Kwan O Hopital (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 difference in HB-derived energy expenditure (HB-EE), WB-derived energy expenditure (WB-EE) and IC-measured EE (IC-EE). Also how can dietitian provide more precisely nutrition plan especially for repeated measurements among the prolonged ICU stay patients.
Methodology :
ICU medical officers screened and referred to dietitian for IC measurement once a week. Nurses would assist in preparing the patients by following a protocol such as the avoidance of excessive passive movement, repositioning and vigorous procedures 2-hour prior to IC measurement. Also repeated measurements would be carried out for those patients with more than 7 days’ ICU stay. Data on HB-EE, WB-EE, IC-EE and Body Mass Index (BMI) were collected. Pearson’s correlation analysis and one-way ANOVA analysis were used to examine the relationship between different variables. To analyze the precision of different equations, it was set as within 10% of IC-EE.
For those repeated measurements, we tried to see any trend in changes in energy requirement with time. Nutrition regimen would be modified according to these changes. Target goal should be set at 70% or above of IC-EE.
Result & Outcome :
A total of 93 measurements were performed on 78 patients. Their parent specialties were 57% medical, 37.6% surgical, 4.3% orthopaedics and 1.1% gynaecology. Pearson’s correlation coefficient test indicated that there was a significant relationship between BMI and IC-EE (r = 0.406, p=0.000). For HB-EE, only 31 calculated values could be matched within +/-10% of IC measurements. Its precision should be 33.3%. 39 HB-EE values underestimated the patients’ requirement (by 121 up to 1115 kcal/day deficit). For the WB-EE, 21 calculated values could match with IC results. Its precision should be 22.5%. 59 WB-EE values would over-estimate the patients’ requirement (ranging from 167.5 to 2658.5 kcal/day excessive).
10 patients had been measured at least twice during their long ICU stay. 7 out of 10 (70%) showed increasing their energy requirement by 21.6% to 73.3%. While 3 out of 10 (30%) showed a decrease in their energy need by 9.6% to 11.8%. Nutrition regimens were changed according to their changes in requirement. Only 70% of them could achieve their target energy goals. Reasons for the hindering of either enteral or parenteral nutrition support were high gastric residual volume and deranged liver function.
One-way ANOVA analysis also indicated that the energy requirements of surgical patients were higher significantly than medical patients across all BMI categories.
Conclusion:
Both HB and WB equations cannot precisely match with the gold standard. Their precisions are around 22-33% 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. Also, it is observed that requirement changed significantly with the time. It is difficult to anticipate and predict the hectic changes in requirement in different metabolic states. Therefore, it is essential to have repeated measurements for prolonged ICU stay patients. Surgical ICU cases are suggested to have higher priority in offering indirect caloriemetry measurement.
