Authors (including presenting author) :
LUI PSG(1), CHAN HYS(1), TING HYT(1), WONG CY(1), TANG PY(2), LAM KNP(2)
Affiliation :
(1)Department of Dietetics, North District Hospital
(2)Intensive Care Unit, North District Hospital
Introduction :
Under- and over-feeding of calories and nutrients can have detrimental effects on critically ill patients in the ICU, such as malnutrition, poor wound healing, increased rates of infection and difficulty weaning from the ventilator- and has direct correlation with increased length of stay, higher mortality rates and costs. The conventional method of predictive equations is routinely used to estimate energy expenditure (EE), but is frequently reported by validation studies to have lower performance when compared to Indirect Calorimetry. Indirect Calorimetry remains the international gold standard technology in measuring energy requirements- however rarely used in local clinical practice due to unavailability of calorimeters, lack of expertise and manpower on device operation. This is the first study in our locality comparing the accuracy of the conventional method of estimating EE with predictive equations against actual measured EE by Indirect Calorimetry.
Objectives :
1) To test the hypothesis that energy requirements estimated by predictive equations would be significantly different from the requirement measured by Indirect Calorimetry
Methodology :
In a service evaluation exercise, a single-center, retrospective cohort analysis was conducted in 12 mechanically ventilated patients aged >20 who were admitted to the North District Hospital ICU between January 2016 to December 2018. Energy requirements estimated by the validated predictive equation (ASPEN 2016 guideline- 25-30kcal/kg/day) were compared against measured energy requirements with Indirect Calorimetry using the Wilcoxon Signed Rank Test and Lin’s Concordance Correlation Coefficient Test.
Result & Outcome :
1) The hypothesis was proven that there is a significant difference of 499±12.75calories/day (p<0.01) between estimated energy requirements with predictive equations compared to Indirect calorimetry. This indicates that predictive equations significantly under-estimated energy requirements. Based on Lin’s Concordance Correlation of ρc 0.178 (95% CI, 0.0233 –0.3251), the strength of agreement between the conventional method using predictive equation is weak and have lower performance when compared to the gold standard Indirect Calorimetry. 2) There is a significant improvement of 38.1±11.25% (p<0.01) in energy provision after intervention- an improvement of 270±11.25calories/day (p<0.01). This result has led to a change of nutrition prescription in 83% of our analyzed patients. We recommend that Indirect Calorimetry is needed to provide optimal nutritional delivery and improve outcomes for mechanically ventilated ICU patients. Further and larger-scale studies comparing the difference between predicted versus measured EE with Indirect Calorimetry should be considered.
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