Measured vs Predicted Energy Expenditure in Mechanically Ventilated Adults With Acute, Traumatic Spinal Cord Injuries.

BACKGROUND: Research regarding the impact of acute spinal cord injury (aSCI) on energy expenditure is limited. Patients with aSCI are prone to complications of both over- and under-feeding, making appropriate nutrition support pivotal to patient care. The purpose of this study was to describe energy expenditure and assess the performance of predictive equations in mechanically ventilated adults with aSCI. METHODS: Adult patients admitted to a single trauma center from March 2017 through June 2018 with aSCI and a documented indirect calorimetry (IC) within 6 weeks of injury were included for analysis. Predictive equations evaluated included Penn State 2003b (PS 2003b), the derived Weir equation, 25 kcal/kg and 30 kcal/kg. Sub-set analysis was performed for patients with and without obesity, isolated aSCI, and concomitant traumatic injuries. RESULTS: On hundres fifteen IC studies in 51 patients were included for analysis. Median energy expenditure was 1747 kcal/day (interquartile range [IQR], 1492-2099 kcal/day), or 22.7 kcal/kg (IQR, 19.3-25.9 kcal/kg). When stratified by hospital day, energy expenditure ranged from 20 to 25 kcal/kg. PS 2003b and the derived Weir equation had similar correlation coefficients (r = 0.81 and 0.82, respectively). The 25 and 30 kcal/kg performed unacceptably (r = 0.61). PS 2003b predicted within 10% of measured energy expenditure most frequently. All equations were biased towards overfeeding, except for PS 2003b in the obese subset. CONCLUSION: In the absence of IC, PS 2003b or the derived Weir equation may be acceptable predictive equations in this population. However, bedside clinicians should monitor carefully for signs and symptoms of overfeeding.

Validation of predictive equations to assess energy expenditure in acute spinal cord injury.

BACKGROUND: Acute spinal cord injury (SCI) is devastating with morbidities compounded by inadequate nutrition. The American Society for Parenteral and Enteral Nutrition recommends indirect calorimetry (IC) to evaluate energy needs in SCI because no predictive energy equations have been validated. We sought to determine the accuracy of predictive equations to predict measured energy expenditure (MEE). METHODS: A retrospective review was performed over 2 years. Patients 18 years or older with cervical SCI who received IC were included. Height, weight, maximum temperature and minute ventilation on day of IC, plus MEE and VCO2 from IC were obtained. Predicted energy expenditure (PEE) was calculated using Harris-Benedict (HB), Penn State (PS), Mifflin St. Jeor (MSJ), Weir, Ireton-Jones (IJ), and 25 kcal/kg formulas. MEE was then compared to the PEE of each method. RESULTS: Thirty-nine IC studies were completed for 20 patients. Weir had the strongest correlation to MEE (r = 0.98), followed by PS (r = 0.82). Correlations were similar among HB (r = 0.78), MSJ (r = 0.75), and IJ (r = 0.73), and weakest with 24 kcal/kg (r = 0.55). All had a p value <0.001. Deming regression confirmed strong correlations between Weir and PS to MEE, with coefficients of 1.03 and 1.515 (p < 0.001), respectively. Other formulas had comparatively higher coefficients and standard errors. Bland-Altman analysis confirmed Weir had the narrowest range of difference, with a mean difference of 25.5 kcal/day, followed by PS (-336.1 kcal/day). CONCLUSIONS: Weir is the best predictive energy equation, with all statistical tests demonstrating a strong correlation between MEE and Weir. The second best predictive equation is the Penn State formula, which predicts actual MEE measured by IC with high accuracy. LEVEL OF EVIDENCE: Diagnostic study, level III.