The importance of indirect calorimetry in the management of nutrition in major burns: a retrospective study

Dr James Leung1, Dr Susannah King1, Mr Elhdo  Paul1,3, Dr  Josh Ihle1, Ms Emma Ridley1,3, Ms Heather Cleland1,2

1Alfred Health, Melbourne, Australia, 2Department of Surgery Central Clinical School, Monash University, Melbourne, Australia, 3Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia

Objectives: To investigate how measured energy expenditure (mEE) via indirect calorimetry in major burns patients changes over time. To compare mEE with predicted energy requirements (pER) via four commonly used prediction energy equations.

Methods: Data was retrospectively analysed on 29 major burns patients age 46±18years, %TBSA burn 35±17%) admitted to an Intensive Care Unit between 2013-2015. Indirect calorimetry (Cosmed Quark) was performed on patients on 1-4 occasions throughout the ICU admission to measure EE (n=46), which was divided by predicted basal metabolic rate to calculate degree of EE elevation (%mEE). pER were calculated using modified Schofield, modified Harris-Benedict, Ireton-Jones and Curreri equations, adjusted using recommended stress factors. Bland-Altman Analysis and Spearman Correlation were performed.

Results: Mean±SD mEE was 9752±2089kJ/day (%mEE:  143±32%). A significant and positive correlation was found between %mEE and day post-burn (r=0.35, p=0.016), and between %mEE and number of surgeries (r=0.34, p=0.02). Bland-Altman Analysis displayed substantial variability between mEE and pER for all equations. Mean differences and 95% limits of agreement (LOA) were 54±2373kJ/day (95% LOA -4700 to 4802kJ/day) for the Schofield equation; -1728±2784kJ/day (95% LOA -7300 to 3839kJ/day) for the Harris-Benedict equation; -1276±2092kJ/day (95% LOA-5500 to 2907kJ/day) for the Ireton-Jones equation; and -4476±3402kJ/day (95% LOA -11000 to 2327kJ/day) for the Curreri equation.

Conclusion: There is substantial variability in measured energy expenditure within and between major burns patients, and clinically significant discrepancies between measured energy expenditure and prediction equations.  This study emphasises the importance of indirect calorimetry as standard practice in major burns patients to ensure appropriate nutrition.

James Leung is a surgical resident at the Alfred Hospital in Melbourne, Victoria. He is currently interested in pursuing a career in plastic and reconstructive surgery, with a particular interest in trauma and burns. He has most recently completed a masters of trauma sciences through Barts and The London School of Medicine and Dentistry.

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