Clinical Nutrition Espen · 4 authors, 2 centres
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This prospective cohort study measured resting energy expenditure (REE) in 20 mechanically ventilated COVID-19 patients using indirect calorimetry and found them to be normocaloric during the acute phase. Prescribed energy and protein were significantly lower than measured REE, consistent with ESPEN guidelines recommending hypocaloric feeding in early critical illness. The findings support current practice but highlight a gap between measured energy needs and actual delivery.
**Background:** Ensuring adequate nutrition in critically ill COVID-19 patients is challenging due to inflammatory and metabolic derangements that alter energy expenditure and nutritional requirements. The optimal approach to energy delivery in this population remains uncertain, particularly during the acute phase of illness. This study aimed to determine resting energy expenditure (REE) in critically ill COVID-19 patients using indirect calorimetry and to assess whether prescribed nutrition conformed to locally implemented protocols based on ESPEN guidelines.
**Methods:** This was a prospective cohort study conducted in a single intensive care unit. Inclusion criteria were critically ill adult COVID-19 patients requiring invasive mechanical ventilation. REE was measured using ventilator-derived VCO2 indirect calorimetry (mREE). Predicted REE (pREE) was calculated using ESPEN recommendations (20 Kcal/Kg of actual body weight, or adjusted body weight if BMI >30). Data were also collected on prescribed energy (prE) and protein amounts (recommended and prescribed). Comparisons were made between mREE and pREE, mREE and prE, and 70% of mREE versus prE to evaluate conformity with the unit's ESPEN-based feeding protocols. Measurements and data collection occurred on day 3 (8 of 20 patients) or day 4 (12 of 20 patients) of ICU admission.
**Key Results:** A total of 20 patients were enrolled, of whom 65% were male. Mean age was 64.95 ± 0.9 years, mean BMI was 32.73 ± 4.5, and mean APACHE II score was 19.65 ± 5.38. Measured REE (mREE) was 1634 ± 344.4 Kcal/day, corresponding to 20.75 ± 5.41 Kcal/Kg. Predicted REE (pREE) was 1563.5 ± 247.7 Kcal/day or 20 Kcal/Kg (p = 0.543), indicating no statistically significant difference between measured and predicted values. Prescribed energy (prE) was 1155 ± 285.57 Kcal/day or 14.98 ± 4.55 Kcal/Kg, which was significantly lower than mREE (p < 0.001). There was no statistical difference between 70% of mREE and prE (p = 0.89), indicating that prescribed energy approximated 70% of measured needs. Recommended protein needs were 72.25 ± 15.69 g/day, while prescribed protein was 54.38 ± 8.77 g/day (p < 0.001), representing a significant deficit.
**Clinical Implications:** During the acute phase of critical COVID-19 illness, patients in this cohort were normocaloric, with measured REE closely matching ESPEN-predicted values. However, prescribed energy and protein were significantly lower than both measured and recommended amounts. The prescribed energy approximated 70% of measured REE, which aligns with ESPEN guideline recommendations for hypocaloric feeding during the early days of critical illness. These findings suggest that current local protocols are being followed appropriately, but also highlight a substantial gap between measured energy expenditure and actual nutritional delivery. The protein deficit is particularly notable and may have implications for muscle wasting and recovery. Limitations include the small sample size (n=20), single-center design, and the timing of measurements (days 3–4 only), which may not capture the full trajectory of metabolic changes. Larger studies are needed to confirm these findings and to determine whether closer matching of energy and protein delivery to measured needs improves clinical outcomes in this population.