When Should Indirect Calorimetry Be Repeated To Measure Resting Energy Expenditure In Critically Ill Covid-19 Patients?

Rationale: Indirect calorimetry (IC) guided nutrition can reduce the short-term mortality and other complications for patients in the ICU. Clinical guidance to know when to repeat IC to measure resting energy expenditure (REE) remains unknown. The aim of this study is to evaluate which factors are associated with at least a 10% change in REE compared to the previous measurement and thus warrant a new IC in intubated Covid-19 patients. Methods: PCR confirmed Covid-19 patients, who needed airway support in ICU and had at least two IC measurements during their stay, were included from the four waves (April 2020 – February 2022) and retrospectively analyzed. The relation of absolute changes in temperature, RASS scores closest to the time of IC, days since last IC, inflammatory lab values and ventilator settings with the odds of a 10% change in REE were assessed using generalized estimating equations, accounting for the clustered data. Results: A total of 111 IC's from 34 patients (27, 79% male)were analysed. The number of IC's per patient ranged from 2 to 9 (median 3). The median (Q1;Q3) age at baseline was 63.4 (57.4;67.8) years at baseline with a mean (SD) BMI of 30.8 (5.3) kg/m2. The median ventilator and ICU day for the first IC measurement were respectively 5.5 (1.2;10) and 6.0 (3.2;10.7).The median number of days between consecutive IC measurements was 7.0(4.0;9.0). The only significant factor associated with a 10% change in REE was a change in RASS score (OR 0.66, 95% CI 0.44;0.99). Changes in white blood cell count, CRP, body temperature, FiO2 and minute volume do not contribute significantly to REE change. Conclusion: Significant changes in RASS scores in ventilated Covid-19 patients should prompt clinicians to re-evaluate the caloric needs of their patients by repeating an indirect calorimetry Disclosure of Interest: None declared