Critically ill children in the pediatric intensive care unit (PICU) differ in their energy needs from healthy children in terms of underlying metabolism and growth, comorbidities, and preexisting energy reserve, and this makes it difficult to estimate energy needs in these patients. Estimates of energy expenditure using available standard equations are often unreliable. True energy needs can be determined only by measuring energy expenditure with indirect calorimetry (IC). This preliminary study determined how many PICU patients would be candidates for IC, based on current recommendations by the American Society for Parenteral and Enteral Nutrition. IntroductionCritically ill children, especially infants, in the pediatric intensive care unit (PICU) are at high risk of developing nutrition deficiencies, altered nutrition status, and anthropometric changes that may lead to increased morbidity.1,2 Acute injury, inflammation, surgery, or sepsis markedly alters energy needs by inducing hyper-and hypometabolic conditions 3-5 that may be present in a single patient at different time points in the continuum of care. It is essential to provide the appropriate energy, substrate distribution, and micronutrients necessary to support the ongoing metabolic and stress response to avoid the loss of critical lean body mass and worsening of any existing nutrient deficiencies. AbstractBackground: Critically ill children differ in their energy needs from healthy children in terms of underlying metabolic derangement, comorbidities, energy reserve, and response to illness. This study determined how many pediatric intensive care unit (PICU) patients were candidates for indirect calorimetry (IC), per American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) recommendations. Methods: Admission diagnosis, demographics, type/amount of nutrition support, length of intensive care unit/hospital stay were collected. Patients were classified as candidates for IC per A.S.P.E.N. guidelines. Results: Mean (SD) age of patients (n = 150) was 6.7 (5.6) years, with PICU length of stay of 3.9 (5.3) days. IC was indicated in 72.0% (108/150) of patients during PICU days 1-7. Patients with miscellaneous (50%), neurological (73%), respiratory (81%), sepsis (83%), and oncology (100%) diagnoses were candidates for IC. Underweight/overweight/obese (32.4%), hypermetabolism (26.4%), and not meeting nutrition goals (13.7%) were the most frequent indications for IC (χ