Proefschrift Kerklaan

Use of indirect calorimetry to detect overfeeding

METHODS

Neonates and children up to the age of 18 years admitted to our level III multidisciplinary PICU were consecutively included in the study when they met the criteria for indirect calorimetric measurements: mechanical ventilation with a Servo ventilator (Siemens-Elema, Solna, Sweden); FiO 2 <0.6, tube leakage <10% and hemodynamic stable condition (blood pressure and heart rate within 2 standard deviation (SD) of age-related values). The institutional review board of the Erasmus MC approved the study protocol, and written parental informed consent was obtained before children entered the study. Data, including age, sex, weight, primary diagnosis, surgical status, days on mechanical ventilation, length of ICU stay, route of nutritional support, and energy and macronutrient intake were recorded. The severity of illness on admission was assessed by the Pediatric Risk of Mortality score (PRISM) 31 . Nutritional status on admission was defined by weight for age (WFA) SD-scores using Dutch Growth Standards 32 ; children were categorized as underweight if their WFA SD-score was <-2. Indirect calorimetrymeasurementswereperformedas soonaspossibleafter admission.Oxygen consumption (VO 2 ) and carbon dioxide production (VCO 2 ), standardized for temperature, barometric pressure, and humidity were measured for at least 2 hours using the Deltatrac® (Datex Division Instrumentarium, Helsinki, Finland) metabolic monitor. Measured REE (mREE) was calculated with the modified Weir formula 33 . The properties of the Deltatrac® metabolic monitor have been described previously 34 . The RQ was calculated from the measured VO 2 and VCO 2 levels 24 . Children were fed enterally and/or parenterally according to the local feeding protocol 25 and the judgement of the attending physician. A glucose infusion was provided during the first 12 to 24 hours after admission aimed at a carbohydrate intake of 4 to 6mg/kg/min (children<30kg) or 2 to 4 mg/kg/min (>30kg) 35,36 . Enteral nutrition (EN), consisting of human milk or standard formula, was started as soon as possible in all patients, either continuously or intermittently through a postpyloric or nasogastric tube. PN was started within 48 hours after admission in case of insufficient EN, either by peripheral infusion or by central venous access. Fluid and electrolyte intakes were adjusted to individual requirements. Energy goals for EN were based on the body weight-based Schofield equation 37 on the first day of admission and on the Recommended Dietary Allowances for the subsequent length of stay (Dietary Reference Intake: energy, protein and digestible carbohydrates, 2001, Health Council of the Netherlands: The Hague). Parenteral energy goals were based on the weight-based guidelines of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) throughout PICU stay 38 . Actual total daily intake of energy, carbohydrate, protein and fat were derived from patient records on the day of calorimetry.

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