Indirect calorimetry in mechanically ventilated children: a new technique that overcomes the problem of endotracheal tube leak. 
To develop indirect calorimetry to enable measurement of energy expenditure in mechanically ventilated children and to assess the effect of endotracheal tube leak on the accuracy of indirect calorimetry measurements.  Prospective, observational study, using a convenience sample.  Tertiary pediatric intensive care unit in a university-associated children's hospital.  Eighteen patients, 3 months to 10 yrs of age, with various diagnoses, and requiring mechanical ventilation.  Patients were intubated and received routine intensive care treatment.  Energy expenditure and respiratory quotient were measured using a new modification to the technique of indirect calorimetry, which includes an assessment of any expired gas lost around the endotracheal tube.  Mean energy expenditure was 97% of predicted energy expenditure, but there was great variability between patients, and energy expenditure could not be estimated reliably from predictive equations.  The amount of expired gas lost because of gas leak around the endotracheal tube was often a clinically important proportion of total expired gas, and this lost gas could not be predicted by audible endotracheal tube leak.  Measurement of energy expenditure by indirect calorimetry may be useful in the nutritional management of critically ill children.  Results may be inaccurate if the gas lost because of leak around uncuffed endotracheal tubes is not taken into account.