Metabolic and respiratory effects of theophylline in the preterm infant.

<bold>Background: </bold>Methylxanthines are often administered to preterm infants for the treatment of apnoea.<bold>Aims: </bold>To study the effects of theophylline on energy metabolism, physical activity, and lung mechanics in preterm infants.<bold>Methods: </bold>Indirect calorimetry was performed for six hours before and after administration of a bolus of theophylline (5 mg/kg) in 18 preterm infants while physical activity was recorded with a video camera. Lung mechanics measurements were performed at baseline and 12 and 24 hours after theophylline treatment.<bold>Results: </bold>Theophylline increased mean (SEM) energy expenditure by 15 (5) kJ/kg/day and augmented carbohydrate utilisation from 6.8 to 8.0 g/kg/day, but fat oxidation was unchanged. After theophylline treatment, preterm infants had faster respiration, lower transcutaneous CO2, and improved static respiratory compliance without increased physical activity.<bold>Conclusions: </bold>A bolus of 5 mg/kg theophylline increased energy expenditure independently of physical activity, increased carbohydrate utilisation, and improved respiratory compliance. The increased energy expenditure could be detrimental to the growth of the preterm infant. [ABSTRACT FROM AUTHOR]