Metabolic and respiratory effects of theophylline in the preterm infant

Background-Methylxanthines are often administered to preterm infants for th e treatment of apnoea. Aims-To study the effects of theophylline on energy metabolism, physical ac tivity, and lung mechanics in preterm infants. Methods-Indirect calorimetry was performed for six hours before and after a dministration of a bolus of theophylline (5 mg/kg) in 18 preterm infants wh ile physical activity was recorded with a video camera. Lung mechanics meas urements were performed at baseline and 12 and 24 hours after theophylline treatment. Results-Theophylline increased mean (SEM) energy expenditure by 15 (5) kJ/k g/ 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 resp iratory compliance without increased physical activity. Conclusions-A bolus of 5 mg/kg theophylline increased energy expenditure in dependently of physical activity, increased carbohydrate utilisation, and i mproved respiratory compliance. The increased energy expenditure could be d etrimental to the growth of the preterm infant.