Effect of caffeine on oxygen consumption and metabolic rate in very low birth weight infants with idiopathic apnea

Objective. Methylxanthines are among the most commonly prescribed drugs in neonatal intensive care. This study evaluates the effect of caffeine on oxygen consumption and metabolic rate in premature infants with idiopathic apnea. Methods. Eighteen preterm infants at gestational ages from 28 to 33 weeks and birth weights of 890 to 1680 g were enrolled in the study. Nine preterm infants received caffeine therapy, and 9 served as a control group. Oxygen consumption and energy expenditure were examined before, during, and after caffeine treatment. Results. Oxygen consumption increased significantly from 7.0 +/- 0.9 before caffeine to 8.8 +/- 0.7 mL/kg/min after 48 hours of caffeine therapy, and energy expenditure increased from 2.1 +/- 0.3 to 3.0 +/- 0.2 kcal/kg/hour. During the observation period of 4 weeks of caffeine treatment, oxygen consumption increased significantly in the caffeine group compared with the control patients. In the caffeine group, a lower environmental temperature was sufficient to maintain a normal body temperature. With similar caloric intake in both groups during the study period, daily weight gain in the control group was significantly higher (21 +/- 4 vs 42 +/- 2 g/d). None of the other parameters recorded changed during caffeine therapy. Conclusion. Long-term administration of caffeine in preterm infants is associated with an increase in oxygen consumption and with a reduction of weight gain. This may have implications for clinical practice as nutritional regimens need to be adjusted during this therapy.