EFFECT OF AMINOPHYLLINE ON CEREBRAL HEMODYNAMICS AND OXIDATIVE-METABOLISM IN PREMATURE-INFANTS

The effect of aminophylline on cerebral blood volume and oxidative met abolism in newborn infants was investigated with near infrared spectro scopy (NIRS). Thirteen mechanically ventilated premature infants who r eceived aminophylline to facilitate weaning from the respirator were s elected. Gestational age ranged between 26 and 34 weeks, postnatal age between 1 and 7 days and birth weight between 760 and 2300 g. A bolus of 6 mg aminophylline/kg body weight was infused within 2 min. NIRS w as performed continuously across the head to monitor changes in cerebr al blood volume and cytochrome c oxidase. Heart rate, transcutaneous c arbon dioxide tension (tcpCO(2)) and arterial haemoglobin oxygen satur ation (SO2) were recorded simultaneously. The infusion of aminophyllin e was associated with an increase in heart rate (median 12, interquart ile range 5-20 beats per min, P = 0.0004) and a drop in tcpCO(2) (medi an -0.4, interquartile range -0.1 to -0.5 kPa, P = 0.015). Oxygen satu ration remained stable (+/- 3%). A decrease in cerebral blood volume w as measured with NIRS in 9/13 patients (median -0.15 ml/100g brain tis sue, interquartile range +0.08 to -0.28, P = 0.10). Oxidized cytochrom e c oxidase decreased in 11/13 patients (median -0.27 mu mol/l, interq uartile range -0.19 to -0.44, P = 0.01). Our findings demonstrate an i mmediate step-response of heart rate and tcpCO(2) to aminophylline in premature infants. The simultaneous reduction of cytochrome c oxidase in the brain cannot be explained as a consequence of changes in tcpCO( 2) or changes in cerebral blood volume. We therefore speculate that am inophylline interferes directly with cerebral metabolism.