Plasma catecholamines after endotracheal administration of adrenaline during postnatal resuscitation.

To analyse the degradation of adrenaline after cardiopulmonary resuscitation of preterm neonates, free and sulphoconjugated adrenaline, noradrenaline, and dopamine were determined in 31 preterm neonates by a radioenzymatic method. Nine of the neonates received a high dose (250 micrograms/kg) of endotracheally administered adrenaline (1:1000); three of them had more than one dose of adrenaline. With the exception of sulphoconjugated dopamine, the free and sulphoconjugated catecholamine concentrations in preterm infants treated with adrenaline initially exceeded those in the untreated group. The concentrations decreased to the same range about two hours after birth. Free and sulphoconjugated adrenaline concentrations remained significantly increased in the adrenaline treated group, however, indicating a plateau effect. The correlation between free adrenaline and noradrenaline concentrations with their respective sulphoconjugated concentrations was highly significant. It is concluded that free catecholamines are rapidly degraded by sulphoconjugation in preterm neonates.