Plasma catecholamine levels were measured in 20 infants (mean age 6.0 ± 5.86 months; mean weigh 5.3 ± 1.82 Kg), undergoing correction of congenital heart defects using surface cooling (26ºC), limited cardiopulmonary bypass and circulatory arrest (15ºC). Plasma adrenaline and noradrenaline were assayed in serial arterial blood samples using cromatography and electrochemical techniques. Surface cooling produced a significant rise in adrenaline and noradrenaline: the levels of both catecholamines fell, however, during core-cooling on cardiopulmonary bypass. Following the period of circulatory arrest (23/64 min, mean 41.3 min), there was a further increase in plasma catecholamines, which persisted during rewarming. Following rewarming, plasma catecholamines remained elevated untill the end of the surgical procedure. Our data show the technique of surface cooling, limited cardiopulmonary bypass and circulatory arrest produces a major sympathoadrenal response. The biological significance of high levels of circulating catecholamines under hypothermic conditions is uncertain.
simpathoadrenal function; simpathoadrenal function; surface cooling; cardiopulmonary bypass; circulatory arrest