Histamine release in paediatric cardiopulmonary bypass--a possible role in the capillary leak syndrome.

Recent studies have reported pathologically elevated plasma histamine levels in adult patients during and after open heart surgery. In paediatric practice, the increased use of donor-blood primes might be expected to produce even greater rises in the histamine levels, by creating histamine release in the prime before initial perfusion commences. The present study covered 40 arbitrarily chosen paediatric cases. Pathologically elevated plasma histamine levels (greater than 1 ng/ml) were found in the prime of 26 out of 37 cases (73%). Histamine levels were substantially higher than levels encountered in previously reported studies, and massively elevated prime histamine levels (greater than 80 ng/ml) were encountered in 9 out of the 40 cases (22%). These results suggest that in conventional paediatric cardiac surgical practice, the prime content of histamine is markedly elevated in the majority of patients. The inevitable delivery of this prime histamine load at the onset of perfusion might be expected to produce systemic pathological effects.