HISTAMINE-RELEASE DURING CARDIOPULMONARY BYPASS IN NEONATES AND INFANTS

Purpose: Histamine release has been previously documented in adults an d children during cardiopulmonary bypass (CPB), It has not been studie d in neonates nor during deep hypothermic circulatory arrest (DHCA), H istamine effects could explain many perioperative complications of con genital cardiac surgery such as dysrhythmias and massive oedema, There fore, documentation of histamine release in the perioperative period i s of clinical importance, The source of histamine can be determined by measurement of tryptase which is released with histamine from mast ce lls but not basophils. Methods: Blood samples for histamine and trypta se were taken before and after specific events eg, cross-clamp removal , during anaesthesia and CPB in 14 infants and seven neonates undergoi ng complex congenital heart repairs and were analysed by commercial ra dioimmunoassays, Haemodynamic variables and pre and post-op weights we re recorded to look Tor correlation between pathophysiological events and histamine release, Results: Histamine concentration decreased at t he start of bypass (0.69 to 0.38 ng.ml(-1) at five minutes, (P <.005), There were no changes associated with DHCA and a small rise with reve ntilation (P < 0.02), Histamine concentration was lower in neonates th an in infants (P < 0.05) during CPB, Plasma histamine and tryptase con centrations did not correlate, suggesting histamine release was from b asophils and not from mast cells, Haemodynamic variables did not corre late with histamine concentrations, Conclusion: There was no major his tamine release during CPB in infants and neonates, There was no relati onship between histamine concentrations and clinical variables, Histam ine released during CPB appears to come from basophils and may be a fu nction of age.