Histamine release during cardiopulmonary bypass

Abstract

Plasma histamine concentrations were measured in 15 adult patients undergoing open-heart surgery (coronary artery bypass grafting) and in three control patients undergoing major noncardiac surgery. Plasma histamine levels rose in both open-heart and control patients in the early phase of operation before the onset of cardiopulmonary bypass (CPB). In the open-heart patients, significant elevations in plasma histamine concentrations occurred in the first 30 minutes of CPB (p < 0.05) in spite of haemodilution (median 36%). Plasma histamine changed neither by the application of X-clamp nor by its removal. No significant differences were observed between pulsatile and nonpulsatile flow of bypass perfusion. Two of the three patients who required infusion of sodium nitroprusside had high concentrations of plasma histamine (over 2ng/ml) throughout the observation period. DC shock induced an immediate response in histamine release. In the immediate post-CPB period when spontaneous circulation was resumed, the open-heart surgery patients exhibited a second rapid rise in plasma histamine, significantly higher than in the control patients (p < 0.05) in whom elevation in plasma histamine levels was not seen in the postoperative period. One of the CPB patients with persistent high histamine in the postoperative period had severe bronchospasm. Thus, in patients undergoing open-heart surgery, histamine release occurs at the onset of CPB and soon after the discontinuation of CPB. H₁ + H₂ blockade may be indicated in those at risk from histamine-mediated responses or receiving sodium nitroprusside or DC shocks.