The effect of hypothermic cardiopulmonary bypass on plasma adrenomedullin in adult cardiac surgical patients

Cardiopulmonary bypass (CPB) can evoke a systemic inflammatory response, which is accompanied by an increase in plasma cytokines that may stimulate the production of adrenomedullin (AM), a potent vasodilator peptide. This study was undertaken to investigate whether CPB influenced plasma AM concentration in 10 patients undergoing cardiac surgical procedures. We found that the plasma AM concentration increased significantly after the commencement of CPB, with the greatest increase observed at weaning from bypass (P < 0.01). After CPB, plasma AM concentration declined but still exceeded baseline significantly 24 h postoperatively. The increase in the plasma AM concentration at weaning from CPB correlated significantly with aortic cross-clamp time (I = 0.74, P < 0.05). The authors conclude that the secretion of AM into circulation is augmented by CPB in patients undergoing cardiac surgery, which suggests a possible role of AM in cardiovascular regulation during and after surgery with CPB.