Nitroglycerin and sodium nitroprusside: potential contributors to postoperative bleeding?

Postoperative bleeding is common in patients undergoing cardiac surgery with cardiopulmonary bypass. Most cases of severe postoperative bleeding not due to incomplete surgical hemostasis are related to acquired transient platelet dysfunction mediated by platelet activation during contact with the synthetic surfaces of the cardiopulmonary bypass equipment. Antihypertensive agents nitroglycerin and sodium nitroprusside have been shown to have platelet inhibitory properties, yet the clinical consequence in terms of postoperative bleeding has been little studied. Knowing that cardiopulmonary bypass causes platelet dysfunction, it is prudent for physicians to be aware of the additional platelet inhibition caused by these commonly used antihypertensive agents.