Nitric oxide (NO) was proclaimed the 1992 “molecule of the year” by Culotta in Science magazine because of its importance in neuroscience, physiology and immunology. Inhaled NO has been in clinical use for over 35 years to decrease pulmonary hypertension and improve oxygenation. Over the last 20 years there has been much research to understand the role of nitric oxide on cell surface receptors, mitochondria, and intracellular processes which involve calcium and superoxide radicals. This research has shown that, irrespective of the cause, NO has a major role in the systemic inflammatory response syndrome (SIRS) and ischaemia-reperfusion injury (IRI).1 More recent clinical research has focused on NO use in patients undergoing cardiopulmonary bypass and receiving extracorporeal life support, with some centres incorporating nitric oxide into sweep gas as part of routine practice. This article reviews NO pathways in humans, the biological effects of NO, the interplay between nitric oxide and red blood cells, and animal and human studies on the effects of exogenously administered NO.
