[Changes of exhaled nitrogen-monoxide concentration in acute ischemia-reperfusion injury of the lung]

Nitric oxide (NO) plays an important role in both the physiological control of the pulmonary vascular bed and in the pathophysiology of several lung diseases. Though our knowledge regarding NO has became wider several aspects are still a matter of debate. The technical developments allowing direct measurements of NO in the expired air have provided an opportunity to evaluate NO production and consumption in the clinical setting and exhaled NO has become a diagnostic and monitoring tool in acute and chronic lung diseases.

The aim of our study was to evaluate the severity of different levels of ischaemia-reperfusion related lung injury by measuring nitric oxide in the exhaled air. After presenting our data regarding exhaled NO in ischaemia-reperfusion related acute lung injury associated with cardiothoracic surgery we discuss the physiology of exhaled NO and the technical aspects of measuring NO in the expired breath.

Comparing basal and GTN-induced exhaled NO data after two types of heart and lung surgery--routine open-heart surgery utilizing CPB and lung transplantation--we studied the effects of different levels of lung ischaemia on NO production.

Following transient and incomplete lung ischaemia in the clinical setting of routine cardiac surgery utilizing cardiopulmonary bypass (CPB) both the airway epithelial and the vascular endothelial function remained preserved. However, prolonged and complete lung ischaemia during lung transplantation was associated with severe dysfunction resulted in a marked reduction of both the endogen and the induced levels of exhaled NO.