Dynamics of Nitroglycerin-induced Exhaled Nitric Oxide After Lung Transplantation: Evidence of Pulmonary Microvascular Injury?

Partitioning of exhaled NO in ventilated patients undergoing cardiac surgery

The change in exhaled NO after cardio-pulmonary bypass remains controversial. The aims were to determine whether exhaled NO sources (alveolar or bronchial) are modified after bypass, and whether mechanical ventilation (MV) settings during bypass modify exhaled NO changes. Thirty-two patients were divided into three groups: without MV during bypass and positive end-expiratory pressure (PEEP) (n=12), dead space MV without PEEP (n=10) and dead space MV with PEEP (n=10). Alveolar NO concentration and bronchial NO flux were calculated before and 1h after surgery using a two-compartment model of NO exchange developed in spontaneous breathing patients. Whereas a significant decrease in bronchial NO was found after bypass in the two groups without PEEP during bypass, this decrease was not observed in patients with dead space ventilation with PEEP. Alveolar NO was not significantly modified whatever the ventilation settings. In conclusion, the impairment of bronchial NO seemed related to airway closure since dead space mechanical ventilation with PEEP prevented its decrease.

Anesthetic Considerations for Lung Transplantation

Lung transplantation is the definitive treatment for end-stage lung disease. The number of lung transplantations performed is limited by the number of donors available and is far outnumbered by the potential recipients on the waiting list. Advances in surgical methods, organ preservation, and immunosuppression have decreased the morbidity and mortality associated with this procedure during the last few decades. Specific anesthetic concerns are associated with lung transplantation, including careful preoperative assessment of pulmonary and cardiac function, adequate venous access and monitors, and ventilation techniques, such as 1-lung ventilation and lung-protective strategies to decrease the risks of reperfusion injury, barotrauma, and re-expansion pulmonary edema. Intraoperative transesophageal echocardiography, cardiopulmonary bypass, and inhaled nitric oxide can also be important tools for the anesthesiologist to optimize patient care during this challenging procedure.