The effects of inhaled nitric oxide after lung transplantation

Primary graft failure (PGF) is one of the major complications that occurs immediately following lung transplantation and greatly contributes to increased morbidity and mortality. The incidence of PGF is correlated with a marked decline in endogenous nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) levels. Therefore, the administration of NO during lung transplantation has been proposed as a possible therapeutic treatment to prevent or attenuate PGF pathogenesis. Despite the initial positive results of experimental and uncontrolled clinical trials, recent randomized clinical trials do not support the prophylactic administration of inhaled nitric oxide (iNO) for the prevention of PGF following lung transplantation under the conditions tested. Nonetheless, there is evidence that iNO administration during PGF can improve oxygenation and reduce pulmonary hypertension without altering systemic vascular resistance. This suggests that iNO may prevent the need for extracorporeal membrane oxygenation (ECMO) during the hypoxic phase of PGF. During the intraoperative phase of transplantation, one-lung ventilation (OLV) and pulmonary artery clamping usually increase PVR, causing decreased right ventricular function and hemodynamic instability. The administration of iNO during these lung transplant procedures could decrease right ventricular dysfunction by reducing PVR and help to avoid the use of cardiopulmonary bypass.