Does prophylactic inhaled nitric oxide reduce morbidity and mortality after lung transplantation?

Abstract

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was does prophylactic inhaled nitric oxide (NO) reduce morbidity and mortality after lung transplantation? Altogether 232 papers were found using the reported search, of which six represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. Primary graft dysfunction and failure are serious complications in the first few days following lung transplantation. These phenomena are characterised by bilateral infiltrates on chest radiographs, reduced lung compliance and increased FiO(2) requirements and alveolar-arterial gradients; thus necessitating prolonged mechanical ventilation and often leading to significant mortality. The process known as ischaemic-reperfusion injury is thought to underlie primary graft failure. The studies conducted examining the role of inhaled NO in preventing morbidity and mortality after orthotropic lung transplant tend to focus on potential reductions in the incidence of ischaemic-reperfusion injury as the determinant of clinical outcomes. The majority of these are unfortunately non-randomised and/or uncontrolled studies. All the studies discussed, including the two prospective randomised controlled trials, suffer from small sample sizes. Nonetheless, despite their limitations, there are currently, no randomised controlled studies that demonstrate a reduction in morbidity [time to extubation, length of intensive care unit (ICU) or hospital stay] or mortality. As such it is difficult to currently, recommend the routine use of prophylactic inhaled NO in lung transplant surgery. Further studies may outline a benefit in certain types of surgeries, e.g. single-lung transplants or double-lung requiring cardiopulmonary bypass.