Dyspnea in a lung transplant recipient.

Lung transplantation is the last resort for treatment of advanced lung disease or irreversible lung failure. The different types of acquired or genetic lung diseases that should be considered for lung transplantation include chronic obstructive pulmonary disease, emphysema, alpha-1 antitrypsin deficiency, cystic fibrosis and other causes of bronchiectasis, idiopathic pulmonary fibrosis, non-specific interstitial pneumonia, pulmonary fibrosis associated with collagen vascular disease, pulmonary arterial hypertension, sarcoidosis, lymphangioleiomyomatosis, and pulmonary Langerhans cell histiocytosis.1 Despite improvements in surgical techniques, lung preservation, immunosuppression, and management of ischemia/reperfusion injury and infections, acute and chronic allograft dysfunction and rejection remain major obstacles. The incidence and severity of acute rejection in lung transplantation exceeds all other solid-organ transplantations.2-4 Chronic allograft rejection, also called bronchiolitis obliterans syndrome, is the clinical counterpart of obliterative bronchiolitis, a fibrotic process that progressively narrows bronchiolar lumens and obstructs air flow.5 Chronic rejection or bronchiolitis obliterans syndrome affects up to 60% of patients who survive 5 years after transplantation and accounts for 30% of all deaths occurring after the third postoperative year.5 In the early era of lung transplantation, airway dehiscence was a common cause of early death.6 Systemic arterial blood supply is not restored during transplantation, so anastomotic complications are primarily attributed to ischemia of the donor bronchus.7 Additional factors that can compromise airway healing include inadequate organ preservation,7 invasive infections,8 intense immunosuppressive therapy,9 and rejection.10 Severe reperfusion edema and early rejection are independent predictors of bronchial complications.11 Standardized surgical techniques for the anastomosis help avoid bronchial complications after lung transplantation.12 Post-lung-transplantation immunosuppression therapy involves 3 classes of drugs: a calcineurin inhibitor (tacrolimus or cyclosporine), an antimetabolite (mycophenolate or azathioprine), and a glucocorticoid (prednisone). Because of the immunosuppressant therapy, prophylactic antimicrobial therapy is required to prevent opportunistic infections, including fungi, cytomegalovirus, and Pneumocystis jiroveci. Substantial post-lung-transplantation morbidity is common from medication adverse effects, because of the number of medications required and their interactions with other drugs. These adverse effects can include drug-induced methemoglobinemia, which can be identified quickly by the presence of clinical cyanosis, with normal arterial oxygen saturation measured by an arterial blood sample (SaO2).