Controlling perioperative morbidity and mortality after lung transplantation for pulmonary hypertension.

Abstract

Lung transplantation for pulmonary hypertension now accounts for more than 18% of all transplantations performed with 1-year survival rates for primary pulmonary hypertension approximating 65%. Patients have NYHA class III or IV symptoms and typically have marked right ventricular dysfunction. Accelerated or acute decompensation can occur. A decline in status leads to a patient with severe right heart failure, hepatic dysfunction and severe malnutrition, conditions that increase perioperative morbidity and mortality. Immediate right ventricular dysfunction may be related to allograft injury with persistent elevation of pulmonary artery pressures or to intrinsic right ventricular disease; this can be supported with inotropic medications. Single-lung transplantation results in postoperative physiology that can require aggressive therapy to limit mortality. When allograft dysfunction occurs, significant hypoxemia results to a greater degree than that observed with single-lung transplantations for other diseases or following double-lung transplantation. As a result, careful donor selection for a single lung transplantation is crucial. The most common reason for prolonged ventilation is allograft reperfusion injury with ventilation-perfusion mismatching. Neuromuscular blockade can decrease oxygen utilization and improve chest wall compliance, whereas lateral positioning with the native lung down can be crucial to improving V/Q matching. Differential lung ventilation allows the application of larger quantities of positive end-expiratory pressure to the injured allograft. The use of exogenous nitrates has been advocated to reduce pulmonary vascular resistance. Nitric oxide has attractive potential benefits because it can be delivered directly to the lungs and functions to dilate the pulmonary vascular bed. All else having failed, we and others have successfully used extracorporeal membrane oxygenation to support cardiopulmonary function.