T he boundary of marginal lung utilization is expanding with the development of ex vivo lung perfusion to improve donor lung function. 1 We report the use of the Transmedics Lung Organ Care System (OCS) to lyse pulmonary embolus (PE) from a set of donation after circulatory death (DCD) lungs with subsequent clinical transplantation.
CASE PRESENTATIONA 29-year-old woman who presented with Medical Research Council 5 dyspnea resulting from end-stage respiratory disease secondary to cystic fibrosis was placed on the lung transplant waiting list. Medical history was significant for chronic upper lobar collapse and widespread bronchiectasis resulting in hyperinflation of the lower lobes, with a lung ventilation perfusion (V/Q) split of 30% left lung and 70% right lung.The patient underwent bilateral lung transplantation without cardiopulmonary bypass. Lungs were procured from a DCD donor with anoxic brain injury caused by PE with unsuccessful thrombolysis during cardiac arrest and resuscitation. Subsequent computed tomographic scan revealed peripheral residual PE with borderline oxygenation PaO 2 / FIO 2 of less than 350 mm Hg before withdrawal of lifesustaining treatment. The warm ischemic time was 27 minutes. Gross evidence of PE in distal pulmonary arteries (PAs) was mechanically removed and 5 mg of Alteplase was added to the Lung OCS perfusion circuit for ongoing ex vivo thrombolysis of residual PE over 2.5 hours. Pulmonary vascular resistance (PVR) of 190 to 230 dyne · s · cm −5 was not significantly elevated during perfusion in part owing to the rate of flow being 40% of cardiac output. The device is not suited for flow at 100% cardiac output; thus, the true PVR is unable to be determined. Thus, we rely on the oxygenation of the lungs, which was marginal based on the initial PaO 2 /FIO 2 of 202 and continued to improve during ex vivo thrombolysis to a final PaO 2 /FIO 2 of 486. The improvement in oxygenation indicated a decrease in V/Q mismatch correlating to a decrease in embolic burden, thus providing evidence that the lungs were suitable for transplantation. During Lung OCS perfusion of 300 and 353 minutes for the left and the right lungs, respectively, peak airway pressure remained stable (12-15 mm Hg), PA pressures were low (approximately 6 mm Hg), whereas dynamic compliance improved significantly (42-400 mL/cm H 2 O). The patient was transferred to the intensive care unit, and the chest radiograph after transplantation was clear ( Figure 1A). Pulmonary artery catheter showed low PVR (151-181 dyne · s · cm −5 ) and PA pressures (26/17-23/9 mm Hg). Her primary graft dysfunction (PGD) score improved within the first 24 hours after transplantation ( Figure 1B), 2 and she was extubated on postoperative day 1 and transferred to the ward on postoperative day 5. She had an uneventful postoperative course and was discharged. Her forced vital capacity was 4.18 L, and her forced expiratory volume was 3.53 L at 4 months after discharge.
DISCUSSIONThe use of a stationary ex vivo lung platform and treatment of donor lung...