Successful Repair of Donation After Circulatory Death Lungs With Large Pulmonary Embolus Using the Lung Organ Care System for Ex Vivo Thrombolysis and Subsequent Clinical Transplantation

The 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 PRESENTATION A 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 Pao2/Fio2 of less than 350 mm Hg before withdrawal of life-sustaining 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 Pao2/Fio2 of 202 and continued to improve during ex vivo thrombolysis to a final Pao2/Fio2 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 H2O). 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.Figure 1: A, Anterior-posterior chest radiographs of donor lungs after Lung OCS perfusion and transplantation into recipient at T0. B, Incidence of postoperative PGD as assessed using International Society for Heart and Lung Transplantation consensus. Chest x-rays was performed at respective posttransplantation times for the assessment of radiograph infiltrates consistent with pulmonary edema. Pao2/Fio2 indicates partial pressure of oxygen ratio; T0, 0 hour after transplantation; T24, 24 hours after transplantation; T48, 48 hours after transplantation; T72, 72 hours after transplantation.DISCUSSION The use of a stationary ex vivo lung platform and treatment of donor lungs with PE has been described once,3 and PE found in 38% of donor lungs is associated with worse PGD scores after transplantation.4 This is a unique report of a DCD donor with PE and subsequent successful ex vivo thrombolysis and assessment using the portable Lung OCS followed by clinical transplantation. This case differs from the previously described ex vivo thrombolysis3 as PVR and PA pressure at full cardiac output could not be measured, yet improvement in oxygenation on the Lung OCS allowed for objective evidence of acceptable lung function for transplantation. This case highlights some of the differences in the currently available technologies for ex vivo lung perfusion5 and describes the potential for targeted therapy using current ex vivo lung perfusion technologies to correct for deficiencies in marginal DCD donor lungs before transplantation. ACKNOWLEDGMENTS The authors thank the Human Organ Procurement and Exchange (HOPE) Program for their support.

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