Maintenance of brain-dead donors for lung transplantation, donor selection, evaluation and ex vivo protection 3.1 Maintenance of brain-dead donors 3.1.1 Routine treatment A series of pathophysiological changes after brain death are treated accordingly to ensure effective organ perfusion and oxygen supply, maintain stable blood pressure and normal water, electrolyte, acid-base balance, bring the organism close to physiological state, and ensure that the structure and function of the lung are not further damaged. . 3.1.2 Use of lung protection strategy Protective ventilation strategy: target tidal volume 6-8 mL/kg, positive end-expiratory pressure (PEEP) 8-10 cmH2O, and the rest of parameters can be adjusted according to the results of monitoring blood gas analysis to improve donor oxygenation and avoid donor atelectasis or infection. In all potential lung donors, bronchoscopy is routinely performed to remove sputum and blood clots as well as other secretions from the airway. Maintain hemodynamic stability: stricter fluid management measures to maintain as much as possible an in/out balance or a mild negative balance. Reasonable application of vasoactive drugs to control blood pressure and ensure perfusion of other vital organs. Hormone therapy: brain-dead patients may have deficiency of important hormones in the body. For cortisol deficiency, high-dose methylprednisolone (15 mg/kg) can be used; for patients with uremia, desmopressin or posterior pituitary hormone can be used to control it, and if necessary, thyroid hormone supplementation is needed, etc. 3.2 Donor selection and evaluation Donor evaluation [8] includes age, blood group, HLA typing, type of death, chest imaging, arterial blood gas analysis, bronchoscopy for pathogenesis and direct visual inspection after donor lung excision, ischemic time, presence of recent lung infection, presence of pulmonary edema, presence of aspiration injury, history of smoking, presence of chest tumors, presence of infectious diseases, presence of If there is a serious shortage of ideal donor lung, the use of marginal donor can increase the source of donor, but it is prone to severe primary graft dysfunction (PGD) and high early mortality after surgery, and its application should be more cautious. If a marginal donor is used, an ex vivo repair technique, normothermic EVLP, is recommended as a donor lung assessment and preoperative pretreatment, and those with significant improvement after ex vivo repair can be used for transplantation [9]. To improve the comprehensive donor assessment, the OtoLungDonorScore [10] or the University of Minnesota donor lung scoring criteria [11] can be used. 3.3 Acquisition of donor organs for lung transplantation [8] After cardiac arrest and lung washout are completed, the heart and lungs are sequentially removed. The lung is completely dissected free and the trachea is clamped closed with the lung in an inflated state to terminate mechanical ventilation. If the donor lung is to undergo high-altitude airlift and care must be taken for barotrauma at altitude, partial inflation is given. When obtaining the donor heart at the same time, care is taken to obtain the donor lung with sufficient left atrial sleeve preserved to facilitate the anastomosis of the atrial sleeve during surgery. 3.4 Donor perfusion and isolation protection [8] The main objective is to reduce the incidence of ischemia-reperfusion injury while ultimately avoiding graft loss of function. This is generally addressed by 3 approaches: (1) rational estimation and handling of the donor lung; (2) optimal lung preservation and perfusion techniques; and (3) appropriate prevention and treatment of ischemia-reperfusion injury. For donor lung acquisition, the general recommendation is a thermal ischemia time <35 min, including <20 min for cardiac death donors, pulmonary artery perfusion pressure of 10-15 mmHg, perfusion volume of 60 mL/kg, retrograde perfusion of 250 mL per pulmonary vein, perfusate temperature of 4°C to 8°C, respiratory inhalation oxygen concentration (FiO2) of 50% at acquisition, PEEP of 5 cmH2O. Pressure <20cmH2O, tidal volume 6-8mL/kg, the isolated donor lung needs to be maintained at approximately 50% inflation and expansion. For preservation of ex vivo donor lung, static cold preservation based on extracellular fluid (Perfadex fluid, RLPD fluid, etc.) at 4°C to 8°C is recommended. Its cold ischemia time is usually no more than 10-12h.