Donor Selection

The principle criteria by which donor lungs are matched with recipients are ABO blood group compatibility and size matching (based upon the predicted total lung capacity and vital capacity; which in turn, are determined by the age, height, and gender). Donor and recipient histocompatibility antigen (HLA) matching is not currently performed.

Criteria to determine suitability of donor lungs for transplantation have traditionally been rigorous and at most 20% of otherwise suitable multiple organ donors have lungs that meet the traditional criteria for lung transplantation, Table 12.4. Most of the conditions that result in brain death (trauma, spontaneous intracerebral hemorrhage) are associated with significant pulmonary injury that precludes transplantation (lung contusion, aspiration, infection, and neurogenic pulmonary edema).

Satisfactory gas exchange is imperative for donor lungs. This can be confirmed by a partial oxygen pressure (Pa02) that is greater than 300 mmHg with a ventilator delivering a fraction of inspired oxygen (FI02) of 1.0 and 5 cmH20 positive end-expiratory pressure (PEEP). A Pa02 to FI02 ratio of 300 or greater provides adequate evidence of satisfactory gas exchange. A donor chest x-ray must reveal clear lung fields. Bronchoscopic evidence of aspiration or frank pus in the airway is a definitive contraindication to transplantation.

A strategy that has been employed to overcome the shortage of donor lungs is the use of "marginal " lungs (defined as donor lungs that do not meet all of the traditional criteria). Relaxation of the normally strict criteria has been shown not to adversely affect outcome under carefully selected circumstances.4-10 A minor degree of parenchymal infiltration can be accepted in a donor who is being used for a bilateral lung transplant. Judicious use of the contralateral lungs from donors with unsatisfactory gas exchange and radiographic or bronchoscopic findings confined to one lung also helps to increase the pool of donor lungs.

Other strategies to increase the donor pool include the use of living related donors for lobar transplantation and pulmonary bipartitioning.11,12 Although innovative and exciting, these procedures are unlikely to have any meaningful impact in the overall shortage of lung allografts.

Crucial issues to successful management of the potential lung donor once brain death is declared are pulmonary toilet and fluid management. Because of its exposure to the external environment, the donor lung is at greater risk of infection than other organs. Measures such as frequent positioning change, chest physiotherapy and sterile endotracheal suctioning are recommended to protect the potential lung allografts.

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