Alveolar epithelial function is better preserved in lungs from nonheart-beating donors compared with heartbeating donors

Objective

Intact function of the alveolar epithelium is of critical importance to resolve reperfusion edema after lung transplantation. The mechanism, known as alveolar liquid clearance (ALC), can be stimulated by β-adrenergic agents such as terbutaline. ALC in lung grafts and the effect of terbutaline was evaluated in an isolated reperfusion model comparing donor lung injury following brain death in the heart-beating donor (HBD) versus 1 hour of warm ischemia in the nonheart-beating donor (NHBD).

Methods

Pigs were divided into six groups (n = 3/group). In HBD and HBD-T, brain death was induced by intracranial balloon inflation. In control animals, CONT and CONT-T, the balloon was not inflated. In NHBD and NHBD-T, cardiac arrest was induced by myocardial fibrillation. After 5 hours of mechanical ventilation, lungs in HBD, HBD-T, CONT and CONT-T were flushed. In NHBD and NHBD-T, unflushed grafts were explanted after 1 hour of warm ischemia and 4 hour of in-situ topical cooling. Grafts in all groups were evaluated for 2 hours in an isolated ventilation and reperfusion model. At the start of reperfusion, 100 ml iso-oncotic albumin solution was instilled in all lungs and mixed with 10^-3 M terbutaline in HBD-T, CONT-T and NHBD-T to stimulate ALC. The ALC (percentage of alveolar fluid resorbed per hour) was calculated by comparing the initial and final protein concentrations in the instillate with the formula: 100 × (1 - initial protein / final protein) / 2.

Results

See Table 1.

Table 1

Conclusion

ALC during isolated reperfusion is decreased following brain death in HBD but not in NHBD. The effect of terbutaline on ALC was mostly apparent in HBD. These data further support the use of NHBD in lung transplantation. Terbutaline may be a promising tool to stimulate epithelial function in lungs from HBD and to resolve ischemia-reperfusion injury.