How long can we preserve the pulmonary graft inside the nonheart-beating donor?

Background The use of lungs from nonheart-beating donors (NHBD) might significantly alleviate the organ shortage. Extending the preharvest interval in NHBD would facilitate distant organ retrieval. We hypothesized that prolonged topical cooling inside NHBD after 60 minutes of initial warm ischemia would not affect the pulmonary graft. Methods Domestic pigs were anesthetized and divided into three groups (n = 6 in each group). In the control group (HBD), lungs were flushed, explanted, and further stored in low potassium dextran solution (4°C) for 4 hours. In the two study groups pigs were sacrificed by myocardial fibrillation and left untouched for 1 hour. Chest drains were then inserted for topical lung cooling (6°C) for 3 hours (NHBD-TC3) or 6 hours (NHBD-TC6). The left lung in all groups was then prepared for evaluation. In an isolated circuit lungs were ventilated and reperfused through the pulmonary artery. Hemodynamic, aerodynamic, and oxygenation variables were measured 35 minutes after onset of controlled reperfusion. Wet-to-dry weight ratio was calculated. Results No significant differences were observed among the three groups in pulmonary vascular resistance (p = 0.38), mean airway pressure (p = 0.39), oxygenation index (p = 0.62), and wet-to-dry weight ratio (p = 0.09). Conclusions These data confirm that 1 hour of warm ischemia does not affect the pulmonary graft from NHBD compared with HBD. The preharvest interval can be safely extended up to 7 hours postmortem by additional topical cooling of the graft inside the cadaver. This technique may facilitate distant organ retrieval in NHBD.