Background: Recent studies have suggested that preservation of donor lungs with inflation provides better pulmonary function after transplantation, but hyperinflation of pulmonary grafts during storage increases reperfusion pulmonary edema. To elucidate the optimal inflation volume during the preservation period, and the possible role of barotrauma in lung injury after atelectatic storage, we examined the effects of inflation volume and reinflation protocols in hypothermically preserved rat lungs.
Methods: Adult rat lung blocks were preserved at 4 degrees C for 18 hours at various levels of inflation. Static pulmonary compliance was measured and compared before and after preservation. The hemodynamics and gas exchange function of optimally inflated lungs were then compared with lungs preserved atelectatically in a rat paracorporeal reperfusion model.
Results: We found that the optimal level of inflation for preservation is 50% of total lung capacity (TLC). Lungs stored atelectatically or inflated to 25% of TLC showed deterioration of postpreservation lung compliance, whereas air leaks were observed in most of the lungs preserved with inflation to 75% or 100% of TLC. The hemodynamics and gas exchange function in lungs preserved with inflation at 50% of TLC were significantly better than that of atelectatically preserved lungs. A gentle reexpansion of atelectatically stored lungs did not prevent the deterioration of pulmonary function.
Conclusion: Donor lungs should be preserved at an optimal inflation volume, and mechanisms other than barotrauma after atelectatic storage may be responsible for postpreservation and postreperfusion lung injury.