OPTIMAL INFLATION VOLUME FOR HYPOTHERMIC PRESERVATION OF RAT LUNGS

Background: Recent studies have suggested that preservation of donor l ungs with inflation provides better pulmonary function after transplan tation, but hyperinflation of pulmonary grafts during storage increase s reperfusion pulmonary edema. To elucidate the optimal inflation volu me 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 preserve d rat lungs. Methods: Adult rat lung blocks were preserved at 4 degree s C for 18 hours at various levels of inflation. Static pulmonary comp liance was measured and compared before and after preservation. The he modynamics and gas exchange function of optimally inflated lungs were then compared with lungs preserved atelectatically in a rat paracorpor eal reperfusion model. Results: We found that the optimal level of inf lation for preservation is 50% of total lung capacity (TLC). Lungs sto red atelectatically or inflated to 25% of TLC showed deterioration of postpreservation lung compliance, whereas air leaks were observed in m ost of the lungs preserved with inflation to 75% or 100% of TLC. The h emodynamics and gas exchange function in lungs preserved with inflatio n 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 me chanisms other than barotrauma after atelectatic storage may be respon sible for postpreservation and postreperfusion lung injury.