Objective : If lungs could be retrieved for transplant after circulatory arrest, the shortage
of donors might be significantly alleviated. Great controversy still exists concerning both the
optimal method and gas mixture for alveolar expansion of pulmonary grafts in these nonheartbeating
donors.
Methods : We compared the effect of different postmortem conditions on graft function
in an isolated, pressure-limited reperfusion and room air ventilated lung model. Rabbits
(n=4 in each group) were sacrificed and left at room temperature with lungs either deflated
(Defl), inflated with room air (Infl-RA) or ventilated with room air (Vent-RA) or 100%
nitrogen (Vent-N2). Four hours postmortem, lungs were reperfused with homologous,
diluted and desoxygenated blood up to 4 hours. Peak airway pressure (AwP), mean
pulmonary artery pressure (PAP) and flow (PAF), total pulmonary vascular resistance (TPVR),
lung weight gain (DW), arteriovenous oxygen (Dv-aPO2) and carbon dioxide (Da-vPCO2)
pressure gradients were recorded. Wet-to-dry weight ratio (W/D) at end of reperfusion and
lung survival (LS), defined as PAF> 5ml/min, were calculated.
Results : Mean values ± standard error of the mean at 1 hour of reperfusion (= max PAF)
are listed.
+ p < 0.05 all groups versus control value (no ischemia)a; * p < 0.05 Infl-RA, Vent-RA, and
Vent-N2 versus Defl; ^ not significant Vent-N2 versus Vent-RA (by analysis of variance);
W.U.: Wood Units (mmHg/L/min)
Conclusions :
1) TPVR was significantly higher in ischemic lungs, especially when Infl-RA, resulting in
lower PAF;
2) Postmortem Infl-RA is as good as Vent-RA in counteracting edema formation and in
preserving gas exchange following reperfusion when compared to Defl;
3) Vent-N2 was equal to Vent-RA.
4) Therefore, prevention of alveolar collapse itself but not continued supply of oxygen
during warm ischemia will confer a functional advantage on reperfusion.
(This work is supported by a grant from NFWO-levenslijn n° 7.0036.94)