Phosphate buffered raffinose a simple solution for lung graft preservation.
NC Wright, DN Hopkinson, TE Shaw & TL Hooper.
Department of Cardiothoracic Surgery, Wythenshawe Hospital, Manchester, UK.
Background: Previously we have investigated which components of University of Wisconsin solution (UW) confer its superior properties as a preservation solution. A simplified solution of phosphate buffered raffinose (PBR) has been developed which in preliminary studies in the rat was as efficacious as UW. The purpose of this study was to compare PBR against UW using a new porcine ex-vivo model of lung reperfusion.
Methods: Porcine lung blocs were stored for 24 hours at 4(C following single pulmonary artery flush with either PBR (n=5) or UW (n=5) solutions. Left lung grafts were ventilated with room air and reperfused by a venovenous extracorporeal circulation from a support animal. Perfusion continued for four hours. Function was assessed by measuring graft effluent oxygen tension, graft blood flow and pulmonary artery pressure (reflecting pulmonary vascular resistance), and peak airway pressure (with a fixed tidal volume, reflecting compliance).
Results: Support animals remained stable for the period of reperfusion. Grafts functioned well in both groups, comparable to normal values. Functional results are presented with 95% CIs. Analysis was by repeated measures ANOVA with significance at p<0.05. At 4hr: PaO2(mmHg) = 85.2(16.2) UW vs 75.0(16.2) PBR, p=ns; flow(ml/min) = 466(65) UW vs 468(65) PBR p=ns; airway pressure (mmHg) = 21.0(3.1) UW vs 22.3(3.2) PBR, p=ns; and PA pressure (mmHg) = 22.3(3.0) UW vs 24.5(3.0) PBR, p=ns. Graft oedema expressed as percentage tissue water (SD) was 89.9(1.8)% UW vs 89.3(1.0)% PBR, p=ns (two-tailed simple t-test).
Conclusion: PBR is a far simpler and less expensive alternative to UW, and appears to provide the same level of lung graft protection.
