Functional assessment of non-heart-beating donor lungs: prediction of post-transplant function

Objectives: To enable an increase in the numbers of donor lungs using organ s from non-heart-beating donors (NHBD). To develop an isolated ventilation and perfusion technique to assess the degree of warm ischaemic organ injury suffered prior to retrieval, thereby enabling identification of lungs with predictably good post-transplant function. Methods: Lungs from Landrace-Yo rkshire White cross pigs were retrieved after 1 (NPBD1), 2 (NPBD2) or 4 h ( NHBD4) post-hypoxic death induced by cessation of ventilation. Control orga ns were retrieved using standard techniques far each group from matched ani mals immediately following aortic cross-clamping (Control(1) and combined C ontrol(2,4)). Modified Euro-Collins pulmoplegia was used in all groups, pri or to ventilating a single lung with 100% oxygen and perfusion with neutrop hil-depleted and deoxygenated blood. For all of the lungs in the NHSD2 and combined Control(2,4) groups, and one of the successfully perfused NHBD4, t he contralateral lung was then transplanted with post-transplant function a ssessed for 12 h. All animals were anaesthetized throughout and euthanased without regaining consciousness. Results: On assessment, oxygenation after 5 min of perfusion did not differ between NHBD1 (n = 4) vs. Control(1) (n = 5; analysis of variance (ANOVA), P = 0.152). However, oxygenation had dete riorated significantly in the NHBD2 group (n = 6) vs. Control(2,4) (n = 8; ANOVA, P < 0.0005) and was significantly poorer than initial values after 8 min (unpaired t-test with Bonferroni correction, P < 0.03). In NHBD4 (n = 6), four lungs failed assessment due to the development of gross pulmonary oedema, although the remaining pair functioned as well as Control(2,4). Pos t-transplantation, NHBD2 (n = 6) contralateral lungs showed significantly p oorer overall oxygenation, (mean +/- SD, 46 +/- 22 kPa) when compared with Control(2,4) (n = 6; 59 +/- 16 kPa; ANOVA, P = 0.001), although oxygenation was satisfactory. The contralateral organ from one successfully perfused N HBD4 lung functioned well post-transplantation. Conclusions: The significan t deterioration in oxygenating performance seen during assessment after 2 h warm ischaemia and the idiosyncratic function after 4 h warm ischaemia ind icates the importance of functional testing of NHBD lungs. The similar dete rioration in oxygenating performance seen post-transplantation in the contr alateral lungs suggests that this method detects functional warm ischaemic lung injury. (C) 2001 Elsevier Science B.V. All rights reserved.