Effects of ventilation during warm ischaemia followed by ex-vivo lung perfusion in a sheep model.

INTRODUCTION

Uncontrolled Donation after Circulatory Death (uDCD) has been considered an alternative to expand the lung donor pool. A key variable in these procedures is whether ventilation is maintained during the ischaemic interval. The present study evaluated the impact of ventilation during warm ischaemia in ovine DCD lungs, followed by functional assessment through Ex Vivo Lung Perfusion (EVLP).

METHODS

Ovine lungs were procured from a local slaughterhouse and flushed in situ. Lungs were then assigned to two groups: Ventilated (V) or Non-Ventilated (NV) during 120-minutes of warm ischaemia (WI), followed by 120-minutes of cold storage. EVLP was conducted for 240-minutes using a low-flow strategy, pressure-controlled ventilation, and a custom-made perfusion solution. Lung biopsies and perfusate samples were collected. Histopathological evaluation was performed; ventilatory and perfusion parameters were monitored.

RESULTS

After 240-min of EVLP, both groups presented an increase in the compliance (Cdyn) (p = 0.0001), pO2 (p = 0.0047), pCO2 (p = 0.0155), and lactate (p = 0.0001), without differences between the groups. Histopathology analysis indicated that haemorrhage after WI was higher in NV (p < 0.001) than V. Inflammatory cytokines gene expression was increased in V vs. NV at the end-EVLP, but no differences were seen, 24h later.

DISCUSSION: Ventilation did not confer a clear advantage in the functional status of the lungs after EVLP and may even be associated with transient increases in inflammatory and apoptotic responses. These findings suggest that immediate inflation alone may be sufficient to preserve graft quality prior to transplantation, and that preservation strategies should not primarily focus on mechanical ventilation.