Assessment of Donor Lung Aspiration on the Ex Vivo Lung Perfusion (EVLP) Platform

Abstract

Donor aspiration of gastric contents represents a significant risk for lung injury and severe primary graft dysfunction after lung transplantation. Concern about possible aspiration is a common reason for clinicians to decline donor lungs for transplantation. The presence of bile acid in donor bronchial wash (BW) or bronchoalveolar lavage (BAL) fluid may indicate that a donor has aspirated. Previous reports have also shown that aspiration of bile acids cause increased inflammation in the lung. Ex vivo lung perfusion (EVLP) has become an important platform to assess questionable or "marginal" donors. In this study, we examined the relationship between possible donor aspiration and physiologic and biologic assessment of inflammation on EVLP. Large airway BW samples were collected from 270 donors (n=111 non-EVLP, n=159 EVLP) prior to transplantation. Bile acid levels were measured in BW samples using a commercially available colorimetric assay and clinically approved platform. Protein and biochemical measurements were made in perfusate samples collected hourly after the start of EVLP. The majority of donor lungs with clinically suspected aspiration were successfully transplanted after EVLP assessment (58% [23/40]). Donor bile acid levels were significantly higher in donor lungs that were ultimately declined for transplantation at the end of EVLP (0.28 vs. 0.12 μM, p<0.05, n=143). During EVLP there was a positive correlation between bile acid in the donor BW and inflammation (IL-8 levels (r=0.19, p<0.05, n=159)). Similarly, there was an increase in biochemical markers of cell death ([Ca2+]) in the EVLP perfusate of donors with high bile acid levels in BW (r=0.27, p<0.001, n=142). Following EVLP and transplantation, we observed no significant effects of donor bile acid levels on recipient ICU length-of-stay (r=0.09, p=0.35, n=117). Suspected donor aspiration can be assessed using the EVLP platform. Bile acid levels measured in the donor lung are associated with increased inflammation and lung injury observed during EVLP, but not recipient outcomes post-EVLP. Therefore, EVLP may be an ideal platform to identify marginal donor lungs suspected of aspiration but are ultimately suitable for clinical transplantation.