Air embolism during liver procurement: an underestimated phenomenon? A pilot experimental study.

Background: Intrahepatic air embolism can occur during liver transplantation, jeopardizing the posttransplant outcome. Until now, the role of the procurement in the origin of intrahepatic air remains unclear; it might be underestimated. In this pilot study using magnetic resonance imaging (MRI), we observed a substantial amount of air trapped in porcine livers during multiorgan procurement. We quantified the amount of air, examining whether it could be reduced by avoiding direct contact of air with the lumen of the hepatic vasculature during procurement and back-table preparation.

Methods: Five livers (control group) were procured according to standard techniques for comparison with 6 livers (modified group) where air could not enter into the livers due to clamping of the vasculature. MRI was performed during continuous machine perfusion (MP) preservation there after. We counted the number of black signal voids on T(2)*-weighted images, which were indicative of air bubbles within the hepatic contour. Additionally, an MRI contrast agent (gadolinium-diethylene triamine pentaacetic acid [Gd-DTPA]) was injected into the hepatic artery and circulated by MP. Insufficiently perfused areas with less contrast enhancement were analyzed quantitatively in T(1)-weighted images and expressed as the percentage of total liver volume.

Results: The images of the control livers showed more air bubbles compared with the modified group (45 ± 27 vs 6 ± 3; P = .004). The percentage of insufficiently perfused areas was higher among the control compared with the modified group (28.0 ± 15.8% vs 2.6 ± 4.6%; P = .047) on first-pass postcontrast T(1)-weighted images. After recirculating the contrast agent, insufficiently perfused areas showed similar localizations and contours within every liver.

Conclusion: These data suggested that a substantial amount of air enters into the hepatic microcirculation through direct contact of air with the hepatic vasculature during standard procurement and back-table preparation. Avoiding opening the hepatic vessels to air substantially reduced this phenomenon.