Lung recruitment after cardiac arrest during procurement of atelectatic donor lungs is a protective measure in lung transplantation

Abstract

Background: Brain-dead donors are susceptible to pulmonary atelectasis (AT). In procurement surgery, lung recruitment under circulatory conditions and cold-flushing for atelectatic donor lungs often provoke graft injury due to the acute blood inflow. We hypothesized that lung recruitment without blood circulation can mitigate graft injury. This study aimed to examine the benefits of lung recruitment subsequent to cardiac arrest using a porcine lung-transplant model.

Methods: Thirteen donor pigs were categorized into the non-atelectatic (No-AT) group (n=3) representing a healthy control group; AT-BCR group (n=5), in which AT was reverted by conventional blood-circulated recruitment (BCR); and AT-no-BCR group (n=5), in which AT was reverted by no-BCR following circulatory arrest. In the atelectatic donor models, the left main bronchus was ligated for 24 hours prior to lung procurement. Left lung transplantation (LTx) was subsequently performed in the thirteen recipient pigs. After 6 hours evaluation, the recipients were euthanized and the lung grafts were excised.

Results: The post-transplant PaO₂/FiO₂ ratio was significantly higher in the AT-no-BCR group than in the AT-BCR group (P=0.015). Wet/dry ratio, histological findings of graft injury and tissue interleukin-8 expression in the AT-no-BCR group were similar to those of the No-AT group.

Conclusions: Lung recruitment without circulation after circulatory arrest could be more protective for atelectatic donor lung than the conventional procedure.

Keywords: Lung transplantation (LTx); atelectasis; lung recruitment maneuver; protective procurement.

Figure 1

Three experimental groups were defined according to the presence or absence of AT intervention and the timing of lung recruitment maneuver. In the AT-no-BCR group, lung recruitment was performed following aortic clamping and circulatory arrest. AT, atelectasis; BCR, blood-circulated-recruitment.

Figure 2

Macroscopic findings of AT donor model and lung graft procured from AT donors. (A) In AT donor groups, left main bronchus was clamped with tourniquet. Left lung was promptly collapsed completely; (B) macroscopic findings of lung graft in AT-BCR group immediately after procurement; (C) macroscopic findings of lung graft in AT-no-BCR group immediately after procurement. AT, atelectasis; BCR, blood-circulated recruitment.

Figure 3

Comparison of post-transplant lung function among the three groups. (A) PaO₂/FiO₂ ratio; (B) mean PAP with occluding right main pulmonary artery; (C) dynamic compliance of the lung graft. AT, atelectasis; BCR, blood-circulated recruitment; PAP, pulmonary arterial pressure.

Figure 4

Comparison of post-transplant graft tissue injury. (A) W/D ratio and (B) tissue IL-8 levels of graft tissue excised after the 6 hours post-transplant time; W/D ratio, wet weight-to-dry weight ratio; AT, atelectasis; BCR, blood-circulated recruitment.

Figure 5

Representative histological findings in the graft tissue stained with hematoxylin and eosin at the end of the 6 hours evaluation after lung transplantation. AT, atelectasis; BCR, blood-circulated recruitment.

Figure 6

Lung injury score in the graft tissue at the end of the 6 hours evaluation after lung transplantation. Higher intra-alveolar edema, neutrophilic infiltration and hyaline membrane formation was observed in the AT-BCR group than in other groups. AT, atelectasis; BCR, blood-circulated recruitment.