More is not better: The role of the leukocyte filter in ex vivo lung perfusion.

Abstract

A leukocyte filter has been empirically incorporated within ex vivo lung perfusion circuits since the advent of ex vivo lung perfusion. However, the utility of the leukocyte filter has never been fully defined, and studies have questioned the beneficial effects of the filter. Additionally, there have been suggestions that such filters may become quickly saturated in use requiring replacement for better effect. Thus, we sought to determine the effects of leukocyte filters on ex vivo lung perfusion and evaluated whether a conventional arterial filter would prove to be noninferior. Porcine donor lungs (n = 22) were extracted and placed on the Toronto ex vivo lung perfusion platform for 12 hours. Groups consisted of a leukocyte filter group (conventional ex vivo lung perfusion with a leukocyte filter), an arterial filter group (the conventional leukocyte filter was replaced with an arterial filter), a change of filter group where the leukocyte filter was clamped and exchanged for a fresh filter after 1 hour, and a no filter control group. Because of severely poor performance seen in the change of filter group, only lungs in the leukocyte filter, arterial filter, and no filter groups were then transplanted into porcine recipients and monitored during a 4-hour reperfusion period. The leukocyte filter, arterial filter, and no filter groups showed good lung function on ex vivo lung perfusion. The change of filter group demonstrated worse lung function on ex vivo lung perfusion. After transplant, the leukocyte filter, arterial filter, and no filter groups demonstrated equivalent early lung function performance, but on histological staining, the no filter group demonstrated increased lung injury over the other groups. Cytokine levels were not significantly different among groups. The traditional leukocyte filter should be used in the ex vivo lung perfusion circuit but can be exchanged for an arterial filter with noninferior performance. Changing the filter after 1 hour does not add therapeutic benefit and makes lung performance worse on ex vivo lung perfusion.