Continuous Hemodialysis during Ex Vivo Lung Perfusion Allows for Improved Maintenance of Perfusate Composition, without Compromising Functional Performance

Abstract

Purpose Extended periods of ex vivo lung perfusion (EVLP) lead to several inadvertent consequences including accumulation of lactate and increasing electrolyte concentrations in the perfusate. Cellular perfusate based systems, such as the OCS Lung and Vivoline LS1, require a membrane-exchange system for electrolyte correction if they are to maintain a desired perfusate hemoglobin concentration. We sought to determine whether continuous hemodialysis (CHD) of the perfusate would be a suitable modality for improving ionic homeostasis in extended EVLP without compromising functional outcomes. Methods Twelve porcine lungs were perfused using EVLP for 24 hours. Lungs in the treatment group (n=6) underwent continuous hemodialysis of the perfusate. Functional parameters, edema formation, inflammatory cytokines and histopathologic analysis were used to assess graft function. Electrolyte and lactate profiles were also followed to assess the efficiency of hemodialysis. Results Lungs in both treatment and control groups demonstrated stable and acceptable oxygenation for 24 hours. Lungs demonstrated stable compliance over the first 18 hours, followed by a slow decline over the last 6 hours of perfusion. There was no difference in oxygenation and compliance between groups. CHD-EVLP lungs had higher pulmonary vascular resistance and pulmonary artery pressures. Despite increased perfusion pressures, weight gain at both 12 and 24 hours was not different between groups. Perfusate sodium and lactate concentrations were significantly lower in the CHD-EVLP group. TNF-α, IL-6, and IL-8 perfusate concentrations were similar between groups. Histopathologic assessment of lung injury did not differ between groups. Conclusion The addition of continuous hemodialysis to EVLP allows for stable functional performance up to 24 hours and improved physiologic perfusate composition despite increased perfusion pressures.