Ex Vivo Lung Perfusion With Perfusate Purification For Human Donor Lungs Following Prolonged Cold Storage

Background:Ex vivo lung perfusion has been developed as the most effective technique for assessing marginal donated lungs.This study attempts to establish an EVLP system and extend the operation time of EVLP to 12 hours by using perfusate purification technology instead of periodic perfusate replacement,which could reduce the cost of EVLP.Part OneMethods:Pigs were randomly divided into control group and warm ischemia group.In the warm ischemia group,we established the donation after cardiac death model by inducing ventricular fibrillation,and obtained the donor lungs after one hour of warm ischemia.Two groups of donor lungs were immediately connected to the self-built EVLP system after harvesting.EVLP was performed according to the standard procedure and stopped when oxygenation index,pulmonary compliance or pulmonary artery pressure reached the termination indications.The longest time for EVLP to maintain the physiological function of the two groups was observed,and the physiological parameters,blood gas analysis and electrolyte were recorded.Results:8 pigs were randomly divided into the control group and warm ischemia group,with 4 pigs in each group.There were no differences in donor body weight,cold perfusion time and total harvest time.EVLP was terminated in 4 cases mainly due to the decreas of oxygenation index and 4 cases mainly due to severe pulmonary edema.The average maintenance time of EVLP in control group was 6.50±1.80 hours,while that in warm ischemia group was 6.00±1.58 hours,p=0.691.During EVLP,pulmonary PO₂ decreased significantly in a short time before termination of EVLP in most cases;in the control group,pulmonary artery pressure increased significantly after 3 hours of EVLP in 2 cases;the changes of pulmonary compliance and peak airway pressure were more obvious in warm ischemia group.Both groups showed a gradual decrease in glucose and p H,but a gradual increase in concentration of sodium and potassium.Part TwoMethods:Human donor lungs rejected by the clinical lung transplantation team were obtained.After cold storage lasting 18-24 hours,lungs were randomly assigned to 2groups:a control group and a perfusate purification(PP)group.The control group underwent EVLP in the traditional way,while a dialyzer was added into the circuit as a bypass in the PP group with a displacement speed of 400ml/h.The effects on lung function,microenvironment,inflammatory response,and cell death were evaluated.Results:A total of 8 rejected donor lungs were obtained and each group was assigned to 4 cases of EVLP.Three cases were prematurely terminated because of serious lung edema and decreased lung function.There were no significant differences in airway pressure,pulmonary artery pressure,and oxygen concentration between the two groups in the first 8 hours.The PH in the control group was significantly lower than that in the PP group,and the levels of potassium and lactate were significantly higher than those in the PP group.Inflammatory markers increased in both groups,while IL-6 and IL-10 were higher in the PP group in the first 6 hours.Hematoxylin&eosin(HE)staining revealed lung injuries in both groups,but no significant difference was noted in the HE-stained slides.There were significantly more TUNEL-positive cells in the control group(69.5±2.3%)than in the PP group(47.5±2.2%)(P<0.001).Conclusions:Self-built EVLP system and self-made perfusate could be able to proceed successfully.Using the modified method of EVLP reduces the high cost caused by exchanging perfusion fluid per hour and could prolong the preservation time of donor lungs.