A simplified preservation method for lungs donated after cardiac death

Porcine lungs perfused with three different flows using the 8-h open-atrium cellular ex vivo lung perfusion technique

The number of lung transplantations is limited due to the shortage of donor lungs fulfilling the standard criteria. The ex vivo lung perfusion (EVLP) technique provides the ability of re-evaluating and potentially improving and treating marginal donor lungs. Accordingly, the technique has emerged as an essential tool to increase the much-needed donor lung pool. One of the major EVLP protocols, the Lund protocol, characterized by high pulmonary artery flow (100% of cardiac output [CO]), an open atrium, and a cellular perfusate, has demonstrated encouraging short-EVLP duration results. However, the potential of the longer EVLP duration of the protocol is yet to be investigated, a duration which is considered necessary to rescue more marginal donor lungs in future. This study aimed to achieve stable 8-h EVLP using an open-atrium cellular model with three different pulmonary artery flows in addition to determining the most optimal flow in terms of best lung performance, including lung electrolytes and least lung edema formation, perfusate and tissue inflammation, and histopathological changes, using the porcine model. EVLP was performed using a flow of either 40% (n = 6), 80% (n = 6), or 100% (n = 6) of CO. No flow rate demonstrated stable 8-h EVLP. Stable 2-h EVLP was observed in all three groups. Insignificant deterioration was observed in dynamic compliance, peak airway pressure, and oxygenation between the groups. Pulmonary vascular resistance increased significantly in the 40% group (p < .05). Electrolytes demonstrated an insignificant worsening trend with longer EVLP. Interleukin-8 (IL-8) in perfusate and tissue, wet-to-dry weight ratio, and histopathological changes after EVLP were insignificantly time dependent between the groups. This study demonstrated that stable 8-h EVLP was not feasible in an open-atrium cellular model regardless of the flow of 40%, 80%, or 100% of CO. No flow was superior in terms of lung performance, lung electrolytes changes, least lung edema formation, minimal IL-8 expression in perfusate and tissue, and histopathological changes.

Effects of immediate versus delayed ex-vivo lung perfusion in a porcine cardiac arrest donation model

OBJECTIVE

Ex-vivo lung perfusion is a promising tool to evaluate and recondition marginal donor lungs usually after a cold static preservation. The concept of continuous organ perfusion is supposed to reduce ischemic damage; however, the optimal perfusion protocol has not been established yet. The aim of this study was to compare immediate ex-vivo lung perfusion (I-EVLP) to delayed ex-vivo lung perfusion (D-EVLP) after a certain cold static preservation period on lung function in a large animal model.

METHODS

In a porcine model, lungs were procured after circulatory death and 60 min of no-touch warm ischemia. Lungs were preserved with single-flush cold low potassium dextran solution and prepared either for I-EVLP (n = 8) or stored cold for 9 h with subsequent D-EVLP (n = 8). Functional outcomes and morphology were compared during 4 h of ex-vivo lung perfusion, using STEEN Solution^TM as perfusion solution.

RESULTS

Pulmonary functional data, perfusate activities of lactate dehydrogenase, alkaline phosphatase, and products of lipid peroxidation did not differ significantly. There was a trend toward lower wet-dry ratio (I-EVLP: 13.4 ± 2.9; D-EVLP: 9.1 ± 2.5) and higher ΔpO₂ in D-EVLP group (I-EVLP: 209 ± 51.6 mmHg; D-EVLP: 236.3 ± 47.3 mmHg).

CONCLUSION

In this donation-after-circulatory-death model, 9 h of cold static preservation followed by ex-vivo lung perfusion results in comparable pulmonary function to I-EVLP as indicated by oxygenation capacities and wet-dry ratio. Our findings indicate that prolonged cold static preservation prior to ex-vivo lung perfusion is as safe and effective as I-EVLP in the procurement of donor lungs.

Excellent long-term outcome with lungs obtained from uncontrolled donation after circulatory death

We aimed to propose a simple and effective preservation method in lungs procured for transplantation from uncontrolled donation after circulatory death (uDCD) associated with excellent long-term results. Outcome measures for lung recipients were survival and primary graft dysfunction (PGD) grade 3. Survival was estimated using the Kaplan-Meier method. A total of 9 lung uDCDs were evaluated and 8 lung transplants were performed. Mean no-flow time was 9.8 minutes (standard deviation [SD] 8.6). Mean time from cardiac arrest to topical cooling was 96.8 minutes (SD 16.8). Preservation time was 159 minutes (SD 31). Ex vivo lung perfusion was used to assess lung function prior to transplantation in 2 cases. Mean recipient age was 60.8 years (SD 3.1), and mean total ischemic time was 678 minutes (SD 132). PGD grade 3 was observed in 2 cases (25%). The 1-month, 1-year, and 5-year survival rates were 100%, 87.5%, and 87.5%, respectively. Mean follow-up was 52 months. The logistic complexity of procuring lungs from uDCDs for transplantation requires the development of new strategies designed to facilitate this type of donation. A program based on strict selection criteria, using a simple and effective preservation technique, may recover lung grafts with excellent long-term posttransplant outcomes.

Do we need to cool the lung graft after ex vivo lung perfusion? A preliminary study

BACKGROUND

After normothermic ex vivo lung perfusion (EVLP), pulmonary grafts are usually flush-cooled and stored on ice until implantation although evidence for this practice lacks. We compared outcomes between 2 post-EVLP preservation strategies in a porcine left single-lung transplantation model.

MATERIAL AND METHODS

After cold flush and 2-h EVLP, donor lungs were prepared and split. In [C], (n = 5) lungs cooled on device to 15°C were preserved in ice-water; in [W] (n = 5), lungs were disconnected from EVLP at 37°C and kept at room temperature. The left lung was transplanted in a recipient animal. Posttransplant, 6 h-monitoring included hourly assessment of pulmonary vascular resistance, pulmonary artery pressure, plateau airway pressure, compliance, and oxygenation before and after exclusion of the right lung. Lung biopsies and bronchoscopy with bronchoalveolar lavage (BAL) were performed at retrieval, at the end of EVLP (R lung), and 1 and 6 h after reperfusion (L lung).

RESULTS

Lungs in [W] showed the highest compliance (P < 0.05) and the lowest plateau airway pressure (not statistically significant) throughout the whole reperfusion period. Oxygenation and pulmonary artery pressure were similar between groups. Pulmonary vascular resistance was stable in [C], but rose after reperfusion in [W]. Histologic signs of lung injury and BAL neutrophilia were more pronounced in [C] at 1 h (not statistically significant and P < 0.05, respectively). BAL cytokine levels and lung tissue expression of intercellular adhesion molecule 1 did not differ between groups.

CONCLUSIONS

Normothermic preparation after EVLP results in similar graft performances compared with lung cooling after EVLP.