Cellular Ex Vivo Lung Perfusion Research Articles

Real-time Lung Weight Measurement During Cellular Ex Vivo Lung Perfusion: An Early Predictor of Transplant Suitability.

Increased extravascular lung water during ex vivo lung perfusion (EVLP) is associated with ischemia reperfusion injury and poor pulmonary function. A non-invasive technique for evaluating extravascular lung water during EVLP is desired to assess the transplant suitability of lungs. We investigated real-time lung weight measurements as a reliable method for assessing pulmonary functions in cellular EVLP using a porcine lung model. Fifteen pigs were randomly divided into 3 groups: control (no warm ischemia) or donation after circulatory death groups with 60 or 90 min of warm ischemia (n = 5, each). Real-time lung weight gain was measured by load cells positioned at the bottom of the organ chamber. Real-time lung weight gain at 2 h was significantly correlated with lung weight gain as measured on a back table ( R = 0.979, P < 0.01). Lung weight gain in non-suitable cases (n = 6) was significantly higher than in suitable cases (n = 9) at 40 min (51.6 ± 46.0 versus -8.8 ± 25.7 g; P < 0.01, cutoff = +12 g, area under the curve = 0.907). Lung weight gain at 40 min was significantly correlated with PaO 2 /FiO 2 , peak inspiratory pressure, shunt ratio, wet/dry ratio, and transplant suitability at 2 h ( P < 0.05, each). In non-suitable cases, lung weight gain at 66% and 100% of cardiac output was significantly higher than at 33% ( P < 0.05). Real-time lung weight measurement could potentially be an early predictor of pulmonary function in cellular EVLP.

Prone ex vivo lung perfusion protects human lungs from reperfusion injury

We previously reported beneficial effects of prone positioning during ex vivo lung perfusion (EVLP) using porcine lungs. In this study, we sought to determine if prone positioning during EVLP was beneficial in human donor lungs rejected for clinical use. Human double lung blocs were randomized to prone EVLP (n=5) or supine EVLP (n=5). Following 16 h of cold storage at 4°C and 2h of cellular EVLP in either the prone or supine position. Lung function, compliance, and weight were evaluated and transplant suitability determined after 2h of EVLP. Human lungs treated with prone EVLP had significantly higher partial pressure of oxygen/fraction of inspired oxygen (P/F) ratio [348 (291-402) vs. 199 (191-257) mm Hg, p=0.022] and significantly lower lung weight [926(864-1078) vs. 1277(1029-1483) g, p=0.037] after EVLP. 3/5 cases in the prone group were judged suitable for transplant after EVLP, while 0/5 cases in the supine group were suitable. When function of upper vs. lower lobes was evaluated, prone EVLP lungs showed similar P/F ratios and inflammatory cytokine levels in lower vs. upper lobes. In contrast, supine EVLP lungs showed significantly lower P/F ratios [68(59-150) vs. 467(407-515) mm Hg, p=0.012] and higher tissue tumor necrosis factor alpha levels [100.5 (46.9-108.3) vs. 39.9 (17.0-61.0) ng/ml, p=0.036] in lower vs. upper lobes. Prone lung positioning during EVLP may optimize the outcome of EVLP in human donor lungs, possibly by improving lower lobe function.

Real-Time Lung Weight Measurement to Assess Pulmonary Function During Cellular Ex Vivo Lung Perfusion

<h3>Purpose</h3> Increased extravascular lung water (EVLW) during ex vivo lung perfusion (EVLP) is associated with ischemia reperfusion injury and poor pulmonary function. A non-invasive technique for evaluating EVLW is desirable for assessing transplant suitability of lungs. The purpose of this study was to investigate real-time lung weight gain as a predictor of transplant suitability of lungs in cellular EVLP using a porcine lung model. <h3>Methods</h3> Fifteen pigs were randomly divided into three groups: control (no warm ischemia) or donation after circulatory death groups with 60 or 90 min of warm ischemia (n = 5, each). Lung weight gain was measured by loadcells positioned at the bottom of organ chamber during non-touch period when no one touched the organ chamber and the driving condition of EVLP was stable. Following the non-touch period, lung weight gain was assumed to continue at the same rate until the next non-touch period. The measurements were repeatedly performed, throughout the EVLP and estimated lung weight gain was calculated. Lungs were perfused according to the Lund protocol. At 2 h, transplant suitability was decided. <h3>Results</h3> Lung weight gains in suitable cases (n = 9) and non-suitable cases (n = 6) at 2 h were 34.9 ± 57.4 and 334.0 ± 142.7 g, respectively. Estimated lung weight gain was significantly correlated with lung weight gain on the back table (R = 0.979, P < 0.001, Figure A). Lung weight gain in non-suitable cases were significantly higher than in suitable cases at 40 min (48.3 ± 49.9 vs. -8.8 ± 25.7 g, <i>P</i> < 0.05) and after 50 min <i>(P</i> < 0.01) as shown in Figure B. Lung weight gain at 50 min was significantly correlated with PaO₂/FiO₂, peak inspiratory pressure, shunt ratio, W/D, lung weight gain on the back table at 2 h (<i>P</i> < 0.01, each). In non-suitable cases, lung weight gain in evaluation phase was significantly higher than in recondition phase (<i>P</i> < 0.01). <h3>Conclusion</h3> These results indicate that real-time lung weight measurement was feasible and can be a good early predictor of pulmonary function in cellular EVLP.

Lung Thermography as an Early Predictor of Pulmonary Function in Cellular Ex Vivo Lung Perfusion

<h3>Purpose</h3> Infrared thermography is a real-time and non-invasive technique for detecting low temperatures in poorly perfused areas. We hypothesized that the temperature of injured lungs may not increase as rapidly as that of non-injured lungs during the initial 1 h rewarming phase in ex vivo lung perfusion (EVLP). In this study, we investigated the effect of graft thermal changes during the rewarming phase on pulmonary function in cellular EVLP using a porcine lung model. <h3>Methods</h3> Fifteen pigs were divided into three groups: control group (no warm ischemia) or donation after circulatory death groups with 60 or 90 min of warm ischemia (n = 5, each). Thermal images of the lower lobes were continuously recorded from the bottom of organ chamber using infrared thermography. Lungs were perfused according to the Lund protocol. In the initial 1 h, lungs were gradually rewarmed by increasing the flow rate in a stepwise fashion. At 2 h, transplant suitability was decided, and lung tissue samples were collected to measure wet/dry (W/D). <h3>Results</h3> Lung surface temperatures of non-suitable cases (n = 6) were significantly lower than in suitable cases (n = 9) at 8 min (25.1 ± 0.6 vs. 27.8 ± 1.2°C, <i>P</i> < 0.001, cut-off = 26°C, AUC = 1.0, Figure A), while there was no difference between the two groups at 0-4 min and 12-120 min. There was a significant negative correlation between lung surface temperature at 8 min and W/D at 2 h in the lower lobes (R = -0.769, <i>P</i> < 0.001, Figure B). Lung thermography < 26°C at 8 min was significantly associated with a lower PaO₂/FiO₂, higher peak inspiratory pressure, higher lung weight gain, higher shunt ratio at 1 h and higher pulmonary vascular resistance at 8 min (<i>P</i> < 0.05, each). <h3>Conclusion</h3> These data suggest that a lung surface temperature of < 26°C at 8 min was significantly correlated with poor pulmonary function and transplant non-suitability. This finding indicates that lung surface temperature during the rewarming phase can be a good early predictor of pulmonary function in cellular EVLP and might be applicable for clinical EVLP.

Sequential Ex Vivo Lung Perfusion for Prolonged Lung Preservation: Does the Second EVLP Reset the Lung Conditions?

<h3>Purpose</h3> Ex vivo lung perfusion (EVLP) has the potential to expand the donor pool for lung transplantation by extending preservation times significantly beyond cold static preservation. We hypothesized that performing sequential EVLP would extend donor lung preservation time. <h3>Methods</h3> Ten lungs from Yorkshire pigs were procured in a standard fashion and randomized to 2 groups. Control lungs (n=5) underwent 16 hrs of cold ischemic time (CIT) and 2 hrs EVLP (EVLP). Sequential EVLP lungs (n = 5) underwent 4 hrs of CIT (CIT1), 2 hrs EVLP (EVLP1), 10 hrs of CIT (CIT2), then 2 hrs EVLP (EVLP2) (<b>Figure A</b>). Transplant suitability was assessed based on physiological parameters at 2 hrs in cellular EVLP. Lungs were evaluated using lung weight (LW), ultrasound, ATP levels, histology, and electron microscopy. <h3>Results</h3> EVLP2 had significantly higher PaO₂/FiO₂, lower shunt fraction, and A-a gradient compared to Control (p = 0.02, each, <b>Figure B</b>). LW ratio (LW 2 hrs / 0 hr) was significantly lower in EVLP2 vs. Control (p = 0.02, <b>Figure C</b>). Moreover, ultrasound score in whole lung and lower lobe to assess extravascular lung water was significantly lower in EVLP2 vs. Control (p = 0.04, p = 0.02, respectively, <b>Figure C</b>). ATP levels were significantly higher in EVLP2 vs. Control (p = 0.01). Histologic analysis of lungs in EVLP2 showed significantly reduced intra-alveolar edema, while there was no difference between groups in lung injury score. Electron microscopy demonstrated better preservation of endothelial cells and mitochondria in alveolar cells in EVLP2 lungs vs. Control. <h3>Conclusion</h3> Treating donor lungs with sequential EVLP resulted in superior oxygenation vs. lungs subjected to cold storage and 1 session of EVLP. Sequential EVLP was also associated with decreased LW ratio, lung edema, and higher ATP levels, in addition to favorable histology and electron microscopic findings. These suggest that sequential EVLP can have a potential role in prolonging lung preservation time.

Lung thermography during the initial reperfusion period to assess pulmonary function in cellular ex vivo lung perfusion.

Thermography is a noninvasive technology to detect low temperatures in poorly circulated areas. In ex vivo lung perfusion (EVLP), lungs are rewarmed to body temperature during the initial 1h. Currently, the effect of graft thermal changes during the rewarming phase on pulmonary function is unknown. In this study, we evaluated the correlation of lung surface temperature with physiological parameters, wet/dry ratio, and transplant suitability in Lund-type EVLP. Fifteen pigs were divided into three groups: control group (no warm ischemia) or donation after circulatory death groups with 60 or 90min of warm ischemia (n= 5, each). Thermal images of the lower lobes were continuously collected from the bottom of an organ chamber using infrared thermography throughout EVLP. At 8min, lung surface temperatures of nonsuitable cases were significantly lower than in suitable cases (25.1±0.6 vs. 27.8±1.2°C, p<0.001), while there was no difference in lung surface temperatures between the two groups at 0-4min and 12-120min. There was a significant negative correlation between lung surface temperatures at 8min and wet/dry ratio at 2h in the lower lobes (R =-0.769, p<0.001, cutoff=26°C, area under the curve=1.0). A lung surface temperature of <26°C was significantly correlated with poor pulmonary function and transplant nonsuitability. A lung surface temperature of ≥26°C at 8min is a good early predictor of transplant suitability in cellular EVLP and might be applicable in clinical EVLP.

Optical oxygen saturation imaging in cellular ex vivo lung perfusion to assess lobular pulmonary function.

Ex vivo lung perfusion (EVLP) is an emerging tool to evaluate marginal lungs in lung transplantation. However, there is no objective metric to monitor lobular regional oxygenation during EVLP. In this study, we developed oxygen saturation (SaO2) imaging to quantitatively assess the regional gas exchange potential of the lower lobes. Ten porcine lungs were randomly divided into control and donation after circulatory death (DCD) groups (n = 5, each). Lungs were perfused in cellular EVLP for 2 h, and multispectral images were continuously collected from the dorsal sides of the lower lobes. We examined whether lower lobe SaO2 correlated with PaO2/FiO2 (P/F) ratios in lower pulmonary veins (PV). The wet/dry ratio in lower lobes was measured and Monte Carlo simulations were performed to investigate the method's feasibility. There was a significant correlation between lower lobe SaO2 and the P/F ratio in lower PV (r = 0.855, P < 0.001). The DCD group was associated with lower SaO2 and higher wet/dry ratio than the control group (P < 0.001). The error of estimated SaO2 was limited according to Monte Carlo simulations. The developed technology provides a noninvasive and regional evaluative tool of quantitative lobular function in EVLP.

Significance of Lung Weight in Cellular Ex Vivo Lung Perfusion

BackgroundCurrently, pulmonary edema is evaluated via surgical inspection and palpation in donor lungs, and there is no quantitative standard diagnostic tool for evaluating pulmonary edema in donor procurement and ex vivo lung perfusion (EVLP). The purpose of this study was to investigate the significance of lung weight at the donor hospital and lung weight during EVLP as a complementary parameter of transplant suitability in EVLP. Materials and methodsTwenty-one of rejected human lungs were perfused in cellular EVLP. Transplant suitability was evaluated at 2 h as per standard criteria of Lund-protocol EVLP. ResultsLung weight at donor hospital was significantly correlated with PaO2/FiO2 (P/F) ratio in EVLP (r = −0.44). There was a significant difference in lung weight at donor hospital between suitable cases (n = 13) and nonsuitable cases (n = 8). Light lung group (lung weight at donor hospital < 1280 g; n = 17) was suitable for transplant in 76%, whereas none of heavy lung group (lung weight at donor hospital ≥ 1280 g; n = 4) was suitable (P < 0.05). Lung weight at 2 h and lung weight change during EVLP were significantly associated with P/F ratio at 2 h and transplant suitability (P < 0.05, each). ConclusionsOur findings demonstrate that lung weight at donor hospital, lung weight change, and lung weight at 2 h of EVLP might be a predictor of P/F ratio and transplant suitability in cellular EVLP.

Hyperinflation With Pulmonary Dysfunction in Donor Lungs With Smoking History During Lung Perfusion

BackgroundDonor lungs with smoking history are perfused in ex vivo lung perfusion (EVLP) to expand donor lung pool. However, the impact of hyperinflation of perfused lungs in EVLP remains unknown. The aim of this study was to investigate the significance of hyperinflation, using an ex vivo measurement delta VT, during EVLP in smoker's lungs. Materials and methodsSeventeen rejected donor lungs with smoking history of median 10 pack-years were perfused for 2 h in cellular EVLP. Hyperinflation was evaluated by measuring delta VT = inspiratory − expiratory tidal volume (VT) difference at 1 h. All lungs were divided into two groups; negative delta VT (n = 11, no air-trapping pattern) and positive delta VT (n = 6, air-trapping pattern). Transplant suitability was judged at 2 h. By using lung tissue, linear intercept analysis was performed to evaluate the degree of hyperinflation. ResultsThe positive delta VT group had significantly lower transplant suitability than the negative delta VT group (16 versus 81%, P = 0.035). The positive delta VT group was significantly associated with lower partial pressure of oxygen/fraction of inspired oxygen ratio ratio (278 versus 356 mm Hg, P = 0.049), higher static compliance (119 versus 98 mL/cm H2O, P = 0.050), higher lung weight ratio (1.10 versus 0.96, P = 0.014), and higher linear intercept ratio (1.52 versus 0.93, P = 0.005) than the negative delta VT group. ConclusionsPositive delta VT appears as an ex vivo marker of ventilator-associated lung hyperinflation of smoker's lungs during EVLP.

Human Lungs Airway Epithelium Upregulate MicroRNA-17 and MicroRNA-548b in Response to Cold Ischemia and Ex Vivo Reperfusion.

Lung ischemia-reperfusion injury after transplantation is associated with worse clinical outcomes. MicroRNA (miR) are critical regulators of gene expression that could provide potential targets for novel gene therapy. Herein, we aim to examine the feasibility of using the ex vivo lung perfusion (EVLP) platform to examine the changes in miR expression in human lungs in response to cold ischemia and ex vivo reperfusion (CI/EVR). Twenty-four human lungs were perfused in cellular EVLP system for 2 h, and tissue samples were obtained before and after EVLP as well as from control donors. MicroRNA expression profiling of the lung tissue was performed using next-generation sequencing and downstream predicted target genes were examined. In situ hybridization assay of the validated miR was used to identify the expressing cell type. After 2 h of EVLP, cytokines production was significantly increased (IL-1β, IL-6, IL-8, IL-10, and TNF-α). MicroRNA sequencing identified a significant change in the expression of a total of 21 miR after CI and 47 miR after EVR. Validation using quantitative polymerase chain reaction showed significant upregulation of miR-17 and miR548b after CI/EVR. Downstream analysis identified abundant inflammatory and immunologic targets for miR-17 and miR-548b that are known mediators of lung injury. In situ hybridization assays detected positive signals of the 2 miR expression in alveolar epithelial cells. This study demonstrates the feasibility of using the EVLP platform to study miR signature in human lungs in response to CI/EVR. We found that miR-17 and miR-548b were upregulated in alveolar epithelial cells after CI/EVR, which merit further exploration.

Alveolar Epithelial Cells Up-Regulate microRNA-17 & microRNA-548b in Response to Cold Ischemia - Ex Vivo Reperfusion of Human Lungs

Ischemia-reperfusion injury after lung transplantation (LTx) is associated with early graft dysfunction, increased morbidity, and mortality. MicroRNA (miR) are identified as critical regulators of gene expression which could provide potential targets for novel gene therapy. Herein, we aim to examine the feasibility of using the ex vivo lung perfusion (EVLP) platform to study miR expression change in human lungs in response to cold ischemia and ex-vivo reperfusion (CI/EVR). Prior to initiating the clinical EVLP program at our institution, our group has established a biobank of human lung tissue according to an approved (cellular) EVLP research protocol. Twenty-four donor lungs that did not meet the ideal criteria for LTx or did not match to an available recipient were used for this study. Samples were obtained after cold ischemia (median 6, interquartile range 5-13 hrs), and after 2 hrs of EVLP. Control samples were obtained from different 6 donors that were stored directly without cold ischemia or reperfusion. MicroRNA expression profiling of lung tissue was performed using next generation sequencing. MicroRNAs with the most significant fold change were validated and detected in the tissues using In-situ hybridization assay. Assessment of inflammatory response of the EVLP model using cytokines array showed significant up-regulation of IL-1β, IL-6, IL-8, IL-10, and TNF-α in the perfusate after 2 hours EVLP. MicroRNA sequencing identified significant expression change of a total of 21 miR after cold ischemia and 47 miR after ex-vivo reperfusion when compared to control group. Validation using quantitative PCR showed significant up-regulation of miR-17 & miR548b after CI/EVR. Downstream analysis identified abundant inflammatory and immunologic targets for miR-17 and miR-548b that are known mediators of lung injury. Expression of miR-17 in the lung tissue had a significant negative correlation with IL-8 levels in the perfusate (R = -0.8, p=0.001). In-situ hybridization assays detected positive expression of miR-17 & miR548b in alveolar epithelial cells after CI/EVR. R. In this study, we were able to utilize EVLP model to study miR signature in human lungs after CI/EVR. The finding that alveolar epithelial cells up-regulate miR-17 & miR548b in response to CI/EVT is novel and warrant further investigation.

Selective Recruitment of Large Lower Lobe Atelectasis on Donor Back Table in Rejected Donor Lungs

Background.Large atelectatic areas in donor lungs are frequently resistant to standard recruitment maneuvers, producing a tenaciously low PO2/FiO2 ratio. The aim of this study is to investigate the optimal protocol for the recruitment of large atelectatic areas in the context of ex vivo lung perfusion (EVLP).Methods.Seventeen rejected lungs with large lower lobe atelectasis (≥40%) were divided into 2 groups: manual resuscitation (n = 5) and selective recruitment (n = 12). Transplant suitability was then evaluated in cellular EVLP. In the manual resuscitation group, following bronchoscopy, if the conventional recruitment maneuver was not successful, a bagging technique was utilized to resolve atelectasis in EVLP. In the selective recruitment group, a pediatric endotracheal tube was introduced to the lower lobe bronchus on the back table of the donor hospital. Selective recruitment of the lower lobe was accomplished while keeping peak inspiratory pressure <30 cm H2O for 30 seconds.Results.The average atelectasis size and lung weight in 17 donor lungs was 75.4 ± 20.6% and 960 ± 221 g, respectively. There were no significant differences between the 2 groups in all donor variables, except cold ischemic time (P = 0.001, 5.2 ± 0.5 versus 6.4 ± 0.7 hours). The selective recruitment group was associated with better transplant suitability (P = 0.035, 75% versus 20%), better PO2/FiO2 ratio (P = 0.186, 324 ± 89 versus 258 ± 87 mm Hg), lower lung weight (P = 0.057, 997.9 ± 229.2 versus 1377.2 ± 452.9 g), and better pathological score (P < 0.05, 1.0 ± 1.3 versus 2.8 ± 0.8) than the manual resuscitation group.Conclusion.A selective recruitment procedure is a safe and effective method of eliminating large atelectasis before EVLP.

A novel concept for evaluation of pulmonary function utilizing PaO2/FiO2 difference at the distinctive FiO2 in cellular exvivo lung perfusion-an experimental study.

For more accurate lung evaluation in exvivo lung perfusion (EVLP), we have devised a new parameter, PaO2 /FiO2 ratio difference (PFD); PFD1-0.4 = P/F ratio at FiO2 1.0 - P/F ratio at FiO2 0.4. The aim of this study is to compare PFD and transplant suitability, and physiological parameters utilized in cellular EVLP. Thirty-nine human donor lungs were perfused. At 2h of EVLP, PFD1-0.4 was compared with transplant suitability and physiological parameters. In a second study, 10 pig lungs were perfused in same fashion. PFD1-0.4 was calculated by blood from upper and lower lobe pulmonary veins and compared with lobe wet/dry ratio and pathological findings. In human model, receiver operating characteristic curve analysis showed PFD1-0.4 had the highest area under curve, 0.90, sensitivity, 0.96, to detect nonsuitable lungs, and significant negative correlation with lung weight ratio (R2 =0.26, P<0.001). In pig model, PFD1-0.4 on lower and upper lobe pulmonary veins were significantly associated with corresponding lobe wet/dry ratios (R2 =0.51, P=0.019; R2 =0.37, P=0.060), respectively. PFD1-0.4 in EVLP demonstrated a significant correlation with lung weight ratio and allowed more precise assessment of individual lobes in detecting lung edema. Moreover, it might support decision-making in evaluation with current EVLP criteria.

Reperfusion Inflammatory State of Human Lungs during Cellular Ex-Vivo Perfusion

Purpose Normothermic cellular ex-vivo lung perfusion (EVLP) can provide a platform for studying ischemia-reperfusion injury (IRI), with the donor lungs being the only source of cytokine appearance in the perfusate. The inflammatory effects of cellular EVLP on lungs are inadequately explored. Herein, we aimed to examine the reperfusion inflammatory state during cellular EVLP in relation to donor factors and impact on lung function. Methods For research purposes, 42 clinically rejected donor lungs underwent normothermic cellular EVLP with open left atrium and flow equivalent to 100% of cardiac output for 2 hours. Reasons for rejection were donor old age, smoking history, low PO2/FiO2 (P/F) ratio, or unavailability of a matched recipient. Perfusate samples were collected at the beginning of EVLP (0 hours), then at 1 and 2 hours of EVLP. Lung weight was measured at the end of EVLP as an indicator for the degree of edema. Data were presented as median (interquartile range). Results Interleukin (IL)-6, IL-8, IL-10, IL-1β, and tumor necrosis factor (TNF)-α were significantly up-regulated in the EVLP perfusate at 1 and 2 hours compared to baseline 0 hours (p Conclusion Cytokine array has shown that cellular EVLP is associated with reperfusion inflammatory state in human lungs. IL-1β and IL-10 were mostly affected by donor factors, while IL-6, IL-8, and TNF-α had the most effect on lung function during EVLP. These results suggest that cellular EVLP can be utilized to study human lung IRI and develop therapeutic targets.

The Protective Effect of Prone Positioning on Human Rejected Donor Lungs during Cellular Ex Vivo Lung Perfusion

Purpose We previously reported that prone positioning (PP) of porcine lungs during cellular ex vivo lung perfusion (EVLP) diminished inflammatory injury and improved oxygenation and other pulmonary parameters during cellular EVLP. We hypothesized that prone positioning of human lungs during cellular EVLP may diminish injury and improve function, as well. The aim of this study is to validate the previous results with porcine lungs and evaluate the potential benefits of PP EVLP with human rejected donor lungs. Methods Eleven human rejected donor lungs were flushed and stored for 15-16 hours with Perfadex. Lungs were then subjected to 2 hours of cellular EVLP with either maintenance of prone positioning (prone group, n = 6) or supine positioning (control group, n = 5). Lung function was evaluated using blood gas analysis, airway and vascular parameters, visual findings, wet/dry (W/D) ratio and lung weight at 2 hours of EVLP. Results Lung weight (LW) ratio (LW at 2 hours of EVLP/ LW prior to EVLP) was lower in Prone group than in Control group [median (interquartile range)] [1.09 (0.82-1.32) vs. 1.22 (1.01-1.50), p = 0.5] (not statistical significant). The PaO2/FiO2 (P/F) ratio of left atrial blood was significantly higher in Prone group than in Control [335.5 (297.2-392.5) vs. 198.0 (190.5-271.0) mmHg, p Conclusion These results demonstrate that PP during 2 hours of cellular EVLP result in less lung weight gain, and better P/F ratio, especially in the lower lobes. These results were consistent with our previous animal study, and suggest that prone positioning EVLP of rejected human donor lungs also may diminish IRI during EVLP.

Donor Lung Weight at Lung Procurement; Predictive Value for Transplant Suitability during Ex Vivo Lung Perfusion

Purpose Currently, pulmonary edema in donor lungs is evaluated via surgical inspection and palpation at procurement with no quantitative, standard diagnostic tool in use. The purpose of this study was to investigate the significance of lung weight at the donor hospital (LW0) as an indicator of pulmonary edema and predictor of transplant suitability in ex vivo lung perfusion (EVLP). Methods LW0 was recorded in standard donors (n = 53) and rejected donors (n = 69). Twenty-one rejected lungs were perfused in cellular EVLP and transplant suitability evaluated at 2 hours. Results There was a significant difference in LW0 between standard and rejected donors (814.7 ± 185.9 vs. 956.1 ± 275.1 g, p Conclusion Our findings demonstrate that donor lung weight could be a predictor of P/F ratio and transplant suitability during EVLP. The prospect for recovery of EVLP treated rejected donor lungs improved significantly if they weighed less than 1280 g.

Better Oxygenation in Upper Lobes Than in Whole Lungs in Marginal Human Donor Lungs Utilized for Cellular Ex Vivo Lung Perfusion

Purpose Anatomical regions of marginal donor lungs display significant heterogeneity in function raising the possibility that good functioning regions might be suitable for transplantation. The aim of this study was to compare gas exchange of upper lobes, which are possibly less susceptible to injury, with whole lungs using ex vivo lung perfusion (EVLP). Methods Nine rejected donor lungs were perfused for 2 hours of cellular EVLP utilizing the Swedish protocol. Transplant suitability was evaluated based on blood gas analysis, hemodynamics, ventilator parameters, palpation, visual findings, and lung weight. In order to assess upper lobe gas exchange, blood samples from upper lobe pulmonary vein (ULPV) were taken selectively at 2 hours of EVLP. PaO2/FiO2 (P/F) ratio, shunt fraction (SF), and A-a gradient in ULPV samples were compared with those of left atrium (LA). Results Upper lobes demonstrated a significantly higher P/F ratio [median (minimum - maximum)] [396 (315-583) vs. 284 (104-415), mmHg, p = 0.02, Figure A] and lower SF [21.8 (7.3-34.6) vs. 29.1 (22.7-73.9), %, p = 0.04] than whole lungs. Based on evaluation at 2 hours of EVLP, 6 of 9 lungs were deemed to be non-suitable for transplantation. In non-suitable group, P/F ratio in ULPV was significantly higher than that in LA [439 (315-583) vs. 245 (104-415) mmHg, p = 0.02, Figure B], whereas SF and A-a gradient of ULPV were significantly lower than those of LA [SF, 18.5 (7.3-34.6) vs. 34.8 (22.7-73.9) %, p = 0.04; A-a gradient, 224.9 (83.5-347.9) vs. 418.4 (246.2-569.6) mmHg, p = 0.02]. In contrast, no difference was found between the ULPV and LA parameters in lungs deemed suitable for transplant. Conclusion These results demonstrate that in marginal donor lungs judged to be non-suitable for transplant at 2 hours of EVLP, the majority of lungs have well-functioning upper lobes. These findings suggest that, in this setting, upper lobes may be suitable for lobar transplantation which could help reduce wait-list mortality.

Extravascular Lung Water Quantification in Donor Lungs

Purpose Extravascular lung water (EVLW) could change in donor lungs in a time-dependent fashion during procurement or Ex-Vivo Lung Perfusion (EVLP) and may vary across different zones. Current techniques for EVLW assessment are either subjective or not feasible in the clinical setting. An accurate and non-invasive diagnostic tool for monitoring EVLW would be desirable for donor lung assessment and management. Therefore, we studied the accuracy and reliability of direCt Lung Ultrasound Evaluation (CLUE) technique for the quantification of EVLW. Methods Eleven clinically rejected donor lungs underwent cellular EVLP for 2 hours. In CLUE, ultrasound images were taken directly from the lung surface. A scoring system was created for each point based on the percentage of B-lines. Images were graded according to the degree of edema. The following equation was used to calculate total lung and lobe scores using the number of images of each grade. CLUE total Score = (No. of Grade 1 images x 1 + No. of Grade 2 images x 2 + No. of Grade 3 images x 3 + No. of Grade 4 images x 4 + No. of Consolidation images x 5) / Total No. of images taken The images were reviewed by four blinded raters. CLUE scores and lung weight were measured before and after EVLP. Wet/dry (W/D) ratio was measured from tissue samples taken after EVLP. Results CLUE point score correlated with W/D ratio measured from tissue samples taken from the same location (n = 99, r = 0.86, p (P/F) ratio measured at a sample taken from the corresponding pulmonary vein (n = 20, r = -0.78, p Conclusion CLUE technique showed a substantial inter-rater reliability. CLUE scores were significantly correlated with lung weight, W/D, and P/F ratio. These findings demonstrate the reliability and accuracy of CLUE in quantifying EVLW, which can be applied to donor lung clinical assessment and management.

The protective effect of prone lung position on ischemia–reperfusion injury and lung function in an ex vivo porcine lung model

ObjectiveProne positioning has been shown to improve oxygenation in patients with lung injury. We hypothesized that prone positioning of lungs during ex vivo lung perfusion (EVLP) can not only improve oxygenation but also diminish ischemia–reperfusion injury (IRI). The aim of our study was to evaluate the potential benefits of prone positioning of lungs during EVLP compared with the standard supine position. MethodsTen pigs were kept in the supine position at room temperature for 2 hours after circulatory death after which lungs were procured and subjected to 5 hours of cold storage. Lungs then underwent 2 hours of cellular EVLP with either supine positioning (Control group, n = 5) or prone positioning (Prone group, n = 5). Lung function was evaluated by assessment of physiological parameters and tissue histology and cytokines. ResultsIRI in the Prone group was significantly less than in the Control group. Lungs in the Prone group were significantly associated with greater partial pressure of oxygen/fraction of inspired oxygen ratio median (minimum-maximum) (301 mm Hg [272-414 mm Hg] vs 166 mm Hg [109-295] mm Hg, P = .03), better static compliance (38.9 mL/cmH2O [31.1-44.3 mL/cmH2O] vs 21.5 mL/cmH2O [12.2-33.3 mL/cmH2O], P = .03), lower lung weight ratio (1.26 [1.24-1.41] vs 1.48 [1.36-2.34], P = .02), and lower interleukin-1β levels (1.6 ng/mL [0.9-5.3 ng/mL] vs 7.5 ng/mL [5.0-16.1 ng/mL], P = .04) compared with lungs in the Control group. ConclusionsThese data suggest that prone positioning of lungs during EVLP may diminish IRI during EVLP and improve lung function.

An experimental study of the recovery of injured porcine lungs with prolonged normothermic cellular exvivo lung perfusion following donation after circulatory death.

Donation after circulatory death (DCD) is an underused source of donor lungs. Normothermic cellular exvivo lung perfusion (EVLP) is effective in preserving standard donor lungs but may also be useful in the preservation and assessment of DCD lungs. Using a model of DCD and prolonged EVLP, the effects of donor warm ischemia and postmortem ventilation on graft recovery were evaluated. Adult male swine underwent general anesthesia and heparinization. In the control group (n=4), cardioplegic arrest was induced and the lungs were procured immediately. In the four treatment groups, a period of agonal hypoxia was followed by either 1h of warm ischemia with (n=4) or without (n=4) ventilation or 2h of warm ischemia with (n=4) or without (n=4) ventilation. All lungs were studied on an EVLP platform for 24h. Hemodynamic measures, compliance, and oxygenation on EVLP were worse in all DCD lungs compared with controls. Hemodynamics and compliance normalized in all lungs after 24h of EVLP, but DCD lungs demonstrated impaired oxygenation. Normothermic cellular EVLP is effective in preserving and monitoring of DCD lungs. Early donor postmortem ventilation and timely procurement lead to improved graft function.