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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. 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). 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, P < 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, P < 0.001, Figure B). Lung thermography < 26°C at 8 min was significantly associated with a lower PaO 2 /FiO 2 , higher peak inspiratory pressure, higher lung weight gain, higher shunt ratio at 1 h and higher pulmonary vascular resistance at 8 min (P < 0.05, each). 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. [ABSTRACT FROM AUTHOR]

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. 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. 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, P < 0.05) and after 50 min (P < 0.01) as shown in Figure B. Lung weight gain at 50 min was significantly correlated with PaO 2 /FiO 2 , peak inspiratory pressure, shunt ratio, W/D, lung weight gain on the back table at 2 h (P < 0.01, each). In non-suitable cases, lung weight gain in evaluation phase was significantly higher than in recondition phase (P < 0.01). These results indicate that real-time lung weight measurement was feasible and can be a good early predictor of pulmonary function in cellular EVLP. [ABSTRACT FROM AUTHOR]