Real-Time Lung Weight Measurement: A Simple Predictor for Clinical Outcomes of Ex-Vivo Lung Perfusion

Abstract

Lung weight (LW) gain is a typical characteristic of ischemia reperfusion injury in ex-vivo lung perfusion (EVLP). However, LW gain data is available only at the end of EVLP. Additionally, objective physiological parameters useful in EVLP evaluation are limited. The study purpose was to investigate the usefulness of real-time LW measurement to assess pulmonary edema and to predict clinical outcomes. LW at back table was measured before and after EVLP. During acellular EVLP, real-time LW was continuously measured by a scale attached under the organ chamber. The LW change (weight change per time, g/min) was measured during the non-touching period at multiple time points and the estimated LW gain was calculated by LW change and its duration. Transplant suitability was judged based on the standard criteria including trend of physiological parameters and palpation findings. Ten lungs were perfused at our institute and 8 lungs were clinically transplanted. All patients survived and primary graft dysfunction (PGD) grade at 72 hours were Grade 0-1, n = 6; Grade 2, n = 2; Grade 3, n = 0. Estimated LW gain during the entire perfusion period significantly correlated with LW gain at the back table (n = 10, r = 0.95, p < 0.01, Fig. 1A). Furthermore, initial LW gain (0-60 min) had a significant correlation with back table LW gain, compared with LW gain after 60 min of EVLP (n = 10, r = 0.79, p < 0.01, Fig. 1B). Non-suitable group had significantly higher initial LW gain compared to suitable group (120 ± 30 vs -17 ± 56 g, p = 0.02, Fig. 1C). Unfavorable outcome group (defined as non-suitable or PGD grade 2-3) group had significantly higher initial LW gain compared to favorable outcome group (defined as PGD grade 0-1, 75 ± 56 vs -32 ± 58 g, p = 0.02, Fig. 1D). The data suggest that LW gain calculated by real-time LW measurement might be useful to assess pulmonary edema during EVLP. Initial LW gain at 0-60 min of EVLP might be a predictor of transplant suitability and clinical outcomes.