Revisiting static ice storage in clinical lung transplantation: Direct and continuous temperature monitoring of donor lungs followed by mathematical modeling

Background: In clinical lung transplantation (LTx), direct and continuous measurement of donor lung temperature during transport under static ice storage has rarely been reported.Although usually assumed to remain at 4°C, recent studies suggest that temperatures may approach 0°C.This study aimed to establish direct and continuous monitoring of donor lung temperature, fit temperature changes to a mathematical model, and evaluate their association with clinical outcomes.Methods: This prospective single-center study included clinical LTx cases between July 2024 and January 2025.Direct temperature monitoring at the end of preservation (n=15) and continuous monitoring during preservation (n=10) were performed at both the lung surface and interlobar region using a sterile data logger.Temperature curves were fitted (n=8) with an exponential decay model validated in preclinical porcine experiments.Associations between end-of-preservation interlobar temperature (≤4°C vs. >4°C) and post-LTx outcomes were examined (n=15).Results: Median end-of-preservation temperatures were 8.6°C (range: 1.21-13.35°C)at the surface and 5.3°C (range: 0.15-12.10°C)at the interlobar region, but inter-case variability was observed.Nevertheless, temperature curves generally remained above freezing.Interlobar curves showed better model fitting than surface curves (median R-squared: 0.98 vs. 0.95).The J o u r n a l P r e -p r o o f >4°C interlobar group demonstrated significantly better primary graft dysfunction grades post-LTx (p=0.04), a trend not observed with surface temperature.Conclusions: Direct measurement showed that lungs preserved on ice generally remained above 0°C, but freezing injury could not be completely ruled out.Interlobar temperature more closely followed the mathematical model, reflecting graft temperature dynamics.An interlobar temperature >4°C was associated with better early graft function.