BIO1: Ice Is Not 4°C: Thermodynamic Characterization of Livers Preserved on Ice Vs Advanced Hypothermic Preservation Technology

Abstract

Background: Clinical literature and conventional knowledge assumes that the temperature of donor livers stored on ice is 4°C. However, this assumption is not backed by empirical data as the typical environment of organ storage in solution is not measured or controlled, increasing risk of freezing injury. In an era where programs are evaluating the clinical and logistical tradeoffs of various perfusion strategies, it is important to quantify the actual temperature of livers stored on ice. Methods: Porcine livers were packaged in a traditional manner within 3 bags (3M) and placed on ice in a cooler (n=3) or using an advanced hypothermic technology (LIVERguard) (n=3). 2L preservation solution was in the organ bag, 2L saline in the second bag. Temperature probes were inside the liver tissue, liver surface, and in the saline bag. Temperatures were captured every 30 seconds, for up to 15 hours. Results: A total of 10,800 temperature measurements were analyzed between the two groups. Average liver surface temperatures evolved from an initial 5.9°C to 0.8°C (1 hr) to -0.1°C (4 hrs) in the ice group and from an initial 7.3°C to 7.3°C (1 hr), to 6.9°C (4 hrs) in LIVERguard group. Saline temperatures were like the surface temperatures. The starting temperature for ice was (-)6°C and approached 0°C at 8 hours. Average liver tissue temperature evolved from 5.7°C to 1.2°C (4 hrs), 0.2°C (8 hrs) and 0.1°C (12 hrs) in the ice group and from an initial 7.5°C to 6.8°C (4 hrs), 6.2°C (8 hrs), and 5.8°C (12 hrs) in LIVERguard group. Conclusions: Donor livers packaged and preserved on ice undergo rapid drop in temperature, approaching freezing in an uncontrolled manner. Actual temperatures are lower than the historically assumed 4°C. In contrast, donor livers packaged using LIVERguard remained between 4°C and 8°C. Centers may benefit from adopting controlled hypothermic strategies to prevent cold injury to donor livers.