LUNG TRANSPLANTATION

THE RIGHT COMBINATION

Modern hypothermic preservation has reduced freezing injury and improved post-transplant outcomes, but is temperature control alone enough to protect donor lungs during storage? Preclinical evidence suggests that modern preservation solutions must safeguard both temperature and inflation in equal measure.

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TAPPING INTO PRECLINICAL RESEARCH

THE MODERN ERA OF LUNG PRESERVATION

The modern era of donor lung preservation has seen numerous benefits in terms of post-transplant outcomes, owing to the elimination of freezing injury when utilizing controlled moderate hypothermia.

However, the physiological characteristics of donor lungs make them uniquely sensitive to pressure changes, in addition to freezing temperatures, due to their delicate alveolar structure and reliance on pressure gradients for gas exchange. For decades, the lung’s inflation pressure had not been actively controlled or monitored during traditional static storage. Preclinical research has demonstrated that airway pressure in donor lungs decreases over time due to ongoing aerobic metabolism, with the rate of oxygen consumption increasing at the upper end of the “moderate hypothermic” range.

Years of preclinical research have shown that pressure decreases over time due to ongoing aerobic metabolism. Literature has proven that this point holds true even under hypothermic conditions where metabolism is seen to slow down, but not completely stop.

It is essential to keep donor lungs cold and inflated during preservation.

Published data indicate that donor lungs do not maintain their initial inflation pressure during static hypothermic preservation. Preclinical literature shows that airway pressure decreases to about 60% of its starting pressure by about 7 hours, the average ischemic time in the Composite Allocation Score era. This suggests that donor lungs do not maintain their starting pressure as time elapses, likely resulting in underpressurized lungs upon arrival.^1,2

In addition, studies measuring gas concentration in stored lungs report decreasing oxygen concentration while carbon dioxide concentration increases due to potential metabolism by the terminal alveoli. These trends in oxygen consumption and carbon dioxide production increase with temperature, indicating that although hypothermic conditions slow down metabolic activity, it does not completely stop.³ It is important to note that as preservation temperature increases, this point becomes more exaggerated. This demonstrates the importance of controlling lung pressure when considering warmer preservation temperatures.

Taken together, these data argue that lungs maintain metabolic activity even during hypothermic preservation, likely resulting in declining airway pressures. Without active airway pressure control, there is a higher risk of delivering under-inflated grafts. When this idea is compounded with imprecise packing procedures, an initially under-inflated lung is at risk of dropping pressure even further during preservation due to the lungs’ aerobic state.

THE PARAGONIX BAROGUARD PRESERVATION SYSTEM

ENGINEERED TO EMPOWER.

When discussing optimal preservation conditions for donor lungs, it is essential that pressure control is included in the conversation. The literature demonstrates that donor lungs continue to undergo metabolic activity during preservation, even under hypothermic conditions.

To support these ongoing metabolic demands, BAROguard is designed to maintain airway pressure by drawing in fresh room air as needed to help preserve inflation throughout transport. By adding a mechanically controlled feature, BAROguard is able to achieve consistent and controlled airway pressures as well as maintain higher levels of oxygen than in a statically stored lung.

As the field of preservation continues to advance, future research should focus on how best to sustain the continued metabolic needs of donor lungs during hypothermic storage, especially if considering warmer preservation temperatures.

PURPOSE-BUILT TO CONTROL THERMAL DYNAMICS

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View References List

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Copeland et al. Donor heart and lung procurement: A consensus statement. JHLT 2020.\
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Krishnan et al., Procurement of lungs from brain-dead donors. Indian J Thorac Cardiovasc Surg 2021.
Langer, AATS MCS Industry Symposium 2025, Data on file. Delivering Textbook Outcomes in Lung Transplantation. September 5, 2025.
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