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Transplant surgery in an OR

LUNG TRANSPLANTATION

PRESSURE POINTS

So much of organ procurement happens in the margins. Subtle shifts in temperature and pressure may go unseen, yet can meaningfully impact the viability of a donor organ. For donor lungs, which are uniquely sensitive to environmental factors, this lack of visibility carries even greater risk. So what changes when those variables finally become visible?
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separating evidence from assumption

ACHIEVING A CONSENSUS - OR CONVENIENCE?

Modern preservation standards have shifted away from traditional ice storage. However, there are persistent misconceptions that affect how organ preservation research is interpreted and applied in clinical practice.
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Even in the modern era, foundational research questions on preservation temperature are frequently oversimplified. A thorough understanding of the scope, assumptions, and limitations of the current body of evidence is critical to allow for educated decision making in clinical settings. In truth, there is no consensus on a single, specific, "optimal" temperature for lung preservation, as all studies cover a range of storage temperatures.   

THE SINGLE ACCEPTED CONSENSUS...ICE IS TOO COLD.

The 2024 AATS Expert Consensus Document on Current Standards in Donor Lung Procurement and Preservation states that studies investigating static cold storage between 4°C and 10°C support the use of these warmer temperatures for safe storage of donor lungs.1 Co RIIa, LoE B-NR, 100% consensus.

THE (IN)ACCURACIES OF REPORTING

Temperatures have not been consistently measured and reported in published lung preservation studies that claim a single, exact temperature. These inconsistencies in temperature reporting in peer-reviewed publications have led to ongoing confusion in the lung transplant field.
 
For example, donor lungs were historically preserved on ice for transport with the intention of maintaining their temperature at approximately 4°C. Recently published work has demonstrated that this practice in fact brings the temperature down to close to 0°C, rather than the often-cited 4°C.14
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Temperature Dynamics of Porcine and Human Lungs During Static Ice Storage: Ice Is Not 4 °C
Cenik, et al. 2025, Journal of Clinical Medicine.

In this study of traditional static ice storage, the actual tissue temperature of the lungs was <2°C and the temperature of the Perfadex was 0°C within 3 hours of ice storage, demonstrating that the underlying assumption of ice storage at 4°C is not feasible. 

AND YET...

Despite this evidence, recent studies of lung preservation continue to incorrectly refer to ice storage as 4°C.  
 
Additionally, these recent studies fail to measure and report any data on the organ environment, preservation solution, or actual organ tissue temperature. All that is reported is the temperature of which the storage device is set. This gap in data incorrectly assumes that the temperature of the storage environment is equivalent to the actual temperature of the organ.
 
Regardless, the intervention arm of the studies is labeled as “10°C,” a single temperature, despite no actual measured organ tissue or environment temperature. 

EXPOSING THE BLIND SPOT

 
The Hidden Flaw in Preservation Temperature Data Reporting15-19
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A PARAGONIX CLINICAL REGISTRY

GUARDIAN-LUNG

The GUARDIAN-Lung Registry is one of the first means to study and compare traditional ice storage against FDA-regulated static controlled moderate hypothermic lung preservation, including both the LUNGguard and BAROguard preservation systems.

Several reports of the GUARDIAN-Lung data have been presented, each including data collected from the embedded temperature probe that continuously measures the temperature of the preservation solution surrounding the lungs.2-7

To date, the only transparently reported evidence comes from the GUARDIAN-Lung Registry, which has demonstrated that lung preservation at a range of 4–8 °C is safe and effective.

PURPOSE-BUILT TO CONTROL THERMAL DYNAMICS

ACCURACY OF TEMPERATURE MEASUREMENTS

AMBIGUOUS CONCLUSIONS?

[Static lung storage at 10°C maintains mitochondrial health and preserves donor organ function]

“...preliminary studies published more than 30 years ago have suggested that 10°C is the optimal lung storage temperature.”

- ALI ET AL, 2021. Sci Transl Med.

DEFINING INPUT VS OUTPUT

IN TEMPERATURE-BASED PRESERVATION STUDIES 

 
Recently, an ongoing randomized controlled trial began with the intent to define an ideal temperature in extended lung preservation. The study was designed to compare two randomized preservation protocols: a "4-10°C" arm that would extend up to 12 hours of cold ischemia, versus a "0-2°C" arm that would experience up to 6 hours of cold ischemia.8,9
 
However, investigation into these cited foundational studies reveals a discrepancy in the presentation of temperature measurements.
 
The temperature range of the storage environment - called the input - was reported. The output, representing the actual measured organ temperature, was not reported.
 
Other studies have similarly concluded that the optimal temperature is “in the vicinity of 10°C.” For example, the study methods by Wang et al. detail that “the storage temperature was kept constant by using a cold room at 4°C to 15°C” and that all storage environment temperatures are ±1°C (i.e., the temperature of “10°C” may actually range from 9-11°C).11
 
Nakamoto et al. came to a slightly different conclusion by using segmented regression models between functional parameters and preservation temperature.13 He stated that “the optimal temperature for lung preservation by topical cooling is 8°C to 9°C.”13
 
In all these presented clinical studies, the cited preservation temperatures were equated to the refrigerator's set temperature - not an actual measured temperature.   

THE REALITY?

The truth is quite simple: organ thermodynamics during hypothermic storage is complex. It is an oversimplification to conclusively state that a single fixed temperature is optimal.

DEBUNKING THE MYTH OF THE MAGIC NUMBER

A PRESERVATION WINDOW: UNITING ENGINEERING & PHYSIOLOGY
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View References List

  1. Kukreja et al., The 2024 American Association for Thoracic Surgery expert consensus document: Current standards in donor lung procurement and preservation. JTCVS 2024.

  2. An-Lies Provoost, et al. Lung transplantation following controlled hypothermic storage with a portable lung preservation device: first multicenter European experience, Frontiers in Cardiovascular Medicine, (2024).

  3. Laurens J Ceulemans, et al. Extended Ischemic Time (> 15 Hours) Using Controlled Hypothermic Storage in Lung Transplantation: A Multicenter Experience Running head: Extended Ischemic Time in Lung Transplantation, Journal of Heart and Lung Transplantation, (2024).

  4. Langer et al., ISHLT Presentation 2025, Data on file. Real-World Outcomes Using Controlled Moderate Hypothermia at 4-8°C for Lung Transplant: An Update from the GUARDIAN-Lung Registry. April 29, 2025, 5:18 PM - 5:22 PM, Ballroom B.

  5. Hartwig et al, ISHLT Presentation 2025, Data on file. Controlled Moderate Hypothermic Storage at 4-8°C for the Preservation of Donor Lungs from Donations after Circulatory Death. April 29, 2025, 4:30 PM - 5:30 PM, Poster Hall.

  6. Ceulemans et al., ISHLT Presentation 2025, Data on file. Lung Preservation at Controlled 4-8°C for Extended Criteria Donors Improves Outcomes After Transplantation. April 27, 2025, 3:00 PM - 3:08 PM - Ballroom B.

  7. Bush et al., ISHLT Presentation 2025, Data on file. Constant Airway Pressure Management System Leads to Improved Donor Lung Outcomes: Analysis of Ischemic Times >8 Hours. April 27, 2025, 4:42 PM - 4:50 PM, Rooms 302-304-306.

  8. Traferox Technologies (2025). XPort: Instructions for Use. Retreieved from https://traferox.com/wp-content/uploads/2025/07/CAR-910-0003-UM-Rev-1-XPort-Lung-Preservation-Solution-IFU.pdf.

  9. https://www.clinicaltrials.gov/study/NCT05898776.

  10. Ali A, et al. Static lung storage at 10°C maintains mitochondrial health and preserves donor organ function. Sci Transl Med. 2021 Sep 15;13(611):eabf7601.

  11. L. S. Wang, et al. The effect of ischemic time and temperature on lung preservation in a simple ex vivo rabbit model used for functional assessment. J. Thorac. Cardiovasc. Surg. 98, 333–342 (1989).

  12. H. Date, et al. In a canine model, lung preservation at 10 degrees C is superior to that at 4 degrees C. A comparison of two preservation temperatures on lung function and on adenosine triphosphate level measured by phosphorus 31-nuclear magnetic resonance. J. Thorac. Cardiovasc. Surg. 103, 773–780 (1992).

  13. K. Nakamotoet al. A study on optimal temperature for isolated lung preservation. Ann. Thorac. Surg. 53, 101–108 (1992).

  14. Cenik I, et al. Temperature Dynamics of Porcine and Human Lungs During Static Ice Storage: Ice Is Not 4 °C. J Clin Med. 2025 Mar 20;14(6):2127.

  15. Hoetzenecker K, et al. Prolonged Preservation of up to 24 Hours at 10 °C Does Not Impact Outcomes after Lung Transplantation. Ann Surg. 2025 Apr 1;281(4):664-670.

  16. Gil Barturen M, et al. Donor Lung Preservation at 10°C: Clinical and Logistical Impact. Arch Bronconeumol. 2024 Jun;60(6):336-343.

  17. Ali A, et al. Extension of Cold Static Donor Lung Preservation at 10°C. NEJM Evid. 2023 Jun;2(6):EVIDoa2300008.

  18. Abdelnour-Berchtold E, et al. Evaluation of 10°C as the optimal storage temperature for aspiration-injured donor lungs in a large animal transplant model. J Heart Lung Transplant. 2022 Dec;41(12):1679-1688.

  19. Ali A, et al. Static lung storage at 10°C maintains mitochondrial health and preserves donor organ function. Sci Transl Med. 2021 Sep 15;13(611):eabf7601.

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