The Effect of Donor Transportation on the Function of Donor’s Organs

Background: The impact of donor transportation on the outcome of deceased organ donation remains largely unknown. This study aimed to investigate the effect of donor transportation on the function of the donor’s organs. Methods: From 2016 to 2018, 139 donors of successful deceased organ donation from the local (primary) hospitals transferred to our hospital were included for analysis. Blood samples were drawn immediately after the donor admitted to our hospital (pre-transport data) and before donation (post-transport data) to assess the donor’s organ functions by determining the levels of blood biochemical indexes. Results: The donor with a transport distance >200 km had higher post-transportation AST and a bigger change of TB level as compared with those with a transport distance < 200 km. Pearson’s correlation analysis showed a positive correlation between transport distance and post-transport AST. The donors with cardiac arrest history had signicantly higher pre-transport AST, pre-transport ALT, post-transport ALT, post-transport BUN, and the change level of BUN after transport as compared with those without cardiac arrest history. The donors with a history of cranial decompression surgery had signicantly lower pre-transport AST, pre-transport ALT, and post-transport Cr as compared with those without a history of cranial decompression surgery. Conclusion: These results suggested that long-distance donor transportation may result in organ function deterioration, especially for donors with a cardiac arrest history. Donors with a history of intracranial decompression surgery can alleviate this problem.

Organ transplantation is a highly effective treatment for the end-stage failure of most essential organs, but organ shortage remains the greatest limiting factor to organ transplantation [1]. Various approaches have been adopted to address the problem of organ shortage, such as living organ donation [2], paired donor exchange [3], donation after circulatory death [4], and expanded criteria donors [5]. However, little attention has been paid to the donated organ damage and wastage caused by the donation process.
The majority of donors of deceased organ donation in our hospital are from the local (primary) hospitals.
The donors or/and their families have organ donation wishes in local hospitals and the donors are transferred to our hospital for organ procurement. In clinical practice, however, a small proportion of donors died during or after transportation and ultimately failed to complete the organ donation. This loss undoubtedly aggravates the problem of "organ shortage". On the other hand, of the successful donation cases, there are some cases of emergency donations that fail to complete the pre-donation assessment and may pose a health risk to organ recipients.
Although previous studies have reported the relationship between long-distance transportation of grafted organ and graft outcome [6][7][8][9][10][11], nevertheless, the impact of donor transportation on the outcome of deceased organ donation remains largely unknown. Therefore, the purpose of this study was to investigate the effect of donor transportation on the function of the donor's organs.

Study subjects
This was a retrospective study. The inclusion criteria were: 1) the donors of deceased organ donation from the local (primary) hospitals transferred to our hospital for organ procurement; 2) all deceased organ donation cases were supervised by the organ procurement organization and the Guangdong Provincial Red Cross Society. The exclusion criteria included: 1) donation was terminated due to the willingness of the family after the start of the donation process; (2) the donation cases had no transfer process. From 2016 to 2018, 139 donors of successful deceased organ donation were included for analysis. The distance between the local hospitals to the authors' hospital mainly ranges from 150-350 km. This study was approved by the institutional review board (IRB) of our hospital and written informed consent was waived by the IRB due to the retrospective nature of this study. The Declarations of Helsinki and Declaration of Istanbul guidelines are followed and that no executed prisoner was used as a donor.

Data collection
Donor's organ functions were assessed by blood biochemical indexes. Blood samples drawn immediately after transfer to our hospital were used for determining the pre-transport data, while the last blood draw before donation (approximately 24-48 hours after completion of transfer) was for the post-transport data. The blood biochemical indexes included aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TB), sodium (Na), blood urea nitrogen (BUN), creatinine (Cr).

Statistical analysis
Continuous data were indicated with mean ± standard deviation (SD). For the comparisons between two groups, the student's independent t-test or Mann-Whitney U test (if normality was not assumed) was used. donations, 107 (80.45%) cases were donation after cardiac death (DCD) while 26 (19.55%) cases were donation after brain death (DBD). The major causes were cerebrovascular accident (59.71%), followed by traumatic brain injury (30.94%). The mean transport distance before transplantation was 177.64±99.66 kilometers (range: 5 to 375.9 km). There were 12 (8.63%) cases undergoing emergency procurement, 23 (16.67%) cases with a history of cardiac arrest, and 61 (44.20%) cases receiving cranial decompression surgery before donation.

Subgroup analysis strati ed by transportation distance
To investigate if transportation distance had an impact on the laboratory indexes, donors were dichotomized into the >200 km group and <200 km group according to their transportation distance. The results showed that the >200 km group had higher post-transport AST (67.00±45.19 vs. 143.42±212.50, P=0.021, Table 2) and bigger change of TB level (0.73±14.72 vs. 6.34±13.35, P=0.048, Table 2). The distribution was also demonstrated in scatter plots for ATS ( Figure 1) and TB ( Figure 2). Pearson's correlation analysis showed a positive correlation between transport distance and donors post-transport AST (Pearson's correlation coe cient r=0.2, P=0.045).

Subgroup analysis strati ed by cardiac arrest history
Subgroup analysis of clinical characteristics was conducted to compare between donors with and without cardiac arrest history. As shown in Table 3 [11]. However, the in uence of donor transportation on the outcome of deceased organ donation remains to be elucidated.
In this study, we investigated the effect of donor transportation on the function of the donor's organs. The results showed that the donor with a transport distance >200 km had higher post-transportation AST and a bigger change of TB level as compared with those with a transport distance < 200 km. Pearson's correlation analysis showed a positive correlation between transport distance and post-transport AST. AST and ALT are enzymes found mainly in the liver, red blood cells, heart cells, muscle tissue, pancreas and kidneys, and can be released into the blood by the injured liver or muscle cells and are used as indicators for injury of these organs [14]. TB is a biomarker for liver disease [15]. Thereby, these results suggested that long-distance transportation may lead to unstable vital signs of the donors, which should be attributed to the bumps during transport.
Subgroup analysis showed that the donors with cardiac arrest history had signi cantly higher pre-transport AST, pre-transport ALT, post-transport ALT, post-transport BUN, and the change level of BUN after transport as compared with those without cardiac arrest history. BUN is a marker for kidney function [16]. Elevation of the BUN level suggests kidney disease and increased risk of cardiovascular events in patients with acute heart failure [17]. Therefore, this result suggested that donors with a history of cardiac arrest had a greater risk of organ damage after transportation as compared with those without a history of cardiac arrest, which may be attributed to the instability of vital signs caused by the bumps during transport.
Our subgroup analysis also revealed that the donors with a history of cranial decompression surgery had signi cantly lower pre-transport AST, pre-transport ALT, and post-transport Cr as compared with those without a history of cranial decompression surgery. Serum Cr is also a commonly used marker of kidney function [18]. Since most of the donors had a cerebrovascular accident or traumatic brain injury, intracranial pressure may be increased during transportation, causing unstable vital signs and increased organ damage. However, the craniocerebral decompression surgery may alleviate the increased intracranial damage caused by the bumps during transportation.
In clinical practice, some donors had unstable vital signs during transportation, and the transportation team had recommended that urgent organ procurement should be implemented. Therefore, as soon as the donor arrived, the transplant team quickly completed the preoperative preparation and performed organ procurement to avoid organ wastage. Therefore, organ damage caused by transportation is sometimes inevitable, and establishing a transportation team with professional critical illness assessment and the well communication among different departments can also avoid organ wastage caused by transportation.
Several limitations to this study should be pointed out. Theoretically, the pre-transport data should be based on the blood samples drawn in the local hospital immediately before the transport, however, it cannot be achieved. Therefore, the blood samples drawn immediately after transfer to our hospital were used for determining the pre-transport data. In addition, although we found some signi cant differences in the posttransport data in our intergroup comparison, however, there were no signi cant differences between the pretransport and post-transport data. Including the non-transport donors as a control group allows a more comprehensive assessment of the impact of donor transportation. Moreover, this study did not analyze the postoperative recovery of the recipient, thereby it could not provide stronger evidence to support our ndings. In the future, a well-designed study with a large sample size should be conducted to validate the ndings of this study.

Conclusions
In summary, our results suggested that long-distance donor transportation may result in organ function deterioration, especially for donors with a cardiac arrest history. Patients with a history of intracranial decompression surgery can alleviate this problem. Donor transportation should be avoided and the grafted organs should be procured at the local hospital after complete assessment as much as possible.
Abbreviations ALT: alanine aminotransferase; AST: aspartate aminotransferase; BUN: blood urea nitrogen; Cr: creatinine; DBD: donation after brain death; DCD: cardiac death; SD: standard deviation; TB: total bilirubin Declarations Ethics approval and consent to participate This study was approved by the institutional review board (IRB) of the Third A liated Hospital of Sun Yatsen University.
Written informed consent was waived by the institutional review board (IRB) of the Third A liated Hospital of Sun Yat-sen University due to the retrospective nature of this study.

Consent for publication
Not applicable.

Availability of data and materials
All data generated or analyzed during this study are included in this published article.

Competing interests
The authors declare that they have no competing interests.    Figure 1 Scatter plot between the change in TB level and transportation distance by continuous distance (A) and distance groups (B).

Figure 2
Scatter plot between post-transport ATS level and transportation distance by continuous distance (A) and distance groups (B).