Warm Ischemia Time in Liver Transplantation

Definition and Types of Warm Ischemia Time

Warm ischemia time in liver transplantation should be limited to less than 90 minutes to minimize complications and improve outcomes, as recommended by the American Association for the Study of Liver Diseases 1, 2
In liver transplantation, warm ischemia time can be divided into two main categories depending on the type of donation: donor warm ischemia time and recipient warm ischemia time, with donor warm ischemia time occurring in donation after circulatory death donors and generally defined as the time from extubation to cross-clamp 3
Donor warm ischemia time can be further categorized into agonal phase, which begins when blood pressure or oxygen saturation drops below certain thresholds, and is associated with increased complications in DCD liver transplantation 4, 3

Warm ischemia time exceeding 90 minutes is associated with decreased graft survival in patients with hepatitis C, according to the American Association for the Study of Liver Diseases 1, 5
True warm ischemia time longer than 20-30 minutes is associated with increased complications in DCD liver transplantation, as reported by the American Society of Transplantation 2, 6
Total warm ischemia time longer than 30-45 minutes is associated with increased complications in DCD liver transplantation, with a strength of evidence level of moderate, according to the American Society of Transplantation 2, 6

Time from incision to cross-clamp is the only surgically modifiable period to shorten donor warm ischemia time, and should be minimized to reduce complications, as recommended by the Clinical and Molecular Hepatology society 4, 3
Premortem heparin administration is used in over 90% of DCD donors to prevent thrombus formation, though this practice may be ethically controversial, according to the Clinical and Molecular Hepatology society 3
Ex vivo machine perfusion techniques are being investigated as potential strategies to mitigate the effects of warm ischemia, though these are currently considered investigational, with a strength of evidence level of low, according to the American Journal of Transplantation and the Journal of Hepatology 2, 7

Cold ischemia time should be kept under 8 hours and warm ischemia time should not exceed 90 minutes to optimize outcomes, as recommended by the American Association for the Study of Liver Diseases 1, 5
For DCD liver transplantation, cold ischemia time should not exceed 8-10 hours, as recommended by the American Society of Transplantation 2, 6
Expeditious, in situ biliary flush should be performed to minimize bile-induced epithelial damage in DCD liver donors, as recommended by the American Society of Transplantation 6
The use of DCD livers with longer ischemia times or from older donors should be limited to reduce the risk of biliary complications, as recommended by the American Society of Transplantation 6