Ischemia time

An ischemia period is the period during which an organ is not supplied with blood and thus not supplied with oxygen.

This period of time plays a decisive role in transplantation. It covers the period from the removal of the organ to reperfusion (Kuhlmann 2015).

The ischemia period is differentiated between two warm and one cold ischemia period (Kuhlmann 2015)

• warm ischemic period:
  • the 1st warm ischemia period comprises the time span of only a few minutes between stopping the blood flow and cooling the transplant to approx. 4 degrees Celsius
  • the 2nd warm ischemia period covers the time between the start of anastomosis and the release of blood flow

• cold ischemia time:

Cold ischemia time (often abbreviated as CIT [Krukemeyer 2008]) is the time between cooling of the graft and the beginning of anastomosis.

(Herold 2020)

The optimal ischemia time varies greatly for the individual organs.

• Kidney:
  • cold ischemia time < 20 h ( suboptimal up to > 36 h)
• liver:
  • cold ischemia time < 10 h (suboptimal to > 10 h)
• heart:
  • cold ischemia time < 4 h (suboptimal > 4 h)
• lung:
  • cold ischemia time < 8 h (suboptimal > 8 h) (Krukemeyer 2008)

The functional assessment of the transplant depends - in addition to donor factors, such as the functional status of the kidneys, the age of the donor, etc. - (Angstwurm 2013), whereby the warm ischemic period plays a greater role.

A warm ischemia time of e.g. 30 min. causes greater tissue damage to the organ and also delayed organ function than a cold ischemia time of > 24 h (Wüthrich 2013).

However, the ischemia time is also of crucial importance for the long-term success of a transplantation.

This is taken into account in the allocation of a donor organ by Eurotransplant in the form of additional points (Bundesärztekammer 2013):

• 200 points if the removal of the donation and the implantation can take place in the same region
• 100 points if the collection of the donation and the implantation can take place in the same country
• 0 points if the collection of the donation and the implantation took place in different countries

In the case of a kidney transplant, for example, acute tubular necrosis can occur, among other things, as a result of a long cold ischemia period of > 30 h or a long warm ischemia period (more precise details are not available). This occurs in 19 % of all postmortem transplantations (Hoffmann 2014).

In order to keep the cold ischemia period as short as possible, a selective angiography of the renal vessels should be performed preoperatively on the potential donor in order to be informed about any anomalies (Kasper 2015).

1. Angstwurm H et al (2013) Guidelines on organ transplantation according to § 16 Transplantation Act. German Medical Journal (97) A 396 - A 411
2. German Medical Association (2013) Guidelines for waiting list management and organ procurement for kidney transplantation according to § 16 para. 1 p. 1 nos. 2 and 5 TPG
3. Herold G et al (2020) Internal medicine. Herold Publisher 647
4. Hoffmann G F et al (2014) Pediatrics: Principles and practice. Springer publishing house 204
5. Kasper D L et al (2015) Harrison's Principles of Internal Medicine. Mc Graw Hill Education 18 27
6. Kasper D L et al (2015) Harrison's Internal Medicine. Georg Thieme Publisher 2248
7. Kuhlmann U et al (2015) Nephrology: Pathophysiology - Clinic - Kidney replacement procedure. Thieme publishing house 766, 770
8. Krukemeyer M G et al (2008) Transplantation Medicine: A Guide for the Practitioner. de Gruyter Publishers 83 - 85
9. Wüthrich R P (2013) Kidney Transplantation: Basics, Pre- and postoperative care, long-term monitoring. Springer Publishing House 83