In organ transplantation, ischaemia may be described as cold or warm:
- Cold ischaemia corresponds to the period when grafts from brain-dead donors are placed at 4°C, while waiting to be re-implanted.
- Warm ischaemia corresponds to periods when:
- the organ is no longer perfused by the donor’s blood due to cardiac arrest or by clamping of the artery during collection;
- the organ is manipulated and exposed to the recipient’s body temperature during reconstruction of the vascular anastomoses.
Actors involved
Mechanism
Where?
In the harvested organ.
When?
From the removal of the organ, and until the reestablishment of the vascularisation of the organ, that is to say, its reperfusion.
How is this done?
Consequences
The first cells affected by ischaemia are endothelial cells, which:
- lose their cellular integrity and enter apoptosis. The endothelium therefore no longer fulfils its barrier function;
- activate and synthesise cytokines/chemokines , as well as expressing Class II HLA molecules and adhesion molecules, which will lead to the recruitment of inflammatory cells during reperfusion.
It is recommended that the cold ischaemia time does not exceed 20 hours for the kidney and 4 hours for the heart. Irreversible damage is observed when warm ischaemia exceeds 30 minutes.