Cold Ischaemia and Organ Preservation
Cold ischaemia time is the period from when a donor organ is flushed with cold preservation solution and packed on ice until it is reperfused in the recipient. Cold slows but does not completely stop cellular metabolism, and prolonged cold ischaemia causes a cumulative injury that reduces graft function and survival. Each organ has a different tolerance for cold ischaemia, reflecting its metabolic rate and sensitivity to ischaemia-reperfusion injury.
| Organ | Maximum Cold Ischaemia | Key Logistical Implication |
| Heart | 4–6 hours | Shortest tolerance — retrieval, transport, and implantation must be tightly planned. National coordination is critical. |
| Lung | 6–8 hours | Short tolerance; bilateral lung retrieval and transplantation is logistically demanding |
| Liver | 12–24 hours | Allows inter-regional and national sharing; DCD livers have shorter effective tolerance due to warm ischaemia |
| Pancreas | 12–24 hours | Similar to liver; usually shared with liver retrieval team |
| Kidney | 24–36 hours | Most tolerant solid organ — allows national and international sharing; machine perfusion can extend further |
| Small bowel | 6–12 hours | Limited tolerance; transplanted at very few specialist centres |
Machine perfusion — both hypothermic (HMP) and normothermic (NMP) — is increasingly used to extend preservation times, assess organ viability before transplantation, and recondition marginal organs. This technology is particularly valuable in DCD kidneys and livers, where the prior warm ischaemic injury makes viability assessment important before committing to transplantation.
| The ICU Clinician’s Organ Donation Responsibilities • Identify potential DBD donors early — refer to SNOD before brain stem death testing is complete • Identify potential DCD donors when withdrawal of treatment is being considered — refer to SNOD at that stage • Never unilaterally conclude a patient is unsuitable for donation — always discuss with SNOD • Separate the brain stem death conversation from the organ donation conversation • Actively manage the donor with the same care and attention as any other ICU patient • Follow the NHSBT Donor Optimisation Bundle systematically • Support and facilitate the SNOD’s involvement with the family |