A new international study in New England Journal of Medicine, documents the physiology of the dying process. More than 600 families were asked to allow their loved ones in the ICU to have vital signs monitored during the dying process.
The researchers found that the classic "flatline" of death is not so straightforward. The study showed that cardiac activity often stops and re-starts several times during the dying process before it finally stops completely - although no one in the study regained sustained circulation or consciousness.
Amongst 480 patients, 67 (14%) of them resumed cardiac activity after a period of pulselessness. The longest duration after pulselessness before resumption of cardiac activity was 4 minutes, 20 seconds.
The study provides evidence to support the current standard to wait for 5 minutes after the heart stops before determining death and proceeding to organ donation.
Confirmation of the current standard is important. For families to choose organ donation when a loved one has died, they must be able to trust that death has really happened and that it is irreversible. Trust allows people to decide to donate at a time of grief and allows the medical community to feel comfortable opening a dialogue about donation.
For donation after circulatory-determined death to be medically possible, death must be declared within a window of time after life sustaining measures are withdrawn. Yet stories persist about people "coming back to life" following a declaration of death, and up to now there has been little evidence to inform the medical understanding of dying.
Further work using the study data will allow donation and transplant teams to predict how long it will take patients to die after removing life-sustaining measures. Predicting a time of death would be immensely useful to coordinate donations and to improve how organs are allocated.
Michael Cook is editor of BioEdge
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