26 March 2021

Are You Really Dead?

Welcome back. The doctor checks this and that, then pronounces you dead. Sorry, you’re not in any position to argue, but has the doctor waited long enough? Though I’ve blogged about Near-Death Experiences; this post doesn’t stop at near.

It’s over, you’ve died (photo from www.gdnonline.com/Details/363916).

A recent study examined the minimum duration of pulselessness after circulatory determination of death before organ donation may proceed. In short, how long must they wait? To avoid a damaged organ for transplantation, there’s a limited period of time after life-sustaining measures are withdrawn.

The work drew upon a team of more medical professionals than you could imagine from Canada, the U.S., Czech Republic, U.K. and the Netherlands.

Death and Organ Donation
The dead donor rule is the requirement that removal of vital organs cannot be the cause of the donor’s death and can take place only after death has occurred.

In accordance with Canada’s Criminal Code, for example, the dead donor rule cannot be waived by the donor; however, it is permissible to withdraw life-sustaining therapies and allow the underlying condition to bring about death naturally. 

Deciding when to withdraw life support (photo from theconversation.com).

Before the advent of mechanical ventilators, death was determined by lack of respiration and heartbeat. People who lost all brain function would stop breathing, and their hearts would stop beating. With ventilators it became possible to maintain respiration and heartbeat when the brain had irreversibly stopped functioning. This led to the idea of “brain death” and, in the late 1960s, the determination of death using neurological criteria.

Today, determination of death may be according to circulatory or cardo-respiratory criteria (cardiac death or circulatory death) or according to neurological criteria (brain death). Both determinations involve specific clinical criteria and tests.

Study Design
The researchers conducted a prospective observational study of vital signs--cardiac electrical and pulse activity--in adults that died after planned withdrawal of life-sustaining measures. In all, 631 patients were monitored in 20 intensive care units in 3 countries.

Bedside clinicians monitored the patients for 30 minutes after determination of death and reported resumption of cardiac activity. Continuous blood-pressure and electrocardiographic (ECG) waveforms were recorded and reviewed retrospectively to confirm bedside observations and identify additional instances of cardiac activity.

Cardiac Activity Post-Death
The bedside clinicians reported resumption of cardiac activity, respiratory movement, or both, confirmed by waveform analysis, in 5 of the 631 patients. Retrospective analysis of ECG and blood-pressure waveforms identified 67 instances of cardiac activity after pulselessness, including the 5 reported by bedside clinicians.

Most heart resurgences occurred within 2 minutes after the heart had stopped and were usually a single heartbeat or shorter than 5 seconds. The longest interval between pulselessness and resumption of cardiac activity was 4 minutes, 20 seconds.

Analysis of waveform signals after removing life support (from Death Prediction and Physiology After Removal of Therapy (DePPaRT) study video, www.youtube.com/watch?v=JQ5RtP7Ec9Y&feature=emb_title).
Wrap Up
The study demonstrated that the classic flatlining of death is not always, well, flat. Cardiac activity restarted and stopped several times before stopping completely, yet no patient in the study regained sustained circulation or consciousness.

Finding that the longest interval before resumption of cardiac activity was 4 min, 20 sec supports the current standard of waiting 5 minutes after the heart stops before pronouncing death and proceeding with organ donation.

By the way, don’t hesitate to register as an organ donor (in the U.S., check your state health department or see P.S. below). Thanks for stopping by.

Dead donor rule and death determination: cdtrp.ca/wp-content/uploads/2021/01/Fast-Facts-Death-Determination-FEB2021.pdf
Study of cardiac activity after withdrawal of life-sustaining measures in New England Jour. of Medicine: www.nejm.org/doi/full/10.1056/NEJMoa2022713
Articles on study on EurekAlert! and Live Science websites:
U.S. organ donor information: www.organdonor.gov/register.html

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