Brain Death – What Is It?

We are all too familiar with cardiac death. It’s medical definition of irreversible cessation of circulatory and respiratory functions, since this is more common. Though Brain Death is defined medically as death, we hardly understand what it is about. And the main struggle in accepting such death is mainly due to the ability to use mechanical ventilators to support the other vital function for a long period of time. In addition, many would worry mis-diagnosis of such form of death for the purpose of organ donation. As such, it is difficult for one to accept the love ones to be proclaimed as ‘Dead’.

In Singapore, the Human Organ Transplant Act (HOTA) has allowed for the kidneys, liver, heart and cornea to be recovered in the event of death from any cause for the purpose of transplantation since 1 November 2009. And only patient with brain dead are illegible for this purpose. There is a good medical reason for this which we will discuss later. This topic arises my awareness due to my Dad who was in a dilemma on whether to opt out a not. His worry is mainly whether he will experience pain while his organs were removed. Moreover he heard stories of patients in US who were pronounced brain death were back to life. Is this a myth? Are our various concerns or rather worries unduly? I felt the need to understand more about this topic and so my search began.



What is Brain Death?


Brain Death is defined as the irreversible cessation of brain function. And so what does this mean to someone who is not medically trained in anyway. In simple term, the brain has stop functioning and is no longer sending signal to other part of the body. As such, the body stop functioning and the patient is dead.

Some possible causes of brain death include:

  • Trauma to the brain (i.e. severe head injury)
  • Cerebrovascular injury (i.e. stroke)
  • Brain tumor



Criteria for Brain Death?


Per JAMA (The Journal of the American Medical Association) published in March 18, 2009—Vol 301, No. 11, the clinical criteria are defined as:

  • No response to any stimulus—no movement, withdrawal, grimace, or blinking
  • No breathing efforts when taken off the ventilator (the apnea test)
  • Pupils dilated and not responsive to light
  • No gag reflex, no corneal reflex (blinking when the surface of the eye is touched), and absence of other specific reflexes

The above mentioned is pretty similar to the criteria for pronouncing a cardiac death.

There is a list of test (examination-based clinical criteria) the physician will perform. First the pyhsician will check to see if the patient flinches in response to something that can cause pain, like pinching the skin. Next shines a light in the eyes to check for pupil dilation and  tickled the vocal chord to check for  coughing or gagging response.

And JAMA has listed some other tests that the doctors may be used along with the examination-based clinical criteria. Not all tests need to be used to declare brain death. It differs from country.

  • Computed tomography (CT) scans of the brain may show abnormalities such as bleeding (hemorrhage), massive stroke, brain injury, or severe brain swelling (edema).
  • Electroencephalography (EEG) records electrical brain activity. If brain death is present, the EEG will show no activity.
  • Cerebral radionuclide injection shows no uptake of the radioactive material in the brain when a person is brain dead.

If you are interested to know the list of possible clinical examination that may perform, there is a list published in Indian J Crit Care Med. 2009 Jan-Mar for the purpose of educating the physicians in India on determining Brain Death. Click here to read on.



Coma Versus Brain Death


The general public are confused with Coma and Brain Death. We tend to lump them together and believe that they are referring the same.

Clinically, there is a list of criteria to diagnose one as in Coma versus Brain Death. In short the patient who is in Coma is with body function but is unconscious. The most obvious observation is hair and nail growth. And the patient will continue to produce urine and bowel.



Why Only Brain Death Patients Are Able To Donate Their Organ?


The heart has the ability to beat independently of the brain when oxygen is presence. When the breathing machine is not on, the heart will eventually stop beating too as the oxygen in the body will deplete since the patient no longer breathe on their own.

With the breathing machine, oxygen is provided to the organs until they were recovered for transplant. The machine is not keeping the patient alive, but merely keeping the organs viable.





From the death criteria of brain death versus cardiac dead, they are very similar. Basically, as long as the patient no longer can breath on their own, pupil no longer response to light, these are sign of death. In addition, a comprehensive testing were carried out by doctor before determining brain death. We have to remember that coma and brain death are totally different. Life exist in the former but not the latter. There is lots of myth and incorrect understanding about brain death in the general public. Therefore I see that there is a gap in education as well.





Live On Support Organ Donation. Found in

Understanding HOTA. Found in

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Kerridge IH1, Saul P, Lowe M, McPhee J, Williams D. Death, dying and donation: organ transplantation and the diagnosis of death. J Med Ethics. 2002 Apr;28(2):89-94.

Steven Laureys. Death, unconsciousness and the brain. Nature reviews Neuroscience (Impact Factor: 31.38). 12/2005; 6(11):899-909.

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Linda L. Emanuel, MD, PhD; Frank D. Ferris, MD; Charles F. von Gunten, MD, PhD; Joshua M. Hauser, MD; Jamie H. Von Roenn, MD. The Last Hours of Living: Practical Advice for Clinicians. Medscape Internal Medicine. March 24, 2015

Janet M. Torpy, MD et al. Brain Death. The Journal of the American Medical Association B.  March 18, 2009—Vol 301, No. 11.

Calixto Machado. Diagnosis of brain death. Neurol Int. 2010 Jun 21; 2(1): e2.