How is brain death defined?
Brain death is defined as the irreversible loss of all functions of the brain, including the brain stem. The three essential findings in brain death are coma, absence of brain stem reflexes, and apnoea(lack of breathing). An evaluation for brain death should be considered in Patients who have suffered a massive, irreversible brain injury of identifiable cause. A Patient determined to be brain dead is legally and clinically dead.
The diagnosis of brain death is primarily clinical. No other tests are required if the full clinical examination, including each of two assessments of brain stem reflexes and a single apnoea test, are conclusively performed.
Brain death is the irreversible end of all brain activity (including involuntary activity necessary to sustain life) due to total necrosis of the cerebral neurons following loss of brain oxygenation. It should not be confused with a persistent vegetative state. Patients classified as brain dead can have their organs surgically removed for organ donation. Even after brain death,the working of the heart and respiration might continue at a slow pace. Brain death, either of the whole brain or the brain stem, is used as a legal indicator of death in many jurisdictions.
Brain Death occurs as a consequence of a severe injury. This injury usually leads to hypoxia(lack of oxygen) in the brain and therefore the Patient’s brain has stopped working, resulting in a Patient’s respiratory arrest and cardiac arrest.
- How does a person become brain dead?
- What happens in Intensive Care?
- How is brain death diagnosed?
- Why does the Patient still appear alive?
- What happens when brain death is diagnosed?
- What are the implications of a Coronial investigation?
- Organ and Tissue Donation
How does a person become brain dead?
Direct head trauma or Traumatic Brain Injury (TBI) can cause bleeding in the brain, therefore reducing oxygen supply in the brain with an acute lack of oxygen. This leads to a rise in the intracranial pressure(pressure in the brain/skull) and swelling, causing unconsciousness and coma. Due to the rise of the intracranial pressure(ICP), a normal blood pressure can not supply the brain with sufficient oxygen, therefore leading to hypoxia(lack of oxygen) in the brain. Usually the brain can be without oxygen for up to 3-4 minutes without getting permanently damaged. The brain inside the skull has no room to move when trauma has caused swelling, therefore brain cells die and the brain stem can be pressed downwards through the elevated intracranial pressure. This scenario often leads to death, as the brain stem controls vital functions such as breathing, heart rate, temperature and our blood pressure.
What happens in Intensive Care?
- Your loved one is continuously monitored with a Bedside Monitors- Your loved ones Blood pressure is usually displayed continuously on the bedside monitor via an Arterial Catheter. Your loved ones Heart and Heart rhythm(ECG) is continuously monitored and displayed on the monitor. Oxygen levels are continuously monitored by an oxygen saturation probe attached to the finger or to the ear. Furthermore oxygen levels are intermittently checked with ABG’s(Arterial Blood Gases), where blood is drawn out of the Arterial line and tested immediately via a Blood Gas Analyser.
- Drugs for blood pressure control are often administered as an infusion via an infusion pump. This allows for strict blood pressure control. Blood pressure control may be necessary if your loved one is donating some of their organs
- Full ventilation using a Ventilators(Breathing Machine) and a Breathing Tube (endotracheal tube) will usually be required to improve the oxygen delivery
- If the initial injury has been caused by a Traumatic Brain Injury(TBI), Intracranial Pressure Monitoring(ICP monitoring) may be necessary to control the pressure in the skull and the brain
- Your loved one may be taken to theatre for temporary removal of a piece of skull to relieve the pressure caused by the swelling and insertion of a drain into the brain to monitor and relieve the pressure
- Despite all the efforts, Intracranial pressures are uncontrollable and your loved one may progress to become brain dead
- Usually hourly neurology observations are performed(check of pupils with torch)
- Usually signs of brain death are loss of respiratory efforts(breathing), loss of natural cough, loss of eye blinking and loss of pupil reaction to light
- Usually the Patient’s heart rate as well as their blood pressure diminishes once the brain is dead
- Further medical tests are performed if brain death is assumed
How is brain death diagnosed?
Usually, two senior Physicians(medical doctors) perform separate brain death tests at the bedside in order to determine if a Patient is brain dead or not.
They usually follow strict rules and strict guidelines for testing. The tests performed include testing the cranial nerves passing through the brain stem that control reflexes.
- responsiveness to pain stimuli
- responsiveness to light by the pupils
- blinking response when eyes are touched
- eye movement or response to ice cold water when rinsed through the ear canal
- cough, swallowing or gag when the back of throat is touched
- disconnection of Patient from ventilator to see whether there is any sign of breathing
Working through these tests rules out if there are other causes of the coma.
For a person to be declared brain dead they must not show any response to each and every one of these tests.
Some Patients may not be able to have all of these tests performed, depending on the nature of the injuries sustained. Spinal injuries, eye or facial injuries mean that nerves cannot be adequately tested. Special x-rays such as CT’s or MRI’s are done to check if there is any blood flow to the brain. The Patient’s time of death will be recorded at the time brain death was confirmed.
Why does your loved one still appear alive?
During this time in Intensive Care, while your loved one is kept ‘alive’ by the equipment in Intensive Care he or she will be warm and pink and their chest will be moving.
After brain death has been confirmed your loved one will remain connected to the ventilator until decided when ventilation is to be discontinued. Your loved one will have a heart beat as it has a natural pacemaker that works independently of the brain and will keep working at this time whilst it receives oxygen through mechanical ventilation. If mechanical ventilation is not stopped, even though your loved one is “brain dead”, your loved one will progress multi-organ failure over a period of hours to days and the heart eventually stops.
What happens when brain death is diagnosed?
When brain death has been confirmed by two senior doctors, usually a family meeting is held to discuss and confirm implications and the next steps. The care for your loved one should not change until after this meeting has taken place. In this meeting the question is asked whether they want to donate the organs of their loved one. If this is the case and the Family wants their loved one to donate their organs, your loved one will remain in Intensive Care for up to another 24 hours until organs are removed. For more information click Organ& Tissue Donation.
The other options for a family at this time is to stop the ventilation and allow the heart to stop. If your Family elects to have ventilation stopped without organ donation, usually the medical and the nursing staff discuss this process with you and your Family. This is the time for you to bring up your cultural and religious needs for your loved one if any and individualise the process. Once ventilation is ceased, the heart usually stops within minutes.
Of course, if you have any questions or concerns, please discuss them with the ICU nurses and doctors.
All Intensive Care interventions and procedures carry a degree of potential risk even when performed by skilled and experienced staff. Please discuss these issues with the medical and nursing staff who are caring for your loved one.
The information contained on this page is general in nature and therefore cannot reflect individual Patient variation. It is meant as a back up to specific information which will be discussed with you by the Doctors and Nurses caring for your loved one. INTENSIVE CARE HOTLINE attests to the accuracy of the information contained here BUT takes no responsibility for how it may apply to an individual Patient. Please refer to the full disclaimer.
- Understanding Brian Death and Organ Donation: Living beyond Loss. Australian & New Zealand Organ and Tissue Donation Agency
- www.organdonation.nhs.uk/ (UK tissue& organ donation)
- www.organdonor.gov/ (USA tissue& organ donation)
- www.donatelife.gov.au/ (Australian tissue& organ donation)