Until relatively recently the definition of death was a cessation of breathing and the absence of a pulse (Dimond, 2004). However, artificial ventilation can now maintain respiratory function, external chest compressions can maintain circulation and cardiac defibrillation can restore the heart to a functioning rhythm. This means that people who would previously have been considered dead are now seen as being in need of urgent medical attention, which can result in them being kept alive only by artificial ventilation.
VOL: 102, ISSUE: 13, PAGE NO: 28
David Gallimore, MSc, BSc, RGN, is tutor in adult nursing, School of Health Science, University of Wales, Swansea
The areas of the brain required to stimulate breathing have died but the heart continues to beat. This has led to the development of the diagnosis of brainstem death.
Anatomy of the brain
In order to understand the importance of the brainstem to the normal functioning of the body it is essential to examine the location and function of this part of the brain. The brain is an organ that is composed primarily of nervous tissue. It can be divided into a number of different areas that perform specific functions in the control of the body.
The largest part of the brain, at approximately 85% of the total weight, is the cerebrum. This folded structure, which is visible when the top of the skull is removed, controls the higher body functions - thought, emotion and language.
The brainstem is much smaller, found at the base of the brain, and is the anatomical link between the spinal cord and the rest of the brain. Its main function is to control the vital functions of the body. Specific areas within it control body temperature, blood pressure and breathing. The brainstem is also responsible for coordinating swallowing, coughing, sneezing, eyeball movement and the maintenance of consciousness (Tortora and Derrickson, 2006).
Damage to the brainstem will affect its functions - severe damage can cause a complete loss of activity in this area. The most immediately important consequence of this will be the inability to breathe. The other immediate impact will be loss of consciousness and coma. Loss of the other brainstem functions will only cause problems over time.
The heart will continue to beat, maintaining circulation and a certain level of blood pressure because the nature of cardiac tissue means the heart can continue to beat without external stimulation. The main role for the brainstem is to alter heart rate and blood pressure in response to changed demand. As the person is unconscious and immobile, demand will not normally change. If it does, for example through blood loss, the heart may no longer be able to maintain an adequate circulation (White, 2003).
The other major change that will occur as a result of damage to the brainstem is a blocking of nervous impulses passing through this region of the brain. This means information travelling up the spinal cord cannot pass through the brainstem to reach the other areas of the brain, such as the cerebrum. Also, the brain is unable to send messages back down the spinal cord to the body.
Damage to the brainstem can occur because of a transient condition within the skull. For example, oedema and swelling of the brain will cause the brainstem to be squashed into the base of the skull. This will cause a temporary loss of function in this section of the brain, which could potentially be reversed by a reduction of the swelling (Eelco and Wijdicks, 2001).
Brainstem death has been defined as ‘permanent functional death of the brainstem’ (Eynon, 2005). The important thing about this diagnosis is the irreversible nature of this change to the brain. Patients are only diagnosed as brainstem-dead when there is overwhelming evidence that there will be no reversal of their condition.
In adults the most common causes of brainstem death are traumatic brain injury and subarachnoid haemorrhage (Wijdicks, 1995). It can also be the result of indirect causes such as anoxia in drowning or asphyxiation, or ischaemia following blood loss or cardiac arrest.
It is important to note that patients who are diagnosed as brainstem-dead may not appear to be dead because the drugs they are given to maintain blood pressure keep their skin pink and warm, while the ventilator will cause the chest to rise and fall (Edwards and Forbes, 2003). It is also possible that their limbs may move in response to stimuli (Saposnik et al, 2005). This can be distressing for relatives and it is an important role of the nurse to provide support and explain the condition and prognosis.
Diagnosis of brainstem death
In the 1950s a number of medical and technical advances resulted in the survival of patients with severe illness who would previously have died. One of the main advances was the development of mechanical ventilation. This sometimes led to a complete recovery but sometimes the patient remained in a comatose state. This condition was first written about in 1957 by two French physicians, Mollart and Goulon, who had observed 23 patients in a state they described as ‘beyond coma’. These patients had signs and symptoms that might now lead to a diagnosis of brainstem death. They were in an irreversible coma with loss of consciousness, had no brainstem reflexes, could not breathe without the assistance of artificial ventilation and had a flat electroencephalogram (Eynon, 2005). The relevance of these observations was not fully appreciated for another decade.
Around this time other medical advances in surgery and immunosupression made organ transplantation possible and in 1967 Christiaan Barnard performed the first heart transplant (Machado, 2005). To succeed, these procedures required an organ donor to have a functioning cardiovascular system until the organs were harvested, which resulted in accusations that hearts were being removed from living people and led to the first definition of brainstem death in 1968 by a committee of the Harvard Medical School. This relied on a series of tests or criteria to establish that further treatment for the patient would be futile (Pittard, 2005). The definition has been refined in the US and similar guidelines have been introduced in other countries. For example, in the UK, the Conference of Royal Colleges and their Faculties published a statement on the diagnosis of brainstem death in 1976, which has been subject to continued modification and refinement ever since.
The tests used to establish brainstem death vary between countries (Eynon, 2005) and even within countries (Powner et al, 2004). It is not within the scope of this article to provide a detailed description of current UK practice but a summary of the tests used is presented in Table 1, p29. This is based on the most recent UK guidelines (Intensive Care Society, 2004). In the UK they are performed by doctors who are adequately experienced in this field of medicine but are not part of the transplant team.
Prior to any tests being performed a number of preconditions must be considered. First, the patient must be in a state of coma with no response to external stimuli and unable to breathe spontaneously. The patient’s condition must be unlikely to improve over time and there should be no other potentially reversible causes for the patient’s coma, such as severe hypothermia or correctable metabolic disorders. Finally, the patient must have no drugs in their circulation that could affect the test results, such as anaesthetic or depressant drugs (narcotics, hypnotics or tranquilisers).
The tests are performed by two doctors to help reduce observer error, and are usually repeated in case there is any change in the patient’s condition. If both sets of tests show death of the brainstem, and both doctors are in agreement with that diagnosis, the patient is declared dead. The time of death is recorded as that following the completion of the first set of tests, not the second. After this diagnosis ventilatory support can be withdrawn or, with the consent of the relatives, arrangements can be made for the patient to donate organs.
Although these tests are performed by doctors, nurses have a responsibility to ensure that the established guidelines are correctly followed. A nurse should also act as the patient’s advocate to raise any concerns they may have about the practice and procedure of the test.
There should also be consideration about the terminology when discussing the patient’s condition with relatives. The term ‘brainstem death’ should only be used in relation to potential testing or an established diagnosis of this condition. The term should not be used to describe a patient with severe brain injury who has not been tested for this specific condition. ‘Brainstem death’ has been incorrectly used to describe severe brain injury with a poor prognosis, often without brainstem tests being performed, and is often used to justify the withdrawal of treatment to relatives (Sundin-Huard and Fahy, 2004).
There is often some concern, especially from relatives, that the tests cannot determine whether the damage to the brainstem is irreversible. They are concerned that if support continues the patient may recover. The UK medical profession has decided that the concept was clearly defined in a study performed in the 1980s. This looked at patients who had been diagnosed as brainstem-dead but who had not had organs removed. The trial considered 1,300 patients, all of whom died within a relatively short period of time, usually a few days, from loss of cardiovascular function (Pallis, 1987). This demonstrates that the cardiovascular system can function for a time without the control of the brainstem but this is limited and regulation eventually fails.
The legal and ethical perspective
Although clinical guidelines have been developed to define brainstem death, they have not been incorporated into legislation, which means the diagnosis is not a legal definition of death. However, Dimond (2004) points out that it has been recognised in a number of court cases. The first was the case of a 19-month-old child who had been diagnosed as brainstem-dead. The doctors felt that to continue with this child’s care would be futile as there was no chance of recovery, and an appeal was made to a court to have the child removed from the ventilator. The judge recognised that the child was dead and furthermore decided that the time of death was when the doctors had first performed the brainstem death tests. This established the validity of the medical Royal Colleges’ guidelines for the tests of brainstem death in law. It also established the principle that removing patients with the diagnosis from ventilation would not be killing them as they were already dead.
There has been some concern about the ethical reasons for diagnosing a patient as brainstem-dead. Sundin-Huard and Fahy (2004) suggest that the only reason for testing a patient for brainstem death is to provide a source of donor organs. It is not until the patient has been diagnosed as brainstem-dead that the issue of organ donation can be considered. They suggest that ventilator and cardiovascular support can be withdrawn from a patient if doctors are convinced that to continue with treatment would be futile. This, they suggest, is ethically questionable and may be deceiving relatives who believe the diagnosis of brainstem death will be for the benefit of the patient. However, the previously mentioned legal cases do suggest there is a role for the diagnosis of brainstem death in deciding on the withdrawal of treatment.
Each week Nursing Times publishes a guided learning article with reflection points to help you with your CPD. After reading the article you should be able to:
- Understand the normal functioning of the brain;
- Understand the changes that occur in brainstem death;
- Appreciate the tests that are performed to diagnose brainstem death;
- Consider the legal and ethical consequences of brain death.
Use the following points to write a reflection for your PREP portfolio:
- Detail where you work and how this article is relevant to your practice;
- Outline the last time you encountered a patient with brainstem death;
- Identify a new piece of information about brainstem death that you have learnt from this article;
- Describe how this information may help in your future practice;
- Explain how you might disseminate this information to your colleagues.
This article has been double-blind peer-reviewed.
For related articles on this subject and links to relevant websites see www.nursingtimes.net.