Resuscitation (Casualty Surgeons Association Papers), 5, 49-52
Irrecoverable brain damage after resuscitation: brain death and other syndromes B. JENNETT University Department of Neurosurgery, Institute of Neurological Sciences, Glasgow G5I 4TF. Scotland
Resuscitation procedures are now so widely available in hospital that many patients with cardiac or respiratory arrest are intubated and ventilated as a routine primary measure. By then cardiac function will often be restored and sometimes respiration also. In patients who are still apnoeic but with good heart action, and in whom primary respiratory arrest is presumed, the problem is to discover whether the cause for this is reversible - such as depressant or relaxant drugs, or compression of the brain stem by an intracranial mass that can be removed. If spontaneous breathing returns then resuscitation has proved lifesaving, although the patient may have suffered some degree of irrecoverable brain damage. Should the patient remain apnoeic after the cause of the initial crisis has been investigated and treated then the question of brain death arises. In either event the degree of brain damage should be assessed as soon as possible, so that a decision can be reached about whether life-support measures should be maintained. If primary resuscitation is to become a routine reaction to cardiorespiratory arrest in hospital, then it must become commonplace also to withdraw support once it is obvious that the patient cannot recover. Unless this becomes established as good medical practice there may be increasing reluctance to embark on resuscitative measures. It is sometimes possible to anticipate cardio-respiratory collapse in a patient with an irrecoverable intracranial or extracranial disease process, and to issue prior instructions not to resuscitate. More often the crisis occurs before the nature of the primary disease process has been fully established; those at the bedside, nurses or junior medical staff, have then little option but to resuscitate in order to provide time for a decision to be made as to whether the situation is reversible. There are two reasons why the question of continued support should be considered as soon after resuscitation as possible. One is to avoid deploying the resources of intensive care on patients who are irretrievable for any longer than is necessary. The other is to facilitate organ donation, if this should be appropriate (Forrester, 1976). Brain death This term applies to patients whose respiration has irreversibly ceased owing to irremediable structural brain damage, but in whom the circulation is still adequate because artificial ventilation is being maintained. Had this not been instituted the heart would have stopped soon after the respiratory arrest, from systemic hypoxia. Even if all support is continued there will be progressive dissolution of internal organs in such patients, beginning with the brain; and the heart will continue to beat for only a few days at the most. Before applying criteria for the diagnosis of brain death it is important to ensure that irreversible structural brain damage is in fact the reason for the patient being in coma and apnoeic. The 49
50
B. JENNETT
best evidence for this lies in the clinical history of head injury or of sudden collapse due to intracranial haemorrhage or ischaemia. The latter may be secondary to cardiorespiratory arrest, from heart disease or a complication of anaesthesia or some other hospital procedure. In these cases, and when a patient is found unconscious at home or in the street, the question of drugs causing or contributing to the patient’s state arises. Because drugs may produce reversible suspension of brain activity it is most important to exclude their influence, as far as possible. Toxicological surveys are impractical - the state may result from a combination of several drugs (including alcohol), none of which may be present in toxic doses. The other cause of reversible brain failure is hypothermia, again likely only when patients are found after exposure to low ambient temperatures. BRAIN DAMAGE 1 COMA c IRRECOVERABLE NO BRAIN-&EM
FUNCTION
& RECOVERABLE
4 NO CORTICAL FUNCTION
No respiration
Spontaneousrespiration
No brain-afem reflexes 1 BRAIN DEATH
Some brain-stem reflexes 1 PERSISTENT VEGETATIVE
Heart stops in days
May live weeks, months 01 years
STATE
FULL RECOVERY
Criteria for brain death are best limited to clinical features which can be elicited by doctors in any hospital, and which do not depend either on specialists or on laboratory tests which are not generally available. It is first necessary to confmn that the patient is still apnoeic, by watching for spontaneous respiration during 5 min off the respirator; oxygenation can be satisfactorily maintained by delivering oxygen via a catheter in the endotracheal tube. During this period the Pa,coz should rise to values well above the threshold for stimulating the respiratory centre provided that it is 36 mmHg at the beginning. If there is doubt about this an adequate carbon dioxide level can be assured by ventilating with S% carbon dioxide before disconnection. Brain-stem reflexes should all be absent. The pupils should be fixed to a bright light (size is irrelevant); there should be no facial, corneal or gag responses to stimulation. The oculo-vestibular reflexes should be absent, with no eye movement during or after the slow injection of 20 ml of ice-cold water into each external auditory meatus, clear access to the drum having been established on both sides. Spinal cord function may be preserved for some time after brain death, and reflex movements of the limbs may then persist. Thk laboratory test most often invoked is the EEG, and in various countries EEG societies have stipulated conditions which must be satisfied before a flat or silent record is reported. The high standard of recording required, together with the weight of the decision which depends on it, puts an unfair responsibility on recordists; artifactual activity from various sources, which are difficult to eliminate in the busy intensive care unit, frequently lead to doubt being expressed and a request for a repeat recording next day. The result is that patients who are clearly ‘brain dead’ by clinical criteria may be needlessly maintained on ventilation, to the distress of relatives and staff, and to the detriment of possible organ donation. Because of this, and the restricted availability of EEG facilities, it is increasingly recommended that brain death criteria should be adopted which do not depend on the EEG; this may, however, be used in occasional cases of
CASUALTY
SURGEONS ASSOCIATION
PAPERS
51
unusual difficulty. The other laboratory measures sometimes recommended are even less readily available - cerebral angiography, isotope estimations of blood flow or measures of cerebral arteriovenous oxygen difference. Codes of practice for diagnosing brain death commonly require that criteria be shown to persist for a certain period of time. Earl Walker (1976) has recently pointed out that calling for re-examination over periods of 6-24 h probably represents ‘overkill’and is unduly restrictive. His suggestion is that two examinations 30 min apart, 6 h after the cerebral insult, would seem a practical one for most cases. But there are patients in whom it is clear much sooner than 6 h that no more can be done; unless the question of organ donation arises, which may call for various arrangements to be made, there would then seem no need to delay discontinuation of ventilation.
Apnoea associated with consciousness
Respiratory paralysis and inability to move may result from polyneuritis, poliomyelitis or myasthenia gravis, and such patients may survive for long periods if artificial ventilation is maintained. They are conscious and some or all of the brain-stem reflexes will be present so that confusion with brain death should never occur. More difficult are the rare cases of survival after vascular lesions affecting the ventral pontine region (brain-stem stroke). In these patients the lower brain-stem reflexes are lost but eye movements and eye-lid blinking are preserved, so that some patients learn to communicate by a code which uses this remnant of voluntary movement. This is the state described as the ‘locked-in’ syndrome.
Persistent vegetative state
This describes the patient who is breathing spontaneously, but who remains unresponsive and speechless. No psychologically meaningful response can be elicited because the cerebral cortex is functionally inactive - either because neocortical necrosis has resulted from systemic hypoxia or ischaemia, or because the cortex is disconnected from brain-stem arousal centres by extensive white-matter damage due to head injury. Because the brain stem and some other subcortical systems are still functioning, at least partially, the patient has sleep-wake rhythms, and when his eyes are open he may ‘look’ towards or even follow visual or auditory stimuli. This frequently leads relatives to conclude that consciousness is returning; and postural or grasp reflexes in the upper limbs may likewise be mistakenly interpreted as voluntary movements or responses to command. Once witnessed and understood this state is unmistakable; Jennett & Plum (1972) emphasized, when they first described it, that the vegetative state is seldom seen as a stage in the process of recovery to a better ultimate degree of brain functioning. This state is now widely regarded as a worse outcome than death (Jennett, 1976).
Disability in patients who have regained respiration and consciousness Varying degrees of persisting disability occur in patients who sustain permanent brain damage after injury or an episode of hypoxia/ischaemia. This ranges from complete dependence on continuing nursing care, to independence and return to most normal activities. The mental handicap is usually more disabling than the physical, but it may be overlooked or underestimated by casual observers. Improvement, in particular social adaptation to dis-
52
B. JENNETT
ability, may continue over a year or more but serial studies, including psychometric evaluation, indicate that most of the measurable recovery occurs in the first 6 months after brain damage has been sustained; on the four-point outcome scale proposed by Jennett & Bond (1975) it is unusual for the category to change after 6 months.
Conclusions The outcome of resuscitation depends first on whether the cause of the initial event is reversible; and secondly on whether resuscitation was sufficiently speedy to prevent permanent brain damage. Brain death is a readily recognizable entity, and supposed mistakes in the diagnosis of brain death can be attributed either to considering this condition in circumstances which were inappropriate (in the presence of drugs or of hypothermia), or to failure to apply strict criteria, as set out above. In patients in whom spontaneous respiration is restored varying degrees of recovery may occur, ranging from the vegetative state to complete restoration of mental and physical function. A collaborative international study indicates that it may soon be possible to identify criteria by which the ultimate outcome may be reliably predicted in many cases within 24 h of ictus, and in most within 3 days. This should enable those responsible for critical care to reach a decision about how long and at what level to maintain lifesupport measures. Where these are restricted in availability it is important to ensure that they are deployed in the management of patients who are not too badly damaged to benefit from them.
References Caronna, J. J., Leigh, J., Shaw, D., Cartlidge, N., Knill-Jones, R. & Plum, F. (1975) The outcome of medical coma: prediction by bedside assessment of physical signs. Trans. Am. Neurol. Assn. 100, 25-29. Forrester, A. C. (1976) Brain death and the donation of cadaver kidneys. Health Bulletin, 34, 199-204. Jennett, B. (1976) Allocation of resources for the severely brain damaged. Arch. Nezirol. In press. Jennett, B. & Plum, F. (1972) Persistent vegetative state after brain damage. Lancet, i, 734-737. Jennett, B. & Bond, M. (1975) Assessment of outcome after severe brain damage. A practical scale. Lance& i, 480-484. Jennett, B., Teasdale, G., Braakman, R., Minderhoud, J. & Knill-Jones, R. (1976) Predicting outcome in individual patients after severe head injury. Lancet, i, 1031-1034. Walker, A. E. (1976) The neurosurgeon’s responsibility for organ procurement. J. Neurosurg. 44, l-2.
Irrecoverable brain damage after resuscitation: brain death and other syndromes B. JENNETT University Department of Neurosurgery, Institute of Neurological Sciences, Glasgow G5I 4TF. Scotland
Resuscitation procedures are now so widely available in hospital that many patients with cardiac or respiratory arrest are intubated and ventilated as a routine primary measure. By then cardiac function will often be restored and sometimes respiration also. In patients who are still apnoeic but with good heart action, and in whom primary respiratory arrest is presumed, the problem is to discover whether the cause for this is reversible - such as depressant or relaxant drugs, or compression of the brain stem by an intracranial mass that can be removed. If spontaneous breathing returns then resuscitation has proved lifesaving, although the patient may have suffered some degree of irrecoverable brain damage. Should the patient remain apnoeic after the cause of the initial crisis has been investigated and treated then the question of brain death arises. In either event the degree of brain damage should be assessed as soon as possible, so that a decision can be reached about whether life-support measures should be maintained. If primary resuscitation is to become a routine reaction to cardiorespiratory arrest in hospital, then it must become commonplace also to withdraw support once it is obvious that the patient cannot recover. Unless this becomes established as good medical practice there may be increasing reluctance to embark on resuscitative measures. It is sometimes possible to anticipate cardio-respiratory collapse in a patient with an irrecoverable intracranial or extracranial disease process, and to issue prior instructions not to resuscitate. More often the crisis occurs before the nature of the primary disease process has been fully established; those at the bedside, nurses or junior medical staff, have then little option but to resuscitate in order to provide time for a decision to be made as to whether the situation is reversible. There are two reasons why the question of continued support should be considered as soon after resuscitation as possible. One is to avoid deploying the resources of intensive care on patients who are irretrievable for any longer than is necessary. The other is to facilitate organ donation, if this should be appropriate (Forrester, 1976). Brain death This term applies to patients whose respiration has irreversibly ceased owing to irremediable structural brain damage, but in whom the circulation is still adequate because artificial ventilation is being maintained. Had this not been instituted the heart would have stopped soon after the respiratory arrest, from systemic hypoxia. Even if all support is continued there will be progressive dissolution of internal organs in such patients, beginning with the brain; and the heart will continue to beat for only a few days at the most. Before applying criteria for the diagnosis of brain death it is important to ensure that irreversible structural brain damage is in fact the reason for the patient being in coma and apnoeic. The 49
50
B. JENNETT
best evidence for this lies in the clinical history of head injury or of sudden collapse due to intracranial haemorrhage or ischaemia. The latter may be secondary to cardiorespiratory arrest, from heart disease or a complication of anaesthesia or some other hospital procedure. In these cases, and when a patient is found unconscious at home or in the street, the question of drugs causing or contributing to the patient’s state arises. Because drugs may produce reversible suspension of brain activity it is most important to exclude their influence, as far as possible. Toxicological surveys are impractical - the state may result from a combination of several drugs (including alcohol), none of which may be present in toxic doses. The other cause of reversible brain failure is hypothermia, again likely only when patients are found after exposure to low ambient temperatures. BRAIN DAMAGE 1 COMA c IRRECOVERABLE NO BRAIN-&EM
FUNCTION
& RECOVERABLE
4 NO CORTICAL FUNCTION
No respiration
Spontaneousrespiration
No brain-afem reflexes 1 BRAIN DEATH
Some brain-stem reflexes 1 PERSISTENT VEGETATIVE
Heart stops in days
May live weeks, months 01 years
STATE
FULL RECOVERY
Criteria for brain death are best limited to clinical features which can be elicited by doctors in any hospital, and which do not depend either on specialists or on laboratory tests which are not generally available. It is first necessary to confmn that the patient is still apnoeic, by watching for spontaneous respiration during 5 min off the respirator; oxygenation can be satisfactorily maintained by delivering oxygen via a catheter in the endotracheal tube. During this period the Pa,coz should rise to values well above the threshold for stimulating the respiratory centre provided that it is 36 mmHg at the beginning. If there is doubt about this an adequate carbon dioxide level can be assured by ventilating with S% carbon dioxide before disconnection. Brain-stem reflexes should all be absent. The pupils should be fixed to a bright light (size is irrelevant); there should be no facial, corneal or gag responses to stimulation. The oculo-vestibular reflexes should be absent, with no eye movement during or after the slow injection of 20 ml of ice-cold water into each external auditory meatus, clear access to the drum having been established on both sides. Spinal cord function may be preserved for some time after brain death, and reflex movements of the limbs may then persist. Thk laboratory test most often invoked is the EEG, and in various countries EEG societies have stipulated conditions which must be satisfied before a flat or silent record is reported. The high standard of recording required, together with the weight of the decision which depends on it, puts an unfair responsibility on recordists; artifactual activity from various sources, which are difficult to eliminate in the busy intensive care unit, frequently lead to doubt being expressed and a request for a repeat recording next day. The result is that patients who are clearly ‘brain dead’ by clinical criteria may be needlessly maintained on ventilation, to the distress of relatives and staff, and to the detriment of possible organ donation. Because of this, and the restricted availability of EEG facilities, it is increasingly recommended that brain death criteria should be adopted which do not depend on the EEG; this may, however, be used in occasional cases of
CASUALTY
SURGEONS ASSOCIATION
PAPERS
51
unusual difficulty. The other laboratory measures sometimes recommended are even less readily available - cerebral angiography, isotope estimations of blood flow or measures of cerebral arteriovenous oxygen difference. Codes of practice for diagnosing brain death commonly require that criteria be shown to persist for a certain period of time. Earl Walker (1976) has recently pointed out that calling for re-examination over periods of 6-24 h probably represents ‘overkill’and is unduly restrictive. His suggestion is that two examinations 30 min apart, 6 h after the cerebral insult, would seem a practical one for most cases. But there are patients in whom it is clear much sooner than 6 h that no more can be done; unless the question of organ donation arises, which may call for various arrangements to be made, there would then seem no need to delay discontinuation of ventilation.
Apnoea associated with consciousness
Respiratory paralysis and inability to move may result from polyneuritis, poliomyelitis or myasthenia gravis, and such patients may survive for long periods if artificial ventilation is maintained. They are conscious and some or all of the brain-stem reflexes will be present so that confusion with brain death should never occur. More difficult are the rare cases of survival after vascular lesions affecting the ventral pontine region (brain-stem stroke). In these patients the lower brain-stem reflexes are lost but eye movements and eye-lid blinking are preserved, so that some patients learn to communicate by a code which uses this remnant of voluntary movement. This is the state described as the ‘locked-in’ syndrome.
Persistent vegetative state
This describes the patient who is breathing spontaneously, but who remains unresponsive and speechless. No psychologically meaningful response can be elicited because the cerebral cortex is functionally inactive - either because neocortical necrosis has resulted from systemic hypoxia or ischaemia, or because the cortex is disconnected from brain-stem arousal centres by extensive white-matter damage due to head injury. Because the brain stem and some other subcortical systems are still functioning, at least partially, the patient has sleep-wake rhythms, and when his eyes are open he may ‘look’ towards or even follow visual or auditory stimuli. This frequently leads relatives to conclude that consciousness is returning; and postural or grasp reflexes in the upper limbs may likewise be mistakenly interpreted as voluntary movements or responses to command. Once witnessed and understood this state is unmistakable; Jennett & Plum (1972) emphasized, when they first described it, that the vegetative state is seldom seen as a stage in the process of recovery to a better ultimate degree of brain functioning. This state is now widely regarded as a worse outcome than death (Jennett, 1976).
Disability in patients who have regained respiration and consciousness Varying degrees of persisting disability occur in patients who sustain permanent brain damage after injury or an episode of hypoxia/ischaemia. This ranges from complete dependence on continuing nursing care, to independence and return to most normal activities. The mental handicap is usually more disabling than the physical, but it may be overlooked or underestimated by casual observers. Improvement, in particular social adaptation to dis-
52
B. JENNETT
ability, may continue over a year or more but serial studies, including psychometric evaluation, indicate that most of the measurable recovery occurs in the first 6 months after brain damage has been sustained; on the four-point outcome scale proposed by Jennett & Bond (1975) it is unusual for the category to change after 6 months.
Conclusions The outcome of resuscitation depends first on whether the cause of the initial event is reversible; and secondly on whether resuscitation was sufficiently speedy to prevent permanent brain damage. Brain death is a readily recognizable entity, and supposed mistakes in the diagnosis of brain death can be attributed either to considering this condition in circumstances which were inappropriate (in the presence of drugs or of hypothermia), or to failure to apply strict criteria, as set out above. In patients in whom spontaneous respiration is restored varying degrees of recovery may occur, ranging from the vegetative state to complete restoration of mental and physical function. A collaborative international study indicates that it may soon be possible to identify criteria by which the ultimate outcome may be reliably predicted in many cases within 24 h of ictus, and in most within 3 days. This should enable those responsible for critical care to reach a decision about how long and at what level to maintain lifesupport measures. Where these are restricted in availability it is important to ensure that they are deployed in the management of patients who are not too badly damaged to benefit from them.
References Caronna, J. J., Leigh, J., Shaw, D., Cartlidge, N., Knill-Jones, R. & Plum, F. (1975) The outcome of medical coma: prediction by bedside assessment of physical signs. Trans. Am. Neurol. Assn. 100, 25-29. Forrester, A. C. (1976) Brain death and the donation of cadaver kidneys. Health Bulletin, 34, 199-204. Jennett, B. (1976) Allocation of resources for the severely brain damaged. Arch. Nezirol. In press. Jennett, B. & Plum, F. (1972) Persistent vegetative state after brain damage. Lancet, i, 734-737. Jennett, B. & Bond, M. (1975) Assessment of outcome after severe brain damage. A practical scale. Lance& i, 480-484. Jennett, B., Teasdale, G., Braakman, R., Minderhoud, J. & Knill-Jones, R. (1976) Predicting outcome in individual patients after severe head injury. Lancet, i, 1031-1034. Walker, A. E. (1976) The neurosurgeon’s responsibility for organ procurement. J. Neurosurg. 44, l-2.
![[Movements after brain death].](/assets/img/hold.png)
