Coma, Persistent Vegetative State, Brain Death Flashcards
What does consciousness depend on?
Intact descending reticular activating system to act as the alerting or awakening element of consciousness
Functioning cerebral cortex of both hemispheres which determines the content of the consciousness
Causes of decreased GCS
Toxic metabolic states e.g. hypoxia, hypotension, drug intoxication, renal failure, hypoglycaemia, ketoacidosis
Seizures
Damage to reticular activating system
Causes of raised ICP e.g. tumour, stroke
What is a coma?
State of unrousable psychological unresponsiveness in which the subjects lie with eyes closed and show no psychologically understandable responses to external stimuli or inner need
What is a persistent vegetative state?
State in which the brainstem recovers to a considerable extent but there is no evidence of recovery of cortical function. There is arousal and wakefulness but the patient does not regain awareness or purposeful behaviour of any kind.
What is locked in syndrome?
Where the patient has paralysis below the level of the third nerve nuclei. They can open, elevate and depress the eyes but have no horizontal eye movement and no other voluntary eye movement.
What does the diagnosis of locked in syndrome depend on?
Recognising that the patient can open their eyes voluntarily and signal numerically by eye closure
Important points of history of a patient in a coma
Predictable progression of underlying illness
Unpredictable event in patient with previously known disease
Totally unexpected e.g. head injury, sudden collapse, limb twitching, previous history of drug/alcohol abuse
Important points of examination and monitoring of a patient in a coma
Temperature Heart rate BP Respiration Skin, breath Abdomen Meningism signs Fundal exmaination Neurological assessment using GCS, brainstem function, motor function and reflexes
Glasgow coma scale - eye opening criteria and scoring
Spontaneous - 4
To speech - 3
To pain - 2
None - 1
Glasgow coma scale - best verbal response criteria and scoring
Orientated - 5 Confused - 4 Inappropriate words - 3 Incomprehensible sounds - 2 None - 1
Glasgow coma scale - best motor response criteria and scoring
Obeying commands - 6 Localising to pain - 5 Withdrawing from pain - 4 Flexing to pain - 3 Extending to pain - 2 None - 1
What GCS score indicates coma?
< 8
Cranial nerves tested by pupillary reactions
II and III
Cranial nerves tested by corneal responses
V and VII
Cranial nerves tested by spontaneous eye movements
III, IV, VI
Cranial nerves tested by oculocephalic responses
III, IV, VI, VIII
Cranial nerves tested by oculovestibular responses
III, IV, VI, VIII
Nerves tested by respiratory pattern
Medullary centre
Blood tests done for a patient in a coma
Glucose Biochemistry Haematology Blood gas Toxicology
What needs to be established in a patient in a coma?
Baseline blood pressure, pulse, temperature
IV access
Stabilise neck
Conditions to consider in coma without focal or lateralising signs and without meningism
Anoxic/ischaemic conditions Metabolic disturbances Intoxications Systemic infections Hyperthermia/hypothermia Epilepsy
Investigations to be done for a patient in a coma
Toxicology screen including alcohol level Measure blood sugar and electrolytes Assess hepatic and renal function Acid-base assessment and blood gases Measure BP Consider carbon monoxide poisoning
Conditions to consider in coma without focal or lateralising signs but with meningism and investigations to do
Subarachnoid haemorrhage
Meningitis
Encephalitis
CT head
Lumbar puncture
Conditions to consider in coma with focal brainstem or lateralising cerebral signs and investigations to do
Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abscess
CT/MRI
Metabolic screen, lumbar puncture, EEG
Medical causes of coma lasting > 5 hours
40% drug ingestion +/- alcohol
25% hypoxia
20% cerebrovascular event
15% metabolic
Factors affecting prognosis of patients in a coma
Age Cause Depth of coma Duration of coma Clinical signs, most importantly brainstem reflexes
What percentage of patients in a non-traumatic coma for more than 6 hours will make a good or moderate recovery?
15%
Management of patients in a coma
Resuscitation - ABCs Maintenance of vital functions Care of skin Bladder and bowel function Control of seizures Prophylaxis of DVT and peptic ulceration Prevention of contractures Consider locked-in syndrome
Head injury can lead to focal neurological signs/epilepsy due to
diffuse axonal injury
contusion
intracerebral haematoma
extracerebral haematoma
Management of head injury
Stabilise cervical spine
Airway, breathing and circulation stabilisation
Intubation and ventilation if GCS 8 or less
Treat raised ICP
Cranial imaging
Neuro-observation
Treatment of increased ICP
Surgery to relieve pressure
Osmotic agents
Maintain good PO2, reduce PCO2
Reduce metabolism
