Coma, Persistent Vegetative State, BrainDeath Flashcards
What two factors does consciousness depend upon
An intact ascending reticular activating system
Functional cerebral cortex of both hemispheres
What is the function of the reticular system in consciousness
Arousal -acts as the alerting or awakening element of consciousness
What is the function of the cerebral cortex in consciousness
Awareness of the environment -determine the content go consciousness
What is the affect of the two components of consciousness in a coma
Low level of consciousness (wakefulness) - RAS
Low content of consciousness (awareness) - CH
What is the affect of the two components of consciousness in a vegetive state
Low content of consciousness (awareness)
High level of consciousness (wakefulness)
What are potentially causes of decreased consiousness
Toxic metabolic stress
eg ischaemia, hypoglycaemia, hepatic or renal failure
Seizures
Damage to the reticular activating system
Causes of raised intracranial pressure
What are causes of toxic metabolic stress that results in decreased consciousness
Hypoxia/hypercapnia/sepsis/hypotension
Drug intoxication/renal or liver failure
Hypoglycaemia, ketoacidosis
What are causes of raised intracranial pressure that results in decreased consciousness
tumour, stroke, Extra dural haematoma Sub dural haematoma Subarachnoid haemorrhage hydrocephalus
What pathological affects can result in decreased consciences
Diffuse hemisphere damage
Focal damage
Brainstem involvement
- herniation
- compression (mass)
Define coma
A state of unrousable psychological unresponsiveness in which the subjects lie with eyes closed and show no psychologically understandable response to external stimulus or inner need
What is the pathology of a persistent vegetative state
A state in which the brain stem recovers to a considerable extent but there is no evidence of recovery of cortical function
What is the affect of persistent vegetive state
There is arousal and wakefulness but the patient does not regain awareness or purposeful behaviour of any kind
What is the affect of “locked in” syndrome
able to open, elevate and depress the eyes, nut has no horizontal eye movements and no other voluntary eye movement
What does the diagnosis of locked in syndrome depend upon
recognising that the patient can open their eyes voluntarily and signal numerically by eye closure
Define resuscitation
the action or process of reviving someone from unconsciousness or apparent death
What should first be considered in resuscitation
ABC
Airway
Breathing
Circulation
Why is it important to listen to breathing pattern
can give indication to the problem
What doe depressed respiration potentially indicate
Drug overdose
metabolic disturbance
What does increased respiration potentially indicate
Hypoxia
Hypercapnia
acidosis
What does a fluctuating respiration potentially indicate
Brainstem lesion
What is important to retrieve from unconscious patient to help determine cause of state
Blood sample:
Glucose, biochemistry, haematology, blood gas and toxicology
What is additional steps in resuscitation
Establish base line (BP, pulse, temp)
Find IV access
Stabilise neck
examine evidence for meningitis
Why is it important to gain a history of unconscious patients
if this was a predictable progression of underlying illness
An unpredictable event in previous known disease
A totally unexpected event in the patient
If a totally unexpected event in patient history what additional information do you need to gather
Head injury
sudden collapse
limb twitching
previous history of drug or alcohol abuse
What do you examine and monitor in a unconscious patient
Temperature Heart rate, Blood Pressure, CVS Respiration Skin, breath Abdomen Meningism Fundal examination
What are three version for neurological assessment of coma
Glasgow Coma Scale
Brainstem Function
Motor Function + Reflexes
What is the Glasgow coma scale for eye opening
Spontaneous 4
To speech 3
To pain 2
None 1
What is the Glasgow coma scale for best verbal response
Orientated 5 Confused 4 Inappropriate words 3 Incomprehensible sounds 2 None 1
What is the Glasgow coma scale for best motor response
Obeying Commands 6 Localising to pain 5 Withdrawing from pain 4 Flexing to pain 3 Extending to pain 2 None 1
How does the Glasgow coma scale define if someone is in a coma
“Patients who fail to show eye opening in response to voice, perform no better than weak flexion in response to pain and make, at best, only unrecognisable grunting noises in response to pain are regarded as being in coma”
What is the Glasgow coma scale score of a coma
Eye opening - 2 or less
Verbal response - 2 or less
Motor response - 4 or less
GCS <8 =
How do we access brain stem function
Pupillary reactions
Corneal responses
Spontaneous eye movements
Oculocephalics response (Doll’s eye)
Oculovestibular responses
Respiratory pattern
What cranial nerves does pupillary reaction test in the brain stem
CN II + III
What cranial nerves does corneal response test in the brain stem
CN V + VII
What cranial nerves does spontaneous eye movement test in the brain stem
CN III, IV, VI
What cranial nerves does oculocephalic reflex response test in the brain stem
(tested by holding the eyes open and rotating the head from side to side or up and down)
CN III, IV, VI, VIII
What does respiratory pattern access in the brainstem
Medullary centres
How do you access motor function in an unconscious patient
Motor response
Muscle tone
tendon reflex
seizure evidence
What is the potential cause of coma without focal or lateralising signs and without meningism
Anoxic/ ischaemic conditions
Metabolic disturbances
Intoxications
Systemic infections
Hyperthermia/ Hypothermia
Epilepsy
What is the investigations for a coma without focal or lateralising signs and without meningisml
Toxicology screen
including alcohol level
Measure blood sugar and electrolytes
Assess hepatic and renal function
Acid - base assessment and blood gases
Measure blood pressure
Consider carbon monoxide poisoning
What is the causes of a Coma without focal or lateralising signs but with meningism
Subarachnoid Haemorrhage
Meningitis
Encephalitis
What is investigations for Coma without focal or lateralising signs but with meningism
CT Head scan
Lumbar puncture
What is assessed in the lumbar puncture in a coma with meningism
Appearance of CSF (cloudy)
Cell count
Glucose level
Capsular antigen tests
What is the potentially causes of a coma with focal brainstem or lateraling cerebral signs
Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abscess
Investigations for Coma with focal brainstem or lateralising cerebral signs
CT or MRI obligatory
investigate as for other causes of coma:
- metabolic screens
- lumbar puncture
- EEG
What is the medical cause of comas lasting more than 5 years
Drug ingestion ± alcohol (40%)
Hypoxia e.g. secondary to MI (25%)
Cerebrovascular event, either haemorrhage or infarction (20%)
Metabolic e.g. diabetes, hepatic failure, renal failure, sepsis, hypercapnia/hypoxia (15%)
What factors affect the outcome of a coma
Age
Cause of coma
Depth of coma
Duration of coma
Certain clinical signs, the most important of which are the brain stem reflexes
What is the predicted outcome of a non traumatic coma
15% of patients incoma for more than 6 hours will make a good or moderate recovery
85% will die, remain vegetive or reach a state of severe disability in which they remain dependent
What is the management of patients in a coma
Maintenance of vital functions
Care of skin, avoidance of pressure sores
Attention to bladder and bowel function
Control of seizures
Prophylaxis of DVT, peptic ulceration
Prevention of contractures (hardening of muscle, tendon tissue etc)
What should be considered in coma patients
“locked-in” syndrome
Head injury can lead to focal neurological signs/epilepsy as causes the development of what
Diffuse axonal injury
Contusion (bruise)
Intracerebral haematoma
Extra-cerebral haematoma
- Extra-dural haematoma
- Sub-dural haematoma
How do you diagnose a head injury
CT scan
What is the management of a head injury
Stabilise cervical spine
Airway/Breathing/Circulation
If GCS≤8 - intubation+ventilation
Treat raised ICP
Cranial imaging - may need decompressive surgery or removal of haematoma
Neuro observation
What is 6 different ways in treating and manage increased intracranial pressure
Surgery to relieve pressure (heamatoma, ventricular shunt)
Osmotic agents e.g. mannitol
Nurse with head at 30-45% (Venous return)
Reduce pain
Maintain good PO2, reduce PCO2
Reduce metabolism (reduce temperature, barbiturates)