Coma, Persistent Vegitative State, Brain Death Flashcards
Define coma
A state of unrousable physiological unresponsiveness (in which the subjects lie with eyes closed and show no physiologically understandable response to external stimulus or internal need)`
What are the two functions that consciousness relies on?
AROUSAL
An intact ascending reticular activating system - to act as the alerting or awakening element of consciousness
AWARENESS OF ENVIRONMENT
A functioning cerebral cortex of both hemispheres - which determines the content of the consciousness
What are some causes of a decreased GCS?
Toxic/metabolic states
- hypoxia/hypercapnia/sepsis/hypotension
- drug intoxication/renal or liver failure
- hypoglycaemia, ketoacidosis
Seizures
Damage to reticular activating system
Causes of raised ICP
- tumour, stroke, EDH, SDH, SAH, hydrocephalus
Describe 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
There is arousal and wakefulness but the patient does not regain awareness or purposeful behaviour of any kind
What is ‘locked-in syndrome’?
The patient has total paralysis below the level of the third nerve nuclei and, although able to open, elevate and depress the eyes, has no horizontal eye movement and no other voluntary eye movements
What is the diagnosis of locked-in syndrome dependant upon?
The ability of the patient to open their eyes voluntarily and signal numerically by eye closure
Outline resuscitation in a comatose patient
Airway
Breathing
- Depressed respiration = drug overdose, metabolic disturbance
- Increased respiration = hypoxia, hypercapnia, acidosis
- Fluctuating respiration = brainstem lesion
Circulation
Blood Samples
Establish baseline BP, pulse, temperature, IV access and stabilise neck
Examine for meningitis - TREAT ON SUSPICION
What should be considered when obtaining a history pertaining to a comatose patient?
Predictable progression of underlying illness?
Unpredictable event in patient with previously unknown disease?
Totally unexpected event? - head injury, collapse, twitching? Previous history or drug or alcohol abuse?
What should be examined (and monitored) in a comatose patient?
Temperature HR, BP, CVS Respiration Skin, breath Abdo Meningism Fundal exam
What neurological assessments can be made to asses coma?
GCS
Brainstem function
Motor function and refelxes
What GCS score is considered to classify the patient as comatose?
=/
What nerves control pupillary reactions?
III, IV
What nerves control corneal responses?
V, VII
What nerves control spontaneous eye movement?
III, IV, VI
What nerves control oculocephalic responses?
III, IV, VI, VIII
What nerves control oculovestibular responses?
III, IV, VI, VIII
What controls the respiratory pattern?
Medullary centre
What four things indicate the motor function?
Motor response
Motor tone
Tendon reflexes
Seizures
If there are focal brainstem or lateralising cerebral signs in coma what may this indicate?
Meningism
BUT - Meningism may still present with no lateralising signs
What are some causes of coma without lateralising signs i.e. without Meningism?
Anoxic/ischaemic conditions Metabolic disturbances Intoxications Systemic infections Hyperthermia/Hypothermia Epilepsy
What are the Ix for coma without lateralising signs or Meningism?
Toxicology screen including alcohol level Blood sugar and U&Es RFTs LFTs Acid tests BP CO poisoning?
What are some causes of coma without lateralising signs but with Meningism?
SAH
Meningitis
Encephalitis
What are the Ix for coma without lateralising signs but with Meningism?
CT head
LP - if CT is normal
What are some causes for coma with lateralising signs and Meningism?
Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abscess
What are the Ix for coma with lateralising signs and Meningism?
CT or MRI - OBLIGATORY
If not diagnostic, use metabolic screens, LP, EEG to look for other causes of coma
Folow through the table of causes for coma with and without lateralising signs, amd with and without meningism
Lateralising sings NO, Meningism NO = Toxic/Metabolic/Systemic
Lateralising signs NO, Meningism Yes = SAH/Meningitis/Encephalitis
Lateralising signs YES, Meningism YES = Focal cerebral e.g. tumour, infarct
Outline the major medical causes of coma lasting for more than 5 hours
40% due to alcohol or drugs
25% due to hypoxia e.g. secondary to MI
20% due to cerebrovascular event, either haemorrhage or infarction
15% metabolic e.g. diabetes, hepatic failure, renal failure, sepsis, hypercapnia/hypoxia
What factors influence the outcome of coma?
Age Cause Depth Length Clinical signs, most importantly the brainstem reflexes
What proportion of patients in a non-traumatic coma for more than 6 hours will make a moderate or good recovery?
15%
What are the foundations of continuing care of coma patients?
Maintenance of vital functions Care of skin, avoidance of pressure sores Attention to bladder and bowel function Control of seizures Prophylaxis of DVT/PE, peptic ulceration Prevention of contractures Consider locked-in syndrome
What brain insults that are caused by head injury can lead to neurological signs/epilepsy?
DAI Contusion Intracerebral haematoma Extra-cerebral haematoma -Extra-dural haematoma -Sub-dural haematoma
How does a subdural haematoma appear on CT?
Convex ellipse
How does an extradural haematoma appear on CT?
Concave lens
What os the management for head injury?
Stabilise c-spine
CABC
If GCS =/
How is raised ICP treated?
Surgery to relieve pressure Osmotic agents e.g. mannitol Nurse with head at 30-45% Reduce pain Maintain good PO2, reduce PCO2 Reduce metabolism, reduce temperature with barbiturates
