1. Coma & Brain Death

2. Brain Death
Defined by documentation of irreversible coma and irreversible loss of brainstem reflex responses and f(x) of respiratory centre
OR by the demonstration of the cessation of intracranial flow

3. Brain Death
2 Clinical examinations must be performed by 2 medical practitioners 6 hours apart;
Response to painful stimulation within cranial nerve distribution
Pupillary responses to light
Corneal reflexes
Gag reflex
Cough reflex
Vestibulo-ocular reflexes
Respiratory function
Apnoea test – Preoxygenation with 100% O2 followed by cessation of ventilation
While mechanical ventilation is stopped O2 is supplied through tracheal catheter
AT the end of the period w/o O2 apnoea must persist in the presence of adequate stimulus to spontaneous ventilation PCO2 > 60mmHg and arterial pH < 7.30

4. Brain Death
If this assessment is not possible then radiocontract angiography can be used to look at intracranial blood flow
Flow should be absent in the supratentorial & vertebro-basilar circulation to show brain death
NB: All reversible causes should be ruled out

5. Coma
A state of unconsciousness where patient cannot be wakened or aroused by external stimuli
Occurs from damage to brain regions that control consciousness;
Brainstem reticular activating system above midpons & Both cerebral hemispheres
Defined a;
Not opening eyes
Not obeying commands
Not understanding words

6. Persistent Vegetative State
Coma has progressed to wakefulness without detectable awareness
Usually just need feeds, no ventilation
May open eyes and have sleep cycles

7. Causes of Coma
Diffuse Brain Dysfunction (generalised metabolic toxic injury/widespread inflammation)
Hyperglycaemia (DKA)/Hypoglycaemia
ETOH
Drug intoxication
Hypoxic/IBI
Electrolyte imbalances
Acidosis (resp or metabolic)
SAH
Encephalitis
Cerebral Malaria
Endocrine (hypothroidism/hypoadrenalism)

8. Causes of Coma Direct Effect within Brain Stem
Trauma
Brainstem haemorrhage/infarction
Neoplasm
Pressure effect of the Brain Stem
Hemisphere tumour or abscess
Cerebellar mass lesion
Trauma (SDH/EDH)
Encephalitis

9. Assessment Signs of Trauma Swelling of soft tissues
Racoon eyes – periorbital eccymoses
Blood behind the tympanic membrane (haemotypanum)
Battle’s sign – discoloured swelling over the mastoid bone behind the ear
CSF Rhinorrhoea/Otorrho

10. Assessment Vital Signs BP Temp Respiration
HT may indicate intracerebral haemorrhage or stroke
May also give clue to the cause of the coma (SAH?)
Temp
Hypothermia – ETOH, sedatives, hypoglycaemia
Hyperthermia – heat stroke, infection, hypothalamic lesions
Respiration
Cheyne- Stokes (periodic respiration with hyperpnoea & apnoea due to delay in medullary chemoreceptor response – LVF, brain damage, altitude)
Kussmaul (acidotic) – deep sighing hyperventilation due to stimulation of inspiratory centres – DKA, uraemia, metabolic acidosis
Ataxic – shallow, halting irregular respiration in response to medullary respiratory centre damage

11. Assessment Pupils Normal Pin-point
3-4mm in diameter, equal bilaterally
Constrict briskly+ symmetrically to light
Metabolic acidosis & CNS depressant drugs (not opiates)
Pin-point
1-1.5mm in diameter
Opioid overdose
Pontine lesions, organophosphate poisoning

12. Anisocoria (Assymetrical)
Pupils
Fixed Dilated
7mm or more and fixed (not reactive to light
Results from compression of CN III
Common in herniation of the medial temporal lobe
Fixed Mid-size
5mm in diameter & fixed
Commonly from brainstem lesion at midbrain level
Anisocoria (Assymetrical)
Less than 1mm difference in normal people (20% cases)
Pupil that has reduced constriction – lesion affecting midbrain or CNIII

13. Assessment Optic Fundi
Papilloedema/retinal haemorrhages – HT or raised ICP
Subhyaloid (superficial retinal) haemorrhages – SAH
Ocular Movements
Ocular Axes
Usually slightly divergent in coma
Slow, roving, side to side eye movements in light coma
Doll’s Eye Reflex (Vestibulo-ocular reflex)
Passive head turning produces ocular deviation away from the direction of head rotation
Lost in very deep coma and brainstem lesions
Calorics Testings
Ice water is irrigated into the tympanic membrane
Slow tonic ocular deviation towards irrigated ear (intact brainstem)
Commonly used to Dx brainstem death

14. GCS Eye Opening None To Pain To speech/verbal command Spontaneous 1 23 4
Verbal Response
-None
Incomprehensible sound
Inappropriate words
Confused/disoriented
Talking & orientated 5
Motor Response
Extension
Flexion
Withdrawal
Localised pain
Obeys commands 6

15. CGS 8 is the critical score 90% less than 8 – coma
After 6 hours at 8 50% death rate

16. Investigations FBE Biochemistry – U&E’s, Glucose, Ca, LFt’s
Drugs screen – salicylates, benzodiazepines, narcotics, amphetamines
TFT’s
Blood cultures
CT or MRI – mass leson or intracranial haemorrhage
CSF
EEG – metabolic coma, encephalitis, brain death

17. Management (ED) DRABC IV catheter and Bloods IV infusion (routine)
Thiamine 100mg + dextrose 25g
Thiamine always precedes dextrose as dextrose along can worsen Wernicke’s encephalophaty
Naloxone mg (routine)

18. Management (LT) Fluids & Feeding (NGT or paraenteral)
Skin Care (Pressure sores)
Oral Hygiene (mouth washes + suction)
Eye care – tape eye lids
Physiotherapy – muscles + joints
TED stockingss/heparin – DVT risk
Sphincter Control – Catherisation, rectal evacuation
Family Wishes
References: Acknowledgment J Koh & D Cheng

19. Case Mr GF, 75 y/o retired cook Wife found him slumped over table
Unable to speak, but could undertand
Right side of face drooping, weak right arm
Presented to ED 2 hours later
O/E: unable to speak, obeys simple commands
Right facial droop (pronounced in lower part of face)
Vision & Visual fields intact
Power reduced in right arm, only weak elevation of shoulder and shoulder adduction
Mild weakness of right hip flexion
Soft bruit on auscultation of left carotid artery
BP 165/100

20. PHx:
HT (on ACE inhibitors)
Ex-smoker (40 pack/years)
Quit 10 years ago
FHx
Father, also smoker, died of stroke at 65
Tests:
Haem/biochemical screens normal
Coag screen normal
CT brain reported as normal
MRI: shows area of diffuse restriction in anterior portion of left middle cerebral artery
Repeated CT scan done 48 hours later shows area of low attenuation in same region

21. Speech therapy shows dysphagia w/ uncoordinated swallowing
Made ‘nil by mouth’ + nasogastric tube
Given aspirin
Physio commenced next day
Becomes febrile
Right lower lobe consolidation detected clinically, seen on CXR
Antibiotic & chest physiotherapy
Over next week, return of speech & right arm weakness improves
Carotid doppler shows 80-90% occlusion left carotid
Vascular surgery consulted
Left carotid endarterectomy planned in 6 weeks