Coma + PVS + Brain Death Flashcards
Define Coma [3]
“State of unrousable psychologcial unresponsiveness” [1]
Eyes closed [1] & no perceivable response to external stimulus or inner needs [1]
Consciousness depends on 2 things [4]
Arousal:
Intact Ascending Reticular Activating System [1] to alert/awaken consciousness [1]
Awareness:
Functional Cerebral Cortex [1] to determine the content of your consciouness [1]
What could cause your GCS to fall (alter consciousness) [4]
- Toxic/Metabolic states such as intoxication, hypoxia/hypercapnia, sepsis, hypotension, hypoglycaemia, acidosis
- Seizures
- Damage to Reticular Activating System
- Raised ICP such as tumour, stroke, haematoma, SAH or hydrocephalus
Define a Persistent Vegetative State? [3]
Describe in terms of levels of wakefulness vs awareness [1]
After reduced consciousness (mainly comas) the Brain stem recovers to a considerable extent [1] but no recovery of coritcal function [1]
High wakefulness but very low awareness [1]
Define Locked in Syndrome? [3]
Describe in terms of levels of wakefulness vs awareness [1]
Total Paralysis below III nuclei so: [1]
- Can open and vertically move eyes [1]
- But cant move horizontal [1]
Both high wakefullness and awareness [1]
What causes locked in syndrome? [3]
Brainstem Strokes (e.g. Pontine Arteries)
Brainstem Lesions
Traumatic Brain Injury
Whats involved in resus for a patient with reduced consciousness?
ABCD
(Breathing patterns can indicate a specific condition)
Bloods (Glc, biochem, haematology, ABGs, toxicology)
BP/pulse/temp/IV access
Stabilise neck in case of trauma
Look for evidence of meningitis
Neuro exam of coma? [3]
GCS
Brainstem function
Motor function & reflexes
At what glasgow coma scale score do we call it Coma [1]
GCS 8 or less, specifically:
Eye - 2 or less (pain or none)
Verbal - 2 or less (grunting)
Motor - 4 or less (weak flexion)
How do we assess brainstem function? [6]
Brainstem reflexes:
- Pupill reflexes (2&3)
- Corneal Reflex (5 & 7)
- Spontaneous eye movement (3/4/6)
- Oculovestibular (Caloric Stimulation) (3/4/6/8)
- Resp Pattern (Medullary Centres)
- Oculocephalic (normal nystagmus) (3/4/6/8)
Causes of Coma without focal brainstem or lateralizing cerebral signs or meningism? [6]
- Ischaemia
- Metabolic
- Intoxication
- Epilepsy
- Infection
- Hyper/Hypothermia
How would you investigate someone with coma without focal signs or meningism? [5]
Toxicology Bloods Hepatic/renal function ABGs BP
Causes of Coma - 3 broad categories
Meningism = SAH/meningitis/encephalitis
Focal brainstem or lateralizing signs = Tumour, infarct etc
No focal signs or meningism = Toxic(Alcohol)/metabolic(hypoxia)/systemic
How would you continue to care for a coma patient? [7]
- Maintain their vital functions
- Care for their skin, particularly pressure sores
- Attend to bowel/bladder function
- Control seizures
- Prophylaxis for DVTs or Peptic ulcers
- Prevent Contractures
- Assess for Locked in Syndrome
What results of a head injury could lead to focal neuro signs or epilepsy? [3]
- Diffuse axonal injury
- contusions
- Haematoma (intracerebral, extradural, subdural)
How do you manage a head injury? [5]
- Stabilize the C spine
- ABC
- If in coma (GCS <8) intubate and ventilate
- Treat raised ICP
- CT (may need surgery)
Coma with focal brainstem or lateralising cerebral signs differentials [4]
Cerebral tumor
Cerebral hemorrhage
Cerebral infarction
Cerebral abscess
Coma with focal brainstem or lateralising cerebral signs - investigations [4]
CT or MRI obligatory If not diagnostic then investigate other causes of coma: - Metabolic screens - LP - EEG
Medical causes of coma lasting more than 5h [4]
Drug ingestion eg alcohol
Hypoxia secondary to MI
CVA
Metabolic eg diabetes, hepatic failure, renal failure, sepsis
Factors affecting prognosis of coma [4]
Age
Cause
Depth
Duration
GCS Total score? Lowest score? Score breakdown: Motor? Verbal? Eyes?
Total score 15
Lowest score 3
Motor 6
Verbal 5
Eye 4
GCS
Describe what qualifies for motor scoring
- Obeys commands
- Localises to pain
- Withdraws from pain
- Abnormal flexion to pain (decorticate posture)
- Extending to pain
- None
GCS
Describe what qualifies for verbal scoring
- Orientated
- Confused
- Words
- Sounds
- None
GCS
Describe what qualifies for eye opening scoring
- Spontaneous
- To speech
- To pain
- None
Criteria for brain stem death testing [4]
Deep coma of known aetiology.
Reversible causes excluded
No sedation
Normal electrolytes
Testing for brain death: who [4]
The test should be undertaken by two appropriately experienced doctors on two separate occasions.
Both should be experienced in performing brain stem death testing and have at least 5 years post graduate experience.
One of them must be a consultant.
Neither can be a member of the transplant team (if organ donation contemplated).
Tests for brain death [6]
Pupillary light reflex: fixed, non responsive to light Corneal reflex: none Oculo-vestibular reflexes Supra-orbital pressure: no response Cough or gag reflex: none Respiratory effort
How to determine no oculovestibular reflex?
no eye movements following slow injection of at least 50mL ice cold water into each ear in turn (caloric test)
How to determine no respiratory effort
no observed respiratory effort in response to disconnection of ventilator for long enough (typically 5 min) to ensure PaCO2 >6.0kPa (6.5 in chronic CO2 retention); adequate oxygenation is ensured by pre-oxygenation and diffusion oxygenation during disconnection (so brainstem respiratory centre not challenged by ultimate anoxic drive stimulus)
