“A state of unrousable unresponsiveness

Risk Factors
  • Diabetes
  • Severe illness/infection
  • Liver, kidney or cardiovascular disease
Aetiology

Predominantly by inhaled toxins, genetic predisposition (a1-antitrypsin deficiency)

Pathophysiology
  • Arousal is maintained by the Ascending Reticular Activating System (ARAS), which is a network of neurones in the pons and midbrain ® damage to this leads to a coma
    • toxic – opioid toxicity
    • infectious – sepsis, meningitis
    • metabolic – electrolytic imbalance
    • structural – stroke, subdural haemorrhage
Clinical Presentation
  • Patient unconscious/altered state, make sure to ask those involved with the patient (friends, family, paramedics, witnesses, etc) what may have happened.
  • Abrupt: stroke, seizure, subarachnoid haemorrhage, cardiac arrest
  • Gradual: tumour, subdural haematoma, infection, metabolic disorder
Investigations
  • Immediate assessment:
    • Check ABCDE
    • Measure blood glucose (in case hypoglycaemic)
    • IV access
    • Attach to a cardiac monitor
    • O2 SATs
    • ECG
  • General examination:
    • Temperature
    • Meningism
    • Survey skin (trauma, spinal injury, rash, jaundice, cyanosis, injection marks)
    • Assess respiratory pattern (Cheyne-Stokes or Kussmaul)
  • Neurological exam:
    • Depth of coma (GCS scale – 15 point scale for eye-opening (1-4)
    • Motor response (1-6), verbal response (1-5), <8 = coma)
    • Brainstem function (pupillary reflexes, corneal reflexes and vestibulo-oclear reflexes: Doll’s eye manoeuvre or Caloric test)
  • CBC, electrolytes, PT, PTT, INR, AST, ALT, urea, creatinine, urinalysis, toxic screen, ABG (acidosis, high CO2)
  • CT scan: stroke
  • Lumbar puncture: meningitis & encephalitis
Management
  • Immediate management:
    • “Coma Cocktail”: 50ml glucose IV (hypoglycaemic)
    • IV naloxone (opioid toxicity)
    • Thiamine (malnourished, alcohol abusers to prevent → Wernicke-Korsakoff syndrome)
    • IV flumazenil (benzodiazepine intoxication only if airway compromised)
  • Long-term:
    • Skincare (pressure sores)
    • Oral hygiene
    • Eyecare
    • Fluids
    • Feeding
    • Sphincters
Coma “Look-alikes”
  • Look out for these – the difference between these and coma is that consciousness is preserved:
    • Lock-in syndrome (damage to bilateral pons)
    • Generalized neuromuscular paralysis (caused by toxins e.g. botulinum)
    • Akinetic mutism (damage to prefrontal cortex)
    • Psychogenic coma

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