Coma

Coma is defined as a persisting state of deep unconsciousness with sustained GCS of 8 or less. 

Assessment

• Short history from the attendants

Once the patient is stable from a cardiorespiratory perspective, then

• accurate assessment of conscious level 
• thorough general medical examination, 

• looking for clues such as needle tracks indicating drug abuse, rashes, fever 
• focal signs of infection, including neck stiffness or evidence of head injury. 

• Focal neurological signs may suggest 

• structural explanation (stroke or tumor) or 
• may be falsely localizing (for example, 6th nerve palsy can occur as a consequence of raised ICP). 

• Sodium and glucose should be measured urgently as part of the initial assessment, 
• Further investigations should be guided by the clinical presentation and examination findings; 
• A sudden onset suggests a vascular cause. 

• CT with CTA 

• Features suggestive of cerebral venous thrombosis, such as thrombophilia or sinus infection, 

• CT venogram 

• Meningitis or encephalitis may be suggested by the history, signs of infection or subtle radiological findings.

• broad-spectrum antibiotics and antivirals while awaiting more definitive diagnostic information. 

• Other drug, metabolic and hepatic causes. 
• An ammonia level (sent on ice) can narrow the differential diagnosis to a metabolic or hepatic cause if there is diagnostic doubt; Psychiatric conditions such as catatonic depression or neurological conditions such as the autoimmune encephalitides can cause a reduced level of consciousness, but they are diagnoses of exclusion and will require specialist input. 

Management 

• Moving an unconscious patient into the recovery position is best for airway protection while preparations are made for escalation to a higher level of care.