Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
Coma, reduced consciousness and brain death testing
Essential points for quick revision.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Escalate
Any unexplained reduction in consciousness is an emergency: protect the airway, support breathing and circulation, check glucose immediately, treat seizures and rapidly reversible causes, assess trauma and obtain senior anaesthetic, emergency, neurological or neurosurgical help. Neurological criteria for death are never assessed until prerequisites and exclusions in the current UK Code of Practice are met by appropriately qualified clinicians.
Synopsis
Stabilise and investigate reduced consciousness systematically, distinguish reversible depression from catastrophic brain injury and understand the tightly governed UK process for diagnosing death using neurological criteria.
Use ABCDE before neurological taxonomy. Hypoxia, hypercapnia, hypotension and hypoglycaemia can cause or worsen brain injury and must be corrected while history and examination proceed.
Record the best eye, verbal and motor responses that make up GCS, not only the total. Note intubation, language, hearing, sedation, paralysis, facial injury and baseline disability that limit components.
Establish exact onset and trajectory from witnesses, ambulance records and digital or medication evidence; ask about trauma, headache, seizure, fever, toxins, diabetes, pregnancy, organ failure and psychiatric risk.
Key red flags
Impending herniation pattern
Falling consciousness with a newly dilated or unreactive pupil, progressive motor asymmetry, abnormal posturing, irregular respiration or Cushing-type physiology raises critical intracranial mass effect and requires immediate airway, neurosurgical and imaging action.
Investigation priorities
01
Immediate glucose, blood gas and ECGFirst step
Identify rapidly reversible hypoglycaemia, ventilatory failure, acid-base disturbance and cardiotoxic or electrolyte effects.
Management branches
Undifferentiated comaResuscitate and diagnose in parallel
A patient is unresponsive or substantially below their documented baseline without an established immediately reversible explanation.
Call for senior and airway help, use cervical-spine precautions when indicated, support oxygenation, ventilation and circulation, check glucose, gain IV access and treat active convulsive seizure.
Obtain collateral history and examine GCS components, pupils, gaze, limbs, breathing, temperature, rash and trauma; send focused blood tests, ECG and toxicology samples without delaying urgent CT.
Key medicines
Intravenous glucose for severe hypoglycaemiaGive 150–200 mL glucose 10% or 75–100 mL glucose 20% intravenously, then recheck promptly and repeat or infuse according to response and local emergency policy.
Naloxone for suspected opioid toxicityTitrate intravenous naloxone in locally approved increments to restore adequate ventilation rather than full alertness; use the current emergency or toxicology protocol and repeat dosing or infusion when long-acting opioids outlast it.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.