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Approach to the Unconscious Patient in the Emergency Department

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1. Definition and Terminology

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2. Pathophysiology (Why Does Coma Occur?)

1. Structural causes - direct damage to the brainstem reticular activating system (RAS) or bilateral cerebral hemispheres
   • Hemorrhage, infarction, herniation syndromes, tumor, abscess
   • Unilateral hemispheric disease alone should NOT cause coma - both hemispheres or the brainstem must be impaired
2. Metabolic/toxic causes - global brain dysfunction without focal signs
   • Hypoglycemia, hypoxia, uremia, hepatic failure, drug intoxication, sepsis

• Uncal herniation: medial temporal lobe compresses the upper brainstem → ipsilateral pupil dilates and becomes non-reactive → progressive drowsiness then unresponsiveness
• Central herniation: progressive loss of consciousness, loss of brainstem reflexes, decorticate → decerebrate posturing

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3. Initial Resuscitation (ABC + Simultaneous Stabilization)

Acute respiratory and cardiovascular problems must be attended to before neurologic assessment.

Step 1 - AIRWAY

• The tongue of the comatose patient in a supine position must be regarded as a foreign body in the oropharynx (Pye's)
• Jaw thrust / chin lift to open airway
• If protection of the airway is in doubt or coma is likely prolonged → endotracheal intubation (Rapid Sequence Intubation)
• Suction secretions (nasopharyngeal and oral)
• Pass a nasogastric tube to empty the stomach and prevent aspiration
• Spinal precaution: if trauma is suspected, immobilize the cervical spine before any airway maneuver

Step 2 - BREATHING

• Administer supplemental oxygen
• Assess respiratory rate and pattern (see Respiratory Patterns below)
• Maintain normal body temperature

Step 3 - CIRCULATION

• Establish secure IV access (large-bore × 2)
• Measure and correct blood pressure
• Assess pulse, SpO2, ECG monitoring
• Correct volume deficits if present

Step 4 - Empirical "Coma Cocktail"

Thiamine must be given before dextrose - giving glucose first in a thiamine-deficient state (alcoholism, malnutrition) can precipitate Wernicke encephalopathy.

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4. Rapid History (While Resuscitating)

1. Circumstances and speed of onset - Abrupt onset → catastrophic event (stroke, seizure, cardiac arrest); Gradual onset → metabolic cause, subdural hematoma, tumor
2. Antecedent symptoms - headache, fever, confusion, vomiting, dizziness, seizures, focal weakness
3. Medications, drugs, alcohol - toxidrome history
4. Chronic medical illness - liver disease, renal failure, diabetes, cardiac disease, psychiatric history
5. Recent trauma - even mild head trauma must be considered

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5. General Physical Examination

The patient must be completely undressed and the entire body examined front and back (Pye's).

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6. Neurological Examination

A. Level of Arousal - Glasgow Coma Scale (GCS)

• GCS ≤ 8 = coma, intubation generally required
• Maximum = 15 (normal); Minimum = 3 (deep coma)

B. Posturing

C. Brainstem Reflexes - Pupillary Signs

D. Eye Movements

• Conjugate horizontal roving: intact midbrain and pons; often metabolic cause
• Eyes deviated to one side: look toward the hemisphere lesion, away from a brainstem lesion
• Ocular bobbing (brisk down, slow up): bilateral pontine damage (basilar artery thrombosis)
• Oculocephalic reflex (Doll's eyes): established after confirming no cervical injury - move head side to side; eyes should deviate opposite to head movement if brainstem intact
• Caloric testing (Oculovestibular reflex): irrigate ear with cold water → eyes tonically deviate toward irrigated side in coma with intact brainstem; absent response = brainstem lesion

E. Respiratory Patterns

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7. Investigations

• Blood glucose (point of care)
• SpO2, ECG monitoring, temperature

• CBC, CMP (electrolytes, BUN, creatinine, glucose, LFTs)
• Arterial blood gas (ABG)
• Serum lactate
• Coagulation profile (PT, aPTT, INR)
• Thyroid function (TSH)
• Toxicology screen (serum + urine)
• Blood cultures (if infection suspected)
• Serum ammonia
• Calcium, Magnesium, Phosphate
• Cortisol (if Addisonian crisis suspected)

• Non-contrast CT head is the imaging of choice first - identifies hemorrhage, mass lesions, midline shift, hydrocephalus rapidly
• MRI brain - superior for posterior fossa, brainstem lesions, early ischemia, basilar artery thrombosis
• If CT is normal and subarachnoid hemorrhage or meningitis is suspected → Lumbar Puncture (LP)
• If basilar artery thrombosis is suspected with normal CT → MRI with MRA or cerebral angiography

• If seizures not clinically evident and patient remains unresponsive after 30 minutes → rule out non-convulsive status epilepticus (NCSE)

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8. Management of Raised Intracranial Pressure

1. Head elevation at 30 degrees, midline position (aids venous drainage)
2. Endotracheal intubation + controlled hyperventilation to PCO2 of 35 mm Hg (brief, temporizing) - causes cerebral vasoconstriction and lowers ICP within minutes; avoid PCO2 <25 mmHg (reduces cerebral blood flow)
3. Mannitol 1-2 g/kg IV over 10-20 min - osmotic agent reducing brain water; monitor renal function
4. Hypertonic saline (5% or 23.4%) - alternative to mannitol; requires central venous access
5. Dexamethasone 10 mg IV then 4 mg q6h - only for edema around tumor or abscess; NOT for diffuse cerebral edema or malignant infarction
6. Correct coagulopathy before LP or surgery
7. Neurosurgical consultation for ICP monitoring and surgical evacuation of epidural/subdural/intraparenchymal hematoma

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9. Cause-Specific Treatment

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10. Special Considerations

• Trauma: always assume cervical spine injury; use jaw thrust instead of head tilt for airway; RSI with in-line stabilization
• Post-ictal state: patient may remain unresponsive after a convulsion; if not awakening within 30 minutes, consider non-convulsive status epilepticus - get EEG
• Pediatric unconscious patient: consider ingestions, infections, NAI (non-accidental injury/child abuse)
• Transfer: only transfer when vital signs are stable; accompany with trained personnel and complete documentation of vitals, GCS, drugs given (Pye's)

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11. Documentation on Admission

1. Level of consciousness (GCS)
2. Pupil size and reaction
3. Blood pressure
4. Pulse
5. Respiratory rate

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Summary Algorithm

UNCONSCIOUS PATIENT ARRIVES
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    AIRWAY (secure, intubate if GCS ≤8, cervical spine precautions)
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    BREATHING (O2, ventilation, respiratory pattern assessment)
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    CIRCULATION (IV access, fluids, BP/pulse/SpO2/ECG)
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    COMA COCKTAIL (Thiamine → Dextrose → Naloxone ± Flumazenil)
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    RAPID HISTORY (AEIOU-TIPS mnemonic, EMS/family)
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    PHYSICAL EXAM (vitals, trauma signs, skin, fundoscopy)
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    NEURO EXAM (GCS, pupils, eye movements, posturing, brainstem reflexes)
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    INVESTIGATIONS (glucose, bloods, ECG, CT head, LP if indicated)
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    TREAT UNDERLYING CAUSE

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• Harrison's Principles of Internal Medicine 22E (McGraw Hill, 2025) - Chapter on Coma
• Tintinalli's Emergency Medicine: A Comprehensive Study - Chapter 168: Coma
• The Washington Manual of Medical Therapeutics - Coma Management
• Pye's Surgical Handicraft, 22nd Edition - The Unconscious Patient
• Adams and Victor's Principles of Neurology, 12th Edition - Coma
• Plum and Posner's Diagnosis and Treatment of Stupor and Coma