Coma, Emergency Medicine

Basics

Description

Light coma:
- Responds to noxious stimuli
Deep coma:
- Does not respond to pain
Unresponsiveness:
- Loss of either arousability or cognition:
  - Loss of arousal
  - Arousal is primarily a brainstem function.
  - Impairment of the reticular activating system
  - Loss of cognition
  - Requires dysfunction of both cerebral hemispheres
- Stupor:
  - Deep sleep, although not unconsciousness
  - Exhibits little or no spontaneous activity
  - Awaken with stimuli
  - Little motor or verbal activity once aroused
Obtundation:
- Mental blunting with mild or moderate reduction in alertness
Delirium:
- Floridly abnormal mental status
- Irritability
- Motor restlessness
- Transient hallucinations
- Disorientation
- Delusions
Clouding of consciousness:
- Disturbance of consciousness
- Impaired capacity to think clearly or perceive, respond to, and remember current stimuli

Etiology

Diffuse brain dysfunction (69%):
- Lack of nutrients:
  - Hypoglycemia
  - Hypoxia
- Poisoning:
  - Ethanol
  - Isopropyl alcohol
  - Ethylene glycol
  - Methanol
  - Salicylates
  - Sedative-hypnotics
  - Narcotics
  - Anticonvulsants
  - Isoniazid
  - Heavy metals
  - Opiates
  - Benzodiazepines
  - Anticholinergics
  - Lithium
  - Phencyclidine
  - Cyanide
  - Carbon monoxide
  - Isoniazid
- Infection:
  - Bacterial/tuberculous/syphilitic meningitis
  - Encephalitis
  - Falciparum meningitis
  - Typhoid fever
  - Rabies
- Endocrine disorders:
  - Myxedema coma
  - Thyrotoxicosis
  - Addison disease
  - Cushing disease
  - Pheochromocytoma
- Metabolic disorders:
  - Hepatic encephalopathy
  - Uremia
  - Porphyria
  - Wernicke encephalopathy
  - Aminoacidemia
  - Reye syndrome
  - Hypercapnia
- Electrolyte disorders:
  - Hypernatremia, hyponatremia
  - Hypercalcemia, hypocalcemia
  - Hypermagnesemia, hypomagnesemia
  - Hypophosphatemia
  - Acidosis, alkalosis
- Temperature regulation:
  - Hypothermia
  - Heat stroke
  - Neuroleptic malignant syndrome
  - Malignant hyperthermia
- Uremia
- Postictal state, status epilepticus
- Psychiatric
- Shock
- Fat embolism
- Hypertensive encephalopathy
Supratentorial lesions (19%):
- Hemorrhage (15%):
  - Intraparenchymal hemorrhage
  - Epidural hematoma
  - Subdural hematoma
  - Subarachnoid hemorrhage
- Infarction (2%):
  - Thrombotic arterial occlusion
  - Embolic arterial occlusion
  - Venous occlusion
- Tumor or abscess (2%):
  - Hydrocephalus
  - Herniation
  - Hemorrhage from erosion into adjacent blood vessels
Subtentorial lesions (12%):
- Infarction
- Hemorrhage
- Tumor
- Basilar migraine
- Brainstem demyelination

Eclampsia

Diagnosis

Signs and Symptoms

History
Ongoing disturbance of consciousness
Physical Exam

No spontaneous eye opening
Lack of response to painful stimuli
No motor activity
Regular cardiorespiratory function
Glasgow Coma Scale (GCS) scoring:
- Eye opening (E):
  - Spontaneously: 4
  - To verbal command: 3
  - To pain: 2
  - No response: 1
- Best motor response (M) to verbal command:
  - Obeys: 6
- Best motor response to painful stimulus:
  - Localizes to pain: 5
  - Withdraws to pain: 4
  - Flexion-abnormal: 3
  - Extension-abnormal: 2
  - No response: 1
- Best verbal response (V):
  - Oriented and converses: 5
  - Disoriented and converses: 4
  - Verbalizes: 3
  - Vocalizes: 2
  - No response: 1
- GCS = E + M + V
Hypothermia:
- Infection, hypoglycemia, myxedema coma, alcohol and sedative-hypnotic poisoning
Fever:
- Infection, thyrotoxicosis, anticholinergics, sympathomimetics, neuroleptic malignant syndrome, hypothalamic hemorrhage
HTN
Structural lesion, hypertensive encephalopathy
Hypotension
Mydriasis:
- Organophosphates
Miosis:
- Narcotics
- Anticholinergics
- Pontine lesion
Loss of pupillary reflexes or unequal pupils:
- Structural lesions
Evidence of head trauma
Nuchal rigidity:
- Meningitis
- Subarachnoid hemorrhage
Decorticate posturing:
- Flexion of elbows and wrists
- Adduction and internal rotation of shoulders
- Supination of the forearms
- Suggests severe damage above the midbrain
Decerebrate posturing:
- Extension of elbows and wrists
- Adduction and internal rotation of shoulders
- Pronation of the forearms
- Suggests damage at the midbrain or diencephalon
Asymmetric movements:
- Structural lesions
- Persistent twitching of an extremity:
  - Status epilepticus

Essential Workup

Detect and treat reversible causes.
Immediate exclusion of comalike states:
- Noting resistance to passive opening of eyelids, fluttering of eyelids when stroked, abrupt eyelid closure, eye movements by saccadic jerks (rather than roving), or finding the eyes rolled back
- Provocation of nystagmus with ice-water caloric testing
- Before paralyzing a patient for intubation, an attempt should be made to detect a locked-in syndrome.
- Demonstrating that the patient is able to blink on verbal command will establish this diagnosis.
- Intubation is still indicated to prevent aspiration.

Diagnosis Tests & Interpretation

Lab

Dextrostix
CBC
Electrolytes
Blood and urine toxicologic screen

Imaging
Head CT:

Diagnosis of hemorrhage and midline shift
CT angiography for suspected cerebrovascular accident

Diagnostic Procedures/Surgery

Lumbar puncture:
- All patients with coma of unknown etiology, particularly if fever is present
- Antibiotics may be administered for as long as 48 hr before lumbar puncture.
- CT should be performed before lumbar puncture if there is evidence of increased intracranial pressure, a mass lesion, pre-existing trauma, or focal findings.
Risk of tonsillar herniation in patients with a mass lesion is very small.
EEG:
- Performed to rule out suspected seizure activities
- Little use in the emergency evaluation
- Unlike EEG studies performed in a lab, lighting will cause artifacts.

Differential Diagnosis

Locked-in syndrome
Psychogenic unresponsiveness
Stupor
Catatonia
Akinetic mutism

Treatment

Pre-Hospital

Airway management if loss of airway patency
Endotracheal intubation if no response to coma cocktail
IV access
Dextrose or Dextrostix
Narcan
Monitor
Look for signs of an underlying cause:
- Medical alert bracelets
- GCS
- Pupils
- Extremity movements

Initial Stabilization/Therapy

Airway management
Empiric use of naloxone
Empiric dextrose:
- Administer if serum glucose cannot be measured at the bedside
- Can safely be administered before thiamine
- Does not worsen outcome in patients with stroke

Ed Treatment/Procedures

Specific therapy directed at underlying cause once identified
Consider empiric use of antibiotics for coma of undetermined etiology:
- Broad-spectrum with good cerebrospinal fluid penetration such as ceftriaxone
Stop seizure activity with benzodiazepines, phenytoin, and phenobarbital.
Empiric treatment for a toxic ingestion:
- Activated charcoal
Correct body temperature:
- Aggressive rewarming for patients with core temperature between 32 °C and 35 °C and invasive rewarming for <32 °C
- Ice packs and forced air movement over exposed wetted skin if severe hyperthermia

Medication

Ceftriaxone: 100 mg/kg IV
Dextrose: 1-2 mL/kg of D50W IV; neonate 10 mL/kg D10W IV; peds 4 mL/kg D25W IV
Diazepam: 0.1-0.3 mg/kg slow IV (max. 10 mg/dose) q10-15min — 3 doses
Flumazenil: 0.20 mg IV qmin — 1-5 doses
Fomepizole: 15 mg/kg IV
Lorazepam: 0.05-0.1 mg/kg IV (max. 4 mg/dose q10-15min)
Mannitol: 0.25-1 g/kg IV over 20 min
Naloxone: 0.01 mg/kg to 0.01-0.1 mg/kg
Phenobarbital: 10-20 mg/kg IV, monitor for respiratory depression
Phenytoin: Infuse at <50 mg/min; 18-20 mg/kg IV/IO or fosphenytoin 15-20 mg/kg IV/IO
Physostigmine: 0.5-2 mg IV
Thiamine: 100 mg IM or 100 mg thiamine in 1,000 mL of IV fluid wide open
Pyridoxine: 70 mg/kg IV (Max. 5 g on a 1:1 basis with INH overdose)

Follow-Up

Disposition

Admission Criteria
Patients who do not have a readily identifiable and completely reversible cause of coma should be admitted.
Discharge Criteria
Comatose patients with correctable hypoglycemia and opiate toxicity who respond completely to aggressive ED treatment can be discharged.
Issues for Referral
Further delineation or prevention of possible adverse medication reaction

Follow-Up Recommendations

If discharged, urgent PCP F/U is needed.
Consideration of adverse medication reaction
Supervision for 24 hr postdischarge

Pearls and Pitfalls

Rapid medical stabilization
Neuroimaging for structural lesions
Metabolic and toxicologic assessment
Identification of unusual causes of coma
Dischargeable patients require period of ED observation.

Additional Reading

Glauser J. Coma: A systematic approach to patient evaluation and management 2008. Available at http://www.thefreelibrary.com/Coma+A+Systematic+Approach+to+Patient+Evaluation+and+Management.-a0206595218
Plum F, Posner J. The Diagnosis of Stupor and Coma. 4th ed. Philadelphia, PA: FA Davis; 2007.
The Martin A. Samuels neurology review for primary care physicians. Available at http//www.cmeinfo.com/store_temp/The_Martin_A._Samuels_Neurology_Review_for_Primary_Care_Physicians_305.asp
Weiner W, Shulman L. Emergent and Urgent Neurology. 2nd ed. Philadelphia, PA: Lippincott, Williams & Williams; 1999.

Codes

ICD9

780.01 Coma

ICD10

R40.20 Unspecified coma
R40.244 Oth coma, w/o Glasgow coma scale score, or w/part score report
R40.2110 Coma scale, eyes open, never, unspecified time
R40.2120 Coma scale, eyes open, to pain, unspecified time
R40.2112 Coma scale, eyes open, never, EMR
R40.2122 Coma scale, eyes open, to pain, EMR
R40.2132 Coma scale, eyes open, to sound, EMR
R40.2142 Coma scale, eyes open, spontaneous, EMR
R40.2212 Coma scale, best verbal response, none, EMR
R40.2222 Coma scale, best verb, incomprehensible words, EMR
R40.2232 Coma scale, best verbal response, inappropriate words, EMR
R40.2242 Coma scale, best verbal response, confused conversation, EMR
R40.2252 Coma scale, best verbal response, oriented, EMR
R40.2312 Coma scale, best motor response, none, EMR
R40.2322 Coma scale, best motor response, extension, EMR
R40.2332 Coma scale, best motor response, abnormal, EMR
R40.2342 Coma scale, best motor response, flexion withdrawal, EMR
R40.2352 Coma scale, best motor response, localizes pain, EMR
R40.2362 Coma scale, best motor response, obeys commands, EMR
R40.241 Glasgow coma scale score 13-15
R40.242 Glasgow coma scale score 9-12
R40.243 Glasgow coma scale score 3-8
R40.24 Glasgow coma scale, total score

SNOMED

371632003 Coma (disorder)
275945006 On examination - comatose (disorder)
274659008 Semicoma (disorder)
230799003 Post-traumatic coma (disorder)

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