Encephalopathy and Coma

Clinical Approach and Management Important Causes

i. Metabolic encephalopathy/coma: (e.g. Drug-overdose, hypoglycemia, fever. When fever is present often fever can be due to an infection at other sites, which coexists with a metabolic encephalopathy or it may be an infection, which can precipitate a metabolic encephalopathy. For example: UTI precipitating uremia or any infection precipitating hepatic encephalopathy or an infective diarrhea with hyponatremia or any infection precipitating an Addisonian crisis, DKA or producing SIADH.

ii. CNS infections: Encephalitis, meningitis, cerebral malaria, brain abscess (always consider these in febrile patients with encephalopathy or coma).

iii. Cerebrovascular accidents: Intracerebral hemorrhage, subarachnoid hemorrhage, massive cerebral infarction, and hypertensive encephalopathy.

iv. Head injury: History of trauma may not be available sometimes.

v. Tumors.

vi. Postictal coma (patient may be brought in coma and the history of seizures may not be available).

vii. Hydrocephalus due to various causes.

viii. Hypoxic/anoxic brain damage: Prolonged hypotension due to any cause, carbon monoxide poisoning/post cardiorespiratory arrest.

ix. non-organic comas, malingering

Emergency Management and Approach to a Comatose Patient

• Clear secretions and foreign bodies from oral cavity and pharynx (including artificial dentures)
• Put an oropharyngeal airway if tongue is falling back
• If the patient is in a gasping state or impending respiratory arrest, do endotracheal intubation and give assisted ventilation with an ambu bag or ventilator
• Oxygen inhalation, if hypoxia is present (clinically or by ABG)
• Note pulse (rate, rhythm, volume, character and peripheral pulses)
• Check blood pressure, temperature and respiratory rate
• Put an IV cannula, collect blood sample for urea, sugar and electrolytes (if necessary, for other investigations as well)
• Start IV fluid - choice of fluid depends on the suspected diagnosis and hemodynamic status of the patient. e.g. Diabetic ketoacidosis - Normal saline only. Do not use Normal saline in fluid overload states like CHF, acute or chronic glomerulonephritis and pulmonary edema.

All comatose patients require indwelling catheter, Ryle’s' tube feeding and care of skin, bowel, bladder and eyes. Bedsores and exposure keratitis are to be prevented by appropriate measures rather than treated.

Physical Examination of a Comatose Patient

In undiagnosed encephalopathy or coma:

a. Search the patient's pockets and other belongings for clues regarding diabetes/epilepsy/drug abuse/suicidal note.

b. Always do a head to foot examination and system wise.

Vital Signs

Pulse

• Bradycardia - suspect raised ICT, hypothyroidism, hypothermia or heart block with seizure due to Stokes-Adams attacks or IHD and CVA
• Atrial fibrillation: Embolic strokes, thyrotoxic crisis (febrile also)
• Rapid, thread—coma with hypovolemia (DKA/acute gastroenteritis)
• Peripheral pulses: asymmetry or absence suggests CVA by atherosclerosis, embolism or vasculitis
• BP
• Hypertension:

CVA and hypertensive encephalopathy

• Hypotension, Shock—think of coma with hypovolemia due to various causes like: Diabetic ketoacidosis, septicemia, Addisonian crisis or acute tubular necrosis with uremia
• Temperature
• Febrile— CNS infections or febrile disease with metabolic Encephalopathy, e.g. UTI leading to DKA/Uremia/Hepatic coma or even pneumonia with hyponatremia due to SIADH
• Pontine hemorrhage
• Hypothermia— myxedema coma, environmental hypothermia
• Respiration
• Tachypnoea with clear lungs on auscultation
• a. Metabolic acidosis— DKA, Uremic coma, Certain poisonings

b. Central Neurogenic Hyperventilation (CNH) as in CVA/CNS infection/hepatic coma/ICSOL

• Tachypnoea with bilateral creps + rhonchi indicating pulmonary edema

a. Organophosphorus poisoning

b. ARDS due to inhalation of toxic fumes

c. Central neurogenic pulmonary edema

Co-existing cardiac pulmonary edematous to IHD/RHD invariably serious (like stroke/myocardial infarction).