Delayed emergence: differential diagnosis


Differential diagnosis of delayed emergence can be classified into one of three causes: drug effects, metabolic disorders, or neurologic disorders. If a patient doesn’t “wake” after an anesthetic you have to go down these three in that particular order.

Delayed Emergence Rapid Panel

  • Vital signs (including temperature)
  • Twitch monitor
  • Neurologic Exam (pupils, cranial nerves, reflexes, response to pain)
  • Fingerstick glucose
  • ABG with electrolytes
  • Make arrangements for naloxone, flumazenil, physostigmine, imaging (ex. CT scan)

Drug Effects

Included under drug effects are:

  1. Residual anesthetic (volatile, propofol, barbiturates, ketamine)
  2. Excess narcotics – can be reversed by naloxone (40 ucg boluses) – remember it’s short-acting
  3. Preoperative sedatives – too much midazolam? – reversed by flumazenil 0.2 mg q1min up to 1 mg
  4. Physostigmine 1.25 mg IV can reverse cholinergic effects (ex. scopolamine) and possibly the effects of anesthetic agents (Stanford Delayed Emergence Protocol)
  5. Inadequate reversal or no reversal of muscle relaxation or rarely pseudocholinesterase deficiency – edrophonium/atropine work faster (1-2 mins) than neostigmine/glycopyrrolate (peak effect around 10 mins) and may be indicated in this setting
  6. Acute alcohol intoxication or other illicit drugs rendering unconsciousness extending the length of the anesthetic

Emergence Protocol

Metabolic Disorders

Included under metabolic disorders are:

  1. Hypercarbia – check a gas, may need to ventilate postoperatively until the patient resumes adequate spontaneous ventilation
  2. Hypoxemia – may require mechanical ventilation or supplemental oxygen
  3. Acidosis – correct the underlying disorder (metabolic/respiratory)
  4. Hypoglycemia/Hyperglycemia – check a gas, correct as indicated
  5. Hyponatremia – correct slowly such as not to create central pontine myelinolysis
  6. Hypothermia/Hyperthermia – correct as indicated
  7. Underlying metabolic disorder – e.g. liver disease

Neurologic Disorders

Included under neurologic disorders are:

  1. New ischemic event
  2. Cerebral Hemorrhage
  3. Seizures or post-ictal state
  4. Increased ICP or pre-existing obtundation

Remember if the patient is unable to protect airway reflexes then it is best to maintain a secure airway (keep them intubated) until the patient is awake and able to protect their airway.

Similar keyword: Delayed emergence: DDx


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