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Dr. Falk discusses what needs to be done when a patient unexpectedly does not “wake up” at the end of a general anesthetic: An unresponsive patient in the recovery suite should be approached as if they have a life threatening condition.  Immediate evaluation and survey should include the basics of resuscitation.  Can the patient maintain an airway? Are they respiring effectively?  Are hemodynamic parameters adequate?  If this initial survey is satisfactory further investigation to determine the cause of unconsciousness should be performed.  Oxygenation should be immediately assessed with a pulse oximeter.  A blood gas should be sent to determine ventilatory adequacy and for a quick determination of metabolic abnormalities (pH, PaCO2, glucose, hyper/hyponatremia, hypo/hypercalcemia).  Other labwork should include a chemistry panel and a CBC.  A thorough neurologic exam should be performed checking basic reflexes (pupil response and size, corneal, cough/gag reflex).  In the absence of protective airway reflexes the patient should be intubated.  If there is no suspicion of metabolic abnormalities or residual anesthetic drug, neurologic imaging and testing should be the next diagnostic step including CT scan and EEG.

A Quick Differential Diagnosis includes:

Hypoxemia

Hypercarbia

Hypotension

Hypoglycemia

Narcotic Excess

Residual Neuromuscular Blocking Drug

Residual Volatile Anesthetic

Residual intravenous sedative drugs (midazolam, propofol, etomidate, ketamine, et al)

Central Cholinergic Syndrome (atropine, scopolamine, etc.)

Stroke
Seizure (non-convulsive status epilepticus)

Hypernatremia

Hyponatremia

Hypophosphatemia

Hypo/Hypercalcemia

Severe Anemia

Scott A Falk, M.D., is Assistant Professor of Anesthesiology and Critical Care, Department of Anesthesiology and Critical Care University of Pennsylvania, Philadelphia.  He is also Medical Director of the Post Anesthesia Care Unit at the Hospital of the University of Pennsylvania