A 74-year-old man is evaluated for acute agitation beginning 20 minutes after arrival to the post-anesthesia care unit (PACU) following abdominal surgery. He was admitted 5 days ago for a small bowel obstruction and failed nonoperative management. The patient received lorazepam for preoperative anxiety, and lysis of adhesions was performed under general anesthesia. His immediate postoperative course was uneventful, and he was responsive and following commands shortly after extubation and on arrival to the PACU. Medical history is significant for posttraumatic stress disorder. Temperature is 37.2 C (99 F), blood pressure is 142/86 mm Hg, pulse is 98/min, and respirations are 18/min. The patient is anxious, confused, and restless in bed. He now responds only to questions in Spanish despite being fluent in English minutes before. His muscles seem tense, but screening neurologic examination reveals no focal abnormalities. Arterial blood gas shows PaO2 of 86 mm Hg and PaCO2 of 38 mm Hg. Point-of-care electrolytes, glucose, and hematocrit are all normal. What is the most appropriate initial management of this patient?
Emergence from anesthesia | |
Normal emergence |
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Inadequate emergence |
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OR = operating room. | |
Emergence is the transition from general anesthesia to consciousness; most patients are fully awake within 15 minutes. Inadequate emergence (ie, failure to achieve alertness after anesthetic cessation) has 2 subtypes:
Delayed emergence: A hypoactive state that includes somnolence persisting >30-60 minutes.
Emergence delirium: A hyperactive state (eg, agitation, disinhibition) that usually manifests in the operating room but sometimes develops after initial normal emergence (eg, within 45 minutes). It is common in children; in adults, it is more frequent after abdominal/breast surgery and in patients with a psychiatric history (eg, posttraumatic stress disorder).
This patient's acute-onset confusion, cognitive dysfunction (eg, lost language fluency), and agitation shortly following normal emergence from surgery is consistent with emergence delirium. Both delayed emergence and emergence delirium are commonly due to residual effects of anesthetic/adjuvant medications (eg, inhaled anesthetics, neuromuscular blockers, benzodiazepines). In most patients, these conditions are temporary and resolve with drug metabolism. Therefore, initial management consists of reassurance and reorientation.
Rarely, delayed emergence/emergence delirium may signal a serious underlying condition (eg, hypercapnia, acute stroke). Therefore, urgent evaluation includes focused (eg, neurologic) examination and laboratory assessment (eg, arterial blood gas). If focal neurologic findings are present, emergency head CT is indicated; however, acute neurologic events are rare causes of delayed emergence/emergence delirium, typically occuring after certain procedures (eg, carotid endarterectomy) (Choice D). Common postoperative conditions (eg, acute pain) that prolong delirium should be considered.
(Choice A) Dantrolene is used to treat malignant hyperthermia (MH) induced by inhaled anesthetics (eg, halothane). Although agitation causes muscle tension, MH would demonstrate true muscle rigidity (ie, sustained contraction), and hypercapnia (being the most reliable indicator) would be expected; hyperthermia often occurs later.
(Choice B) Benzodiazepines frequently prolong (rather than treat) delirium and should be avoided if possible. Benzodiazepines (eg, lorazepam) are useful for delirium due to withdrawal syndromes (eg, alcohol, sedative-hypnotic) or when antipsychotics fail in severely agitated patients.
(Choice C) Physical restraints can increase agitation and prolong delirium. They are a last resort and should be used only when other measures fail with persistent patient danger.
Educational objective:
Inadequate emergence from general anesthesia (ie, delayed emergence, emergence delirium) is typically due to residual effects of anesthetic/adjuvant medication. It is usually temporary and resolves with reassurance and reorientation, although urgent evaluation to exclude more serious conditions should be considered.