Ketamine results in a dissociative state, and patients may not be able to speak or respond purposefully to verbal commands. Ketamine can cause vivid imagination, hallucinations, confusion, excitement, irrational behavior, and severe anxiety. Strayer and Nelson have estimated emergence phenomena to occur in between 10% and 20% of adults who have received ketamine. Symptoms can be expected to last 1-3 hours. The incidence of emergence delirium may be reduced by decreasing the recommended dose of ketamine and using it in conjunction with a benzodiazepine. A small hypnotic dose of a short-acting benzodiazepine is recommended to terminate severe emergence reactions. Emergence delirium is not typical in children younger than 15 years.
Ketamine elicits profound dissociative and amnestic actions. In doses typically used for procedural sedation, it does not affect pharyngeal-laryngeal reflexes and thus allows a patent airway as well as spontaneous respiration to maintain intact. This characteristic of the medication is particularly useful for emergency procedures when fasting is not assured. Reflexes may remain intact but cannot be assumed to be protective, however. Cardiovascular and respiratory stimulation and normal or slightly enhanced skeletal muscle tone are observed following administration, although transient respiratory depression may occur if administered too rapidly or in high doses.
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Cite this: Mary L Windle. Fast Five Quiz: Ketamine - Medscape - May 23, 2019.