A new review in the journal Current Opinion in Anesthesiology examines the use of ketamine in ambulatory anesthesia, particularly its dose-dependent effects on breathing and cortical function.
Noting that low-dose ketamine can be used in ambulatory surgery following an assessment of risks and benefits, the researchers state that ketamine “decreases the firing rate of fast-spiking gamma-aminobutyric acidergic interneurons, leading to a disinhibition of pyramidal neurons and enhanced cortical and respiratory arousal,” which results in an “activation of the sympathetic nerve system and an increased drive to upper airway dilator and respiratory pump muscles.”
They state that low-dose ketamine’s parallel effects on cortical function can be beneficial, particularly “delirium and posttraumatic stress disorder prevention through relief of pain and discomfort, and mood stabilization.” They warn, however, that higher doses of ketamine increase the risk of respiratory complications, including airway secretions, predisposal to laryngospasm, and desaturation.
They add that “when given to anxious patients without concomitant use of benzodiazepines, ketamine increases the risk of frightening and delusional memories.”
They conclude that low-dose (<0.5 mg/kg) intravenous ketamine provides “excellent analgesia, improves breathing and circulation, and stabilizes mood, which can help prevent postoperative delirium”—but that it also “carries the risk of frightening and delusional memories, when given to anxious patients in the absence of concomitant premedications” such as midazolam 0.03 mg/kg.
