MAOI (Monoamine Oxidase Inhibitors) Therapy
Background
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Inhibit breakdown of norepinephrine & serotonin, & also inhibit hepatic microsomal enzymes. These may result in:
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Risk of hypertensive crisis with norepinephrine release
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CNS 'type I' reaction: risk of serotonin syndrome under certain conditions resulting in agitation, headache, fever, seizures, coma, & death
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CNS 'type II' reaction: ↓ hepatic opioid metabolism & thus opioid build-up causing sedation, respiratory depression, & cardiovascular collapse
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Considerations
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Indication for MAOIs: depression, anxiety, psychosis, hypotension, narcolepsy, headache
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Continuation vs discontinuation of MAOI pre-op:
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May need to consult prescribing physician (psychiatry, neurology)
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If possible, try to discontinue 2 weeks pre-op with a tapering regimen
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If cannot discontinue: be mindful of systemic effects below & avoid inpatient diets containing high amounts of tyramine
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Risk of severe hypertension if sympathetic stimulation or sympathomimetic drugs:
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Avoid light anesthesia
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Avoid ketamine, pancuronium
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Avoid indirect acting vasopressors such as ephedrine
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Avoid foods contaning high amounts of tyramine (cheese, wine)
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Risk of CNS adverse reactions:
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Type I reaction leading to serotonin syndrome: avoid anticholinergics & meperidine
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Type II reaction from accumulation of opioids: need to monitor closely for adverse events, opioid use not necessarily contraindicated & have been safely used
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Altered response to anesthetic agents:
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↑ MAC due to ↑ concentrations of CNS norepinephrine
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Possible prolonged succinylcholine effect
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Exaggerated hypotension with neuraxial techniques
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Direct acting vasopressors only, consider ↓ doses
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