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Abnormal secretion of vasoactive substances (i.e., histamine, kallikrein, serotonin) by carcinoid tumor.
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Most common localization of tumor: small bowel, stomach, and ovaries.
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- Measurement of 5-hydroxyindoleacetic acid (5HIAA) is most commonly used to diagnose carcinoid
- Echocardiogram may help delineate the level of cardiac involvement (pulmonic stenosis and TR most common)
- If diarrhea, possible hypokalemia
- Octreotide 100 mcg SQ tid in the preceding 2 weeks; increase dose if needed until symptoms disappear, up to 500 mcg tid
- Monitor LFTs and blood glucose
- Patients on octreotide should continue their dose on the morning of surgery
- Anoxiolysis with benzodiazepines should be given to prevent stress-induced release of serotonin
- H1 and H2 blockers should also be given (e.g., diphenhydramine 25 mg IV and ranitidine 50 mg IV)
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Monitors: A-line is useful because manipulation of the tumor can cause wide hemodynamic fluctuations.
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CVL and PAC may also be helpful; consider TEE if altered cardiac function.
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Induction: Etomidate or propofol can be used as long as hemodynamic stability is maintained. Succinylcholine should be avoided because of possible histamine release.
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Intraoperative: All inhalation agents acceptable but desflurane may be preferable because of low hepatic metabolism in cases of liver metastasis of tumor.
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Measure electrolytes frequently.
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Volume expansion may be helpful with crystalloid or colloid.
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Avoid drugs known to provoke release of mediators.
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Octreotide 25–100 mcg should be used prior to tumor manipulation to attenuate hemodynamic effects.
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Hypotension should be treated with volume expansion and octreotide and not with catecholamines/sympathomimetics.
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Hypertension: deepen anesthesia, then IV esmolol.
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ICU with invasive hemodynamic monitoring for 48–72 hours.
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Taper octreotide over 3–4 days.
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Pain control necessary to prevent stress-induced release of mediators; avoid morphine.
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Carcinoid crisis can be precipitated by stress, tumor necrosis, or surgical stimulation, as well as from anesthetic drugs such as succinylcholine.
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Octreotide infusion at 50–100 mcg/h can be given with boluses of 25–100 mcg for treatment of crisis.
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Octreotide is a synthetic, long-acting analog of somatostatin, a naturally occurring hormone produced by δ cells of the pancreatic islet, cells of the GI tract, and in the CNS (pituitary). They inhibit a wide variety of endocrine and exocrine secretions, including TSH and GH from the pituitary, gastrin, motilin, VIP, glicentin, and insulin, ...