Abnormal secretion of vasoactive substances (i.e., histamine, kallikrein, serotonin) by carcinoid tumor.
Most common localization of tumor: small bowel, stomach, and ovaries.
Effects of Secreted Hormones
|Clinical manifestation||Coronary artery spasm, HTN, diarrhea||Hypotension, flusing, bronchoconstriction||Vasodilation, bronchoconstriction, cardiac arrhythmias|
- 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)
Monitors: A-line is useful because manipulation of the tumor can cause wide hemodynamic fluctuations.
CVL and PAC may also be helpful; consider TEE if altered cardiac function.
Induction: Etomidate or propofol can be used as long as hemodynamic stability is maintained. Succinylcholine should be avoided because of possible histamine release.
Intraoperative: All inhalation agents acceptable but desflurane may be preferable because of low hepatic metabolism in cases of liver metastasis of tumor.
Measure electrolytes frequently.
Volume expansion may be helpful with crystalloid or colloid.
Avoid drugs known to provoke release of mediators.
Octreotide 25–100 mcg should be used prior to tumor manipulation to attenuate hemodynamic effects.
Anesthetic Agents and Carcinoid
|Drugs provoking mediator release (Avoid)||Drugs not known to release mediators (Use)|
|Succinylcholine, mivacurium, atracurium, epinephrine, norepinephrine, dopamine, isoproterenol, thiopental, morphine||Propofol, etomidate, vecuronium, cisatracurium, rocuronium, sufentanil, alfentanil, fentanyl, remifentanil, volatile agents|
Hypotension should be treated with volume expansion and octreotide and not with catecholamines/sympathomimetics.
Hypertension: deepen anesthesia, then IV esmolol.
ICU with invasive hemodynamic monitoring for 48–72 hours.
Taper octreotide over 3–4 days.
Pain control necessary to prevent stress-induced release of mediators; avoid morphine.
Carcinoid crisis can be precipitated by stress, tumor necrosis, or surgical stimulation, as well as from anesthetic drugs such as succinylcholine.
Octreotide infusion at 50–100 mcg/h can be given with boluses of 25–100 mcg for treatment of crisis.
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, ...