Carcinoid syndrome

Carcinoid tumors typically secrete excessive amounts of the hormone serotonin (although they may secrete many hormones). They arise from neuroendocrine cells throughout the body. Most commonly from organs derived from the primitive gut (90% come from distal ileum or appendix).

Serotonin causes vasodilation, increased blood clotting (stimulation of platelet aggregation).

It should be noted that because the vasoactive substances contained in enterochromatin cells are cleared from the circulation by the liver, carcinoid tumors that are isolated to the gastrointestinal tract usually do not result in the systemic manifestations of the carcinoid syndrome. Thus, Malignant Carcinoid Syndrome typically occurs when tumor spreadsto the liver and beyond – vasoactive substances escape hepatic degradation, excessive production of serotonin both lead to red hot flushing of face, severe and debilitating diarrhea, and asthma attacks (tachykinins).

Surgical Treatment

May offer complete and permanent cure

• Hepatic resection for accessible areas of liver
• Distal ileum – Right hemicolectomy
• Appendix – Tumors < 1.5 cm appendectomy
• Rectum – <1.5 cm local resection, >1.5 cm abdominoperineal resection
• Chemoembolization of liver lesions

Anesthetic Considerations

History

• Some develop right heart problems due to tricuspid stenosis from serotonin action
• Other common problems – Asthma, wheezing, palpitations, hypotension, dizziness

Physical

• Pay attention to: heart murmur, asthma-like symptoms, pellagra, electrolyte deficieny/dehydration from diarrhea, hepatomegaly (from metastasis)
• Carcinoid heart disease
• Typically right side of heart
• Fibrous deposits on valvular endocardium
• Thickening of endocardium of cardiac chambers

Labs

• Measurement of serotonin metabolite 5-HIAA in 24 hr urine
• 25 mg/day of 5-HIAA is diagnostic

Goals

Prevention of Mediator release

• Preoperative Stress (use anxiolytic without histamine relating properties
• Response to intubation
• Inadequate analgesia
• Hypotension / Hypertension
• Intraoperative handling of tumor
• Histamine releasing drugs (probably should be avoided in patients with carcinoid tumors, although these drugs have been used frequently in the past without complications)

Diagnosis

• Severe hypotension/hypertension
• Flushing
• Bronchospasm
• Hypercoagulability

Treatment

• Octreotide (Somatostatin) immediately available– high affinity for somatostatin receptor that may help relieve vasoactive symptoms and restore hemodynamic stability
• Ondansetron – Anti-serotonin action with potential benefit
• Immediate availability of vasopressors (phenylephrine), vasodilators

Although phenylephirne can be used safely in these patients, beta-adrenergic agents such as epinephrine can stimulate the release vasoactive hormones from the tumor and exacerbate hypotension. It should be noted that the action of beta-adrenergic agents can be blunted if the patient has received an adequate dose of octreotide. Nevertheless, the primary treatment for hypotension in patients with carcinoid syndrome should be IV fluids, ocreotide, and phenylephrine (if necessary). The use of beta-adrenergic agents should be reserved for situations when the cause of hypotension is unrelated to the tumor. They should always be used cautiously.

Note: consider invasive monitoring