Anesthesia for patients with carcinoid tumors

Published on 07/02/2015 by admin

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Last modified 07/02/2015

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Anesthesia for patients with carcinoid tumors

Michelle A.O. Kinney, MD, John A. Dilger, MD and Toby N. Weingarten, MD

Evaluation of carcinoid tumors

Carcinoid tumors are the most common gastrointestinal endocrine tumor, with an incidence of 3 per 100,000 per year in the United States. Carcinoid tumors arise from enterochromaffin cells (entero meaning gut and chromaffin because these cells share characteristics with chromaffin cells in the adrenal medulla) derived embryologically from epithelial stem cell precursors. Because these cells are not derived from the neural crest, they are more appropriately termed enteroendocrine than neuroendocrine. The site of origin of carcinoid tumors depends on the number of enterochromaffin cells within different organs—70% to 90% arise in the appendix, ileum, and rectum; up to 20% of tumors arise in the lungs; and less commonly, they can be found in the ovaries, thyroid, and pancreas. Enterochromaffin cells contain numerous membrane-bound neurosecretory granules composed of hormones and biogenic amines. The most prevalent compound is serotonin (80%-90% of the body’s stores), produced from its precursor, 5-hydroxytryptophan, but these cells can also produce corticotropin, histamine, dopamine, substance P, neurotensin, prostaglandins, and kallikrein. Stress of any kind can stimulate tumors to release their contents of these vasoactive substances into the circulation, resulting in mild symptoms to a full-blown carcinoid crisis.

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. The carcinoid syndrome occurs when these substances are secreted into the systemic venous system from a tumor that has metastasized to the liver (thus bypassing the portal circulation) or has originated in the lungs, ovaries, or thyroid. Clinical signs and symptoms of carcinoid syndrome include bronchoconstriction, episodic cutaneous flushing, abdominal pain, diarrhea, hemodynamic instability, hepatomegaly, hyperglycemia, and dysthymia.

Laboratory test results that support a diagnosis of carcinoid tumor, either primary or metastatic, include a 24-h urine test with more than 25 g of 5-hydroxyindoleacetic acid (5-HIAA), the metabolite of serotonin, or a positive serum chromogranin A (CgA) test. Serum CgA is a glycoprotein secreted with other hormones by enteroendocrine tumors and is 95% specific and almost 80% sensitive for the detection of carcinoid tumors.

In addition to performing a physical examination and history to identify associated signs and symptoms and conducting appropriate laboratory tests, a thorough heart evaluation is warranted, looking specifically for evidence of tricuspid regurgitation and pulmonary stenosis. Left-sided valvular lesions are uncommon and are usually associated with a bronchogenic tumor. Carcinoid-related valvular fibrosis has been thought to be due to longstanding exposure to elevated levels of serotonin, but other factors must be involved because serotonin inhibitors do not prevent the cardiac valvular fibrosis.

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