Ischemic Colitis - MColey

Ischemic Colitis - MColey - Ischemic Colitis Ischemic...

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Unformatted text preview: Ischemic Colitis Ischemic Colitis Marcelyn Coley Team IV Surgery Conference Mount Sinai Hospital Intestinal ischemia Intestinal ischemia Mesenteric ischemia ­ reduction in intestinal blood supply Acute Mesenteric Ischemia Most often involves SMA from emboli, arterial and venous thrombi, or vasoconstriction secondary to low flow Chronic Mesenteric Ischemia postprandial abdominal pain, marked weight loss caused by repeated transient episodes of inadequate intestinal blood flow AGA guideline: Intestinal Ischemia. Gastroenterology 2000; 118:951 Colonic ischemia After aortic or cardiac bypass surgery Certain systemic conditions vasculitides (eg, systemic lupus erythematosis, periarteritis nodosum) infections (eg, cytomegalovirus, E. coli O157:H7) coagulopathies (eg, protein C and S deficiencies, anti­thrombin III deficiency, APC resistance) Medications (eg, oral contraceptives) or illicit drugs (eg, cocaine) After strenuous and prolonged physical exertion (eg, long­distance running) After any major cardiovascular episode accompanied by hypotension With). Ischemic Colitis Ischemic Colitis COLONIC ISCHEMIA Most frequent form of mesenteric ischemia Commonly left colon Mostly elderly population Etiology Low­flow state (hypotension) Embolus (A­fib) Post MI (hypotension, mural thrombus) Post AAA reconstruction Closed loop construction ­ left side with intact ileocecal valve Volvulus Mesenteric Vein Thrombosis Catastrophic if not recognized Ischemic Colitis Ischemic Colitis Incidence: Thought to be underestimated because many mild cases may go unreported. In contrast, the incidence in patients undergoing abdominal aortic reconstructive procedures has been studied. Hunter and Guernsey (1988) reported that as many as 10% of such patients have some degree of ischemic colitis. Vascular Supply of the Colon Vascular Supply of the Colon Ischemic Colitis: Ischemic Colitis: Vascular Supply Superior mesenteric artery (SMA) Inferior mesenteric artery (IMA) Ileocolic artery – terminal ileum, cecum, appendix, prox ascending colon Right colic artery – ascending colon, hepatic flexure Middle colic artery – transverse colon Left colic artery – descending, transverse colon, splenic flexure Sigmoid arteries – sigmoid and descending colon Superior rectal artery – proximal rectum Collateral flow Marginal artery of Drummond – collateral connection between SMA and IMA along the mesenteric border IMA and internal iliac – supply good collaterals to the rectum Ischemic Colitis Ischemic Colitis Watershed areas 1. 2. Splenic flexure Rectosigmoid junction Most vulnerable during systemic hypotension Ischemic Colitis: Location of Ischemic Colitis: Location of ischemia by regions Other areas refer to combination of different regions. Data from: Reinus, JF, Brandt, LJ, Boley, SJ, Gastroenterol Clin North Am 1990; 19:319 Ischemic Colitis Ischemic Colitis Venous drainage Veins parallel their corresponding arteries SMV – drains small intestine, cecum, ascending, and transverse colon IMV – drains descending colon, sigmoid colon Superior rectal vein – rectum IMV fuses with splenic vein Ischemic Colitis Ischemic Colitis Pathophysiology Colonic ischemia usually result of a sudden and usually temporary reduction in blood flow insufficient to meet metabolic demands of discrete regions of the colon Occlusion Hypoperfusion (Low­flow state) Thrombus, embolus, atherosclerotic stenosis GI bleeding, hypotension, Nonocclusive mesenteric ischemia (NOMI) Mesenteric venous thrombosis Distal small bowel and prox colon Ischemic Colitis Ischemic Colitis Aortoiliac surgery Cardiopulmonary bypass Post­Myocardial infarction Hypotension, mural thrombus Obstruction or potentially obstructing lesions of the colon (carcinoma, diverticulitis, volvulus) Hemodialysis 1% to 7% develop colonic ischemia Typically nonocclusive due to underlying atherosclerosis, diabetes, and hemodialysis­ induced hypotension Vasculitides (systemic lupus erythematosis, periarteritis nodosum) Drugs (digoxin, tegaserod, alosetron, cocaine) Extreme exericise Acquired and hereditary thrombotic conditions Antiphospholipid antibodies, Factor V Leiden mutations, Protein C and S deficiency, Antithrombin III deficiency Ischemic Colitis Ischemic Colitis Colon receives less blood supply compared to the rest of the gi tract thus is vulnerable to hypoperfusion Vasospasm – a mechanism to redirect blood to cerebral circulation during hypotension Ischemic Colitis Ischemic Colitis Mechanism of Injury Hypoxia causes detectable injury to superficial mucosa within one hour Prolonged severe ischemia – necrosis of villous layer Leads to transmural infarction in 8 to 16 hrs Reperfusion injury – mediated by release of oxygen free radicals and neutrophil activation Ischemic Colitis Ischemic Colitis Clinical Manifestations Acute setting Rapid mild onset abdominal pain and tenderness over affected bowel (lower abdominal) Mild to moderate rectal bleeding or bloody diarrhea Ischemic Colitis Ischemic Colitis Presenting of symptoms 95% with abdominal pain 44% with nausea 35% with vomiting 35% with diarrhea 16% presented with blood per rectum Ischemic Colitis Ischemic Colitis Risk factors 78% ­ hypertension 71% ­ tobacco use 62% ­ peripheral vascular disease 50% ­ coronary artery disease Ischemic Colitis Ischemic Colitis Clinical Manifestations Thrombotic/embolic mesenteric occlusion present with sudden­onset severe mid­abdominal pain that is out of proportion to the physical findings typically have a history of chronic postprandial abdominal pain and significant weight loss. NOMI pain usually not as sudden as that noted with embolic or thrombotic occlusion: it is generally more diffuse and tends to wax and wane unlike the pain associated with occlusive disease, which tends to get progressively worse Ischemic Colitis Colonic vs. small bowel ischemia Acute colonic ischemia Acute mesenteric ischemia involving small bowel 90 percent of patients over age 60 Age varies with etiology of ischemia Acute precipitating cause is rare Acute precipitating cause is typical Patients do not appear ill Patients appear very ill Mild abdominal pain, tenderness present Pain is usually severe, tenderness is not prominent early Rectal bleeding, bloody diarrhea typical Bleeding uncommon until very late Colonoscopy is procedure of choice Angiography indicated Data from: Reinus, JF, Brandt, LJ, Boley, SJ, Gastroenterol Clin North Am 1990; 19:319. Ischemic Colitis Ischemic Colitis Clinical stages Hyperactive phase Paralytic phase Soon after initiating event, severe pain with frequent bloody, loose stools Pain diminishes, more continuous, and diffuse Abdomen more distended, tender, without BS Shock phase (10 to 20%) Massive fluid, protein, and electrolyte leakage through gangrenous mucosa Severe, shock and metabolic acidosis, may develop Rapid surgical intervention required Ischemic Colitis Ischemic Colitis Diagnosis Largely based on clinical setting Physical exam Laboratory Stool cultures for suspected infectious cause Increase serum lactate, LDH, CPK, or amylase Metabolic acidosis Elevated white count >20,000 Ischemic Colitis Ischemic Colitis Radiological imaging/Endoscopic studies Plain abdominal x­ray Contrast studies Computed Tomography May be normal initially Thickening of bowel wall in segmental pattern and mesenteric stranding Pneumatosis and gas in mesenteric veins in advanced stages Endoscopy Ischemic Colitis Ischemic Colitis Endoscopy of ischemic colitis may reveal continuous necrosis and mucosal friability that resembles ulcerative colitis (left panel); discrete ulcers with surrounding edema may also be seen (right panel). Courtesy of James B McGee, MD. Ischemic Colitis Ischemic Colitis Colonoscopy no evidence of peritonitis or perforation Preferred to contrast enemas, more sensitive in detecting mucosal lesions Segmental distribution, abrupt transition between injured and non injured mucosa, rectal sparing, and rapid resolution on serial endoscopy “single­stripe sign” – linear ulcer along longitudinal axis Biopsies may show non­specific changes (mimicking Crohn’s disease) Ischemic Colitis Ischemic Colitis Contrast studies Thumbprinting most suggestive on double contrast study seen early in disease In a small series of patients with mucosal ischemia 75% +thumbprinting, 60% longitudinal ulcers (source) Ischemic Colitis Ischemic Colitis Invasive studies – angiography, laparoscopy (dx unclear or means to follow patient postoperatively) Angiography (rarely helpful) Laparoscopy Particularly in elderly with comorbid disease and may not tolerate laparotomy “Second­look” to assess viability of remaining bowel Only serosal gut visualization, which may appear normal in early stages; progressive phase, dark peritoneal fluid, edematous bowel, or patchy hemorrhages, frank gangrene, or perforation may be present Magnetic Resonance Angiography, Duplex sonography – hardly ever required for colonic ischemia Ischemic Colitis Ischemic Colitis Differential Diagnosis Infectious colitis C. difficile, parasitic Inflammatory bowel disease Diverticulitis Radiation enteritis Solitary rectal ulcer syndrome Colon carcinoma Ischemic Colitis Ischemic Colitis Management Nonocclusive ischemia Supportive IVF, bowel rest, empiric antibiotics (mod to severe cases) NGT (ileus) Hold meds that can promote ischemia Optimize cardiac and pulmonary function Laparotomy with resection Clinical deterioration despite conservative therapy Intraoperative determination of bowel salvageability. ACS Principles and Practice Ischemic Colitis Ischemic Colitis Colonic infarction Requires urgent surgical intervention Bowel prep should not be given prior to surgery Right­sided ischemia/necrosis Left­sided involvement Proximal stoma and distal mucous fistula or Hartmann’s procedure Ostomy closure delayed 4 to 6 months Fulminating type (rare) Right hemicolectomy with primary anastamosis If perforation associated with peritonitis, resection with terminal ileostomy mucocutaneous fistula Total colectomy with end­ileostomy Many advocate a 2nd look with 12 to 24 h to document viability Mortality following large bowel infarction as high a 50 to 75% Prognosis Prognosis Most patients with non­occlusive ischemia improve within 1 or 2 days A minority develop long­term complications Segmental colitis or stricture ~15% develop severe gangrene 5­yr survival 70­86% those that survive surgical revascularization No randomized controlled trials Improved Outcome bv Identification of High­Risk Nonocclusive Mesenteric Ischemia, Aggressive Reexploration, and Delayed Anastomosis David Ward, MD et al. St. Louis, Missouri. Am J Surg. 1995 170:577­581 34 patients with NOMI Retrospective study over 7years Concluded that improved survival depended on identification of high­risk groups, aggressive re­exploration, and delayed intestinal anastamosis Ischemic Colitis Ischemic Colitis Summary Most frequent form of Mesenteric Ischemia Spectrum of conditions and predisposing factors Early recognition and aggressive treatment essential to survival ...
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This note was uploaded on 12/21/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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