2022年医学专题—缺血性肠病(1).ppt

Ischemic Colitis,Ri 陳宏彰,第一页，共三十页。,Reference books,Harrisons online 15thMarx:Rosens Emergency Medicine:Concepts and Clinical Practice,5th ed.,Copyright 2002 Mosby,Inc,第二页，共三十页。,Ischemic Colitis,Ischemia of the colon most often affects the elderly(90%of patients 60 y/o).Ischemic colitis is almost always nonocclusive.(emboli are the most common cause of acute mesenteric ischemia)Shunting of blood away from the mucosa may contribute to this condition,but the mechanism is unknown.,第三页，共三十页。,Ischemic Colitis,Most patients ischemia occurs secondary to arteriolar shunting,spasm,or poor perfusion of mucosal vessels.Most cases involve the splenic flexure,which is supplied by end-arteries.The rectum is usually spared,because its blood supply is different from the rest of the colon and less dependent on the inferior mesenteric artery.,Marx:Rosens Emergency Medicine:Concepts and Clinical Practice,5th ed,第四页，共三十页。,Types of Ischemic Colitis,Acute fulminant ischemic colitis Subacute ischemic colitis,HARRISONS ONLINE 15TH,第五页，共三十页。,Types of Ischemic Colitis,Marx:Rosens Emergency Medicine:Concepts and Clinical Practice,5th ed,第六页，共三十页。,Acute fulminant ischemic colitis manifestations,The onset is characteristically acute,with generalized lower abdominal pain,usually in the left lower quadrant,followed within 24 hours by bloody diarrhea or rectal bleeding.Dilation of the colon and physical signs of peritonitis are seen in severe cases.With the gangrenous type,both symptoms and signs progress rapidly.,第七页，共三十页。,Acute fulminant ischemic colitis Diagnostic Strategy,No specific serum markers proven in the diagnosis of intestinal ischemia.Abdominal films may reveal thumbprinting from submucosal hemorrhage and edema.*(barium enema is contraindicated in cases of gangrenous ischemic colitis because of the risk of perforation),第八页，共三十页。,thumbprinting,第九页，共三十页。,Acute fulminant ischemic colitis Diagnostic Strategy,Sigmoidoscopy or colonoscopy may detect ulcerations,friability,and bulging folds from submucosal hemorrhage.(Colonoscopy is preferred over sigmoidoscopy)The segmental distribution and rectal sparing of the disease process are suggestive but are not diagnostic.,第十页，共三十页。,Colonoscopic view showing marked erythema and exudate in sigmoid colon,第十一页，共三十页。,Endoscopic view of mucosal edema,exudates,and ulcerations in sigmoid colon,第十二页，共三十页。,Endoscopic image of descending colon showing severe colitis with pneumatosis intestinalis.,第十三页，共三十页。,Acute fulminant ischemic colitis Diagnostic Strategy,Angiography is not helpful in the management of patients with presumed ischemic colitis because a remediable occlusive lesion is very rarely found.CT scan is normal in early stages of bowel infarction,although it may show nonspecific findings such as bowel wall thickening and pneumatosis.,第十四页，共三十页。,CT showing left sided colonic thickening.,第十五页，共三十页。,Pneumatosis Intestinalis,第十六页，共三十页。,Pneumatosis Intestinalis,第十七页，共三十页。,Acute fulminant ischemic colitis management,When ischemic colitis is suspected,a surgeon should be consulted.Gangrenous ischemic colitis or evidence of perforation requires immediate surgery as soon as the patient is stabilized.,第十八页，共三十页。,management,Vasopressors should be avoided,if possible.Low blood-flow states(hypotension)should be aggressively reversed.,第十九页，共三十页。,Types of Ischemic Colitis,Acute fulminant ischemic colitis Subacute ischemic colitis,第二十页，共三十页。,Subacute ischemic colitis manifestations,It produces lesser degrees of pain and bleeding,often occurring over several days or weeks.The left colon may be involved,but the rectum is usually spared because of the collateral blood supply.,第二十一页，共三十页。,Subacute ischemic colitis management,Subacute Ischemic colitis without evidence of peritonitis or perforation is generally self-limited and requires only conservative management,including bowel rest,parenteral fluids,and antibiotics.,第二十二页，共三十页。,Subacute ischemic colitis management,Most cases of nonocclusive ischemic colitis resolve in 2 to 4 weeks and do not recur.Surgery is not required except for obstruction secondary to postischemic stricture.,第二十三页，共三十页。,Differential Considerations,Ischemic colitis often mimics infectious colitis,inflammatory bowel disease,or even colon carcinoma.Many cases of colitis in the elderly once considered to be Crohns disease or ulcerative colitis in retrospect were really colonic ischemia.,第二十四页，共三十页。,Differential Considerations,The features considered atypical in inflammatory bowel diseases,such as 1.segmental distribution of the disease,infrequent rectal involvement,2.high rate of spontaneous recovery,low rate of recurrence,3.lack of adequate response to usual inflammatory bowel disease therapy,4.frequent progression to fibrotic stenosis with delayed obstructionThe features above are now recognized as characteristic of colonic ischemia.,第二十五页，共三十页。,Differential Considerations,Always consider the diagnosis of ischemic colitis whenever contemplating the diagnosis of inflammatory bowel disease