bowel ischemia.pptx

bowel iscehmia

1. Bowel Ischemia Dr. Abdullah Al Huwaiyshil R1 – Urology resident King Fahad Hospital Hofuf

2. Outline Types Anatomy Pathophysiology Acute Mesenteric Ischemia Mesenteric Vein Thrombosis Focal Segmental Ischemia Colon Ischemia Chronic Mesenteric Ischemia

3. Types TYPE FREQUENCY (%) Colon ischemia 75 Acute mesenteric ischemia 25 Focal segmental ischemia <5 Chronic mesenteric ischemia <5

4. Anatomy – Celiac Axis Supplies stomach, duodenum, pancreas, and liver Three branches: left gastric, common hepatic, splenic Common hepatic: gastroduodenal , right gastroepiploic , anterior superior pancreaticoduodenal Splenic: pancreatic and left gastroepiploic

5. Anatomy – Superior Mesenteric Artery (SMA) Anterior and posterior inferior pancreaticoduodenal Middle colic Right colic Ileocolic

6. Anatomy – Inferior Mesenteric Artery (IMA) Left colic Sigmoid branches Superior rectal Supply distal transverse to proximal rectum Distal rectum: internal iliac

7. Pathophysiology Bowel can tolerate 75% reduction of blood flow and oxygen consumption for 12 hours Collaterals open immediately After hours, vasoconstriction reduces collateral flow Hypoxia, reperfusion injury Microvascular injury

8. Acute Mesenteric Ischemia CAUSE FREQUENCY (%) SMA embolus 50 Nonocclusive mesenteric ischemia 25 SMA thrombosis 10 Mesenteric venous thrombosis 10 Focal segmental ischemia 5

9. Clinical Features Acute abdominal pain Rapid and forceful bowel evacuation Pain out of proportion to exam Unexplained abdominal distention (sign of infarction) or GI bleeding Physical findings worsen with progressive loss of bowel viability Infarction: 70-90% mortality

10. Diagnosis Labs 75% have WBC > 15 50% have metabolic acidosis Plain films Poorly sensitive (30%) and nonspecific Formless loops of small intestine Ileus, thumbprinting , pneumatosis Portal or mesenteric vascular gas CT Colon dilatation Bowel wall thickening Lack of enhancement of arterial vasculature Ascites CT angiography Better evaluation of vessels Selective mesenteric angiography Gold standard Prompt laparotomy if angiography not available

11. Portal Gas

12. Treatment General Resuscitation, Broad-spectrum antibiotics Superior Mesenteric Artery Embolus Cardiac origin Major: proximal to ileocolic Intra-arterial papaverine Surgical revascularization Minor and no peritoneal signs Intra-arterial papaverine (or thrombolytics ) Anticoagulation

13. SMA Embolus Pre and post treatment

14. Treatment Nonocclusive Mesenteric Ischemia Vasoconstriction from preceding cardiovascular event Angiography Narrowing of SMA branch origins Irregularities in intestinal branches Spasm of arcades Impaired filling of intramural vessels SMA infusion of papaverine for 24 hours Surgery if peritoneal signs are present

15. Treatment Acute Superior Mesenteric Artery Thrombosis Severe atherosclerotic narrowing Often superimposed on chronic mesenteric ischemia Demonstrated on aortography Management same as SMA embolism

16. Mesenteric Vein Thrombosis Age: mid-60s to 70s 20% mortality Manifest as colon ischemia, acute mesenteric ischemia, or focal segmental ischemia Causes Arterial hypertension Neoplasms Coagulation disorders Estrogen

17. Mesenteric Vein Thrombosis Acute Pain out of proportion to exam, n/v Lower GI bleeding suggests infarction Diagnosis CT is study of choice (finds >90%) Mesenteric arteriography Slow or absent filling of mesenteric veins Failure of arterial arcades to empty Prolonged blush in involved segment Treatment Incidental: up to six months of anticoagulation (AC) Peritonitis: surgery, papaverine , post-op heparin No peritoneal signs: heparin followed by 3-6 mos AC

18. Mesenteric Vein Thrombosis Subacute Abdominal pain for weeks to months but no infarction Chronic Asymptomatic May develop GI bleeding from varices Treatment: control bleeding

19. Focal Segmental Ischemia Involves small bowel Causes Atheromatous emboli Strangulated hernias Immune complex disorders Trauma Segmental venous thrombosis Radiation therapy Oral contraceptives Usually adequate collaterals to prevent infarction Presentation: enteritis, stricture, acute abdomen Chronic can resemble Crohn's

20. Focal Segmental Ischemia Radiologic studies Smooth tapered stricture Abrupt change to normal distally Dilated proximally Treatment: resection

21. Colon Ischemia TYPE FREQUENCY (%) * Reversible colopathy and transient colitis >50 Transient colitis 10 Chronic ulcerating colitis 20 Stricture 10 Gangrene 15 Fulminant universal colitis <5

22. Colon Ischemia Most common form of intestinal ischemia 7.2 cases per 100,000 person-years Female predilection Most > 60 years old Young pt : vasculitis , coagulation disorders, cocaine, medications Right colon ischemia May have small intestinal ischemia

23. Medications Penicillins Alkaloid and taxanes Constipation-Inducing Agents Pseudoephedrine Diuretics Oral contraceptive pills Amphetamines (R sided) Cocaine (L sided) Kayexelate Magnesium citrate Sodium phosphate Bisacodyl Glycerin enemas NSAIDs Sumatriptan Alosetron

24. Pathology Mild: mucosal and submucosal hemorrhage and edema More severe: ulcerations, crypt abscesses, pseudopolyps , pseudomembranes , iron-laden macrophages, submucosal fibrosis (stricture) Most severe: transmural infarction

25. Clinical Features Sudden cramping Mild left lower quadrant pain Urgent desire to defecate Hematochezia within 24 hours Location: Sigmoid 23% Descending-to-sigmoid 11% Cecum-to-hepatic flexure 8% (worse prognosis) Descending 8% Pancolonic 7%

26. Diagnosis CT scan If nonspecific, colonoscopy within 48 hours Colon single-stripe sign Line of erythema with erosion or ulceration along the longitudinal axis of the colon Milder course

27. Colonoscopy

28. Treatment NPO, IVF, antibiotics EKG, Holter , echo Colonic infarction Laparotomy and resection Serosa can be misleading Segmental Ulcerating Colitis Recurrent fevers and sepsis Continuing or recurrent bloody diarrhea Persistent or chronic diarrhea with protein-losing colopathy Treat by resection

29. Treatment Ischemic Stricture Dilation or resection  Universal Fulminant Colitis Colectomy with ileostomy Isolated Ischemia of the Right Colon Check CTA for concurrent AMI Carcinoma/Obstructive Lesions (<5%) Lesion distal, increased intracolonic pressure proximal Irritable Bowel Syndrome Colon ischemia 3.4 to 3.9x more common ?Hypersensitivity of the colonic vasculature Complicating Aortic Surgery Up to 7% of surgeries (60% for ruptured aneurysm) Colonoscopy within 2-3 days if high risk Ex: ruptured aneurysm, prolonged cross-clamping time, post-op diarrhea

30. Chronic Mesenteric Ischemia “Intestinal angina” Mesenteric atherosclerosis Pain from small bowel ischemia Blood stolen to meet increased gastric demand from food

31. Clinical Features Gradual cramping discomfort within 30 minutes of eating, resolves over hours Fear of eating, weight loss Nonhealing antral ulcers without H. pylori 1/3 to ½: cardiac, cerebral, peripheral vascular disease Exam Abdomen soft and nontender Bruit common but nonspecific

32. Diagnosis Gastric tonometry exercise testing (GET) NG tube and arterial line Patient on PPI Obtain gastric juice and arterial blood fasting, during, after exercise Measure gastric-arterial P co 2 gradients Increase after exercise indicates ischemia Combine with duplex U/S Angiography Should show occlusion of ≥2 splanchnic arteries Does not make diagnosis in itself

33. Treatment Revascularization Need occlusive involvement of ≥2 major arteries Surgical if healthy Otherwise percutaneous +/- stent

34. R eferences U ptodate

35. T hank you ..