1. Intestinal Ischemia Academic Half Day Dean Soulellis Gastroenterology

2. Intestinal Ischemia Intestinal ischemia is a bunch of different pathologies involving different organ within the GI tract Best to go anatomically Celiac trunk

3. Celiac Trunk/Axis Supplies the lower esophagus, stomach, D1, D2, sometimes D3, and liver/pancreas

4. SMA D2/D3, Jejunum, Ileum, cecum and ascending colon, and most of transverse colon

5. IMA Distal transverse colon to the proximal rectum

6. Causes of Ischemia Lack of blood flow Lack of Oxygen Thrombus (A or V) Embolus (A or V) Supply-demand mismatch (low flow states)

7. Intestines Protect Themselves Can tolerate 75% reduction in blood flow for up to 12 hours At any moment in time, 1 in 5 capillaries are open Able to extract oxygen efficiently in times of need

8. Irreversible Ischemia Eventually vasodilation of residual capillaries overwhelmed by ischemia Leads to vasoconstriction and necrosis Reperfusion injury

9. Intestinal Ischemia Mechanism is familiar to you Same thing occurs in the heart (thrombus or low-flow state), kidneys (thrombus or embolism or low-flow state), brain (thrombus or embolism), extremities, etc.

10. Clinical Features - Acute Severe acute abdominal pain Patient feels like vomiting The problem is usually arterial – embolus, thrombus, or low-flow state

11. Older Patients Often more indolent presentation – chronic thrombus formation in one of the main branches Possible cardiac embolic event Maybe painless in very elderly

12. Older Patients A third of the very elderly will present with confusion alone! IF painless with blood per rectum, might be low-flow state to the colon – NOMI (not “ischemic colitis”)

13. Younger Patients Usually arterial embolic More violent presentation Think vasoactive street drugs and arrhythias

14. Chronic Pain Consider mesenteric VENOUS thrombosis Conceptually similar to DVT Results in ongoing abdominal pain, more chronic Ask about history of DVT, hypercoagulable states, vasculitis, previous abdominal surgery or infection

15. Physical Exam Assess vitals Watch for unusual presentation in the elderly Abdomen may be benign early on, then progress to tender, then rigid Distention is a very bad sign

16. Physical Exam Look for bloody stool on rectal exam Watch for urgent need to evacuate colon In general, keep an eye out for signs of sepsis

17. Labs Majority have elevated WBC, but this is not specific or sensitive Neither are amylase or phosphate Elevated lactic acid is important to note – signified transmural process, probable real ischemia in progress Not usually elevated in NOMI – process is not usually transmural

18. Imaging - AXR Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

19. Imaging - AXR Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

20. Imaging - AXR Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

21. Imaging - AXR Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

22. CT Scan (CTA w/V phase) Best imaging modality to consider up front Demonstrates pneumatosis in the wall Demonstrates thrombus or embolus Demonstrates embolic infarction of other organs

23. Management Resuscitate ASAP Broad spectrum antibiotics given immediately STRAIGHT TO SURGERY IF – Perforation on AXR – High suspicion and patient unstable (acute abdomen) – CT = necrotic bowel

24. Management If no perforation, but clinical suspicion remains high, FORMAL ANGIOGRAM If CT demonstrates intestinal ischemia with no necrosis, FORMAL ANGIOGRAM

26. Papaverine Opioid derivative Injected directly to the affected vasospastic area to improve blood flow Applications are ARTERIAL THROMBUS, EMBOLUS, OR NOMI ONLY For NOMI, can only be used once patient is volume resuscitated and hemodynamics fixed, or risk worsening of ischemia

27. Thrombolysis Another option for arterial thrombus with impending intestinal necrosis in poor surgical candidates Can precede surgery

28. Mesenteric Vein Thrombosis To recap, often a problem with some chronicity Less violent presentation (although acute DVT is possible and very serious) Consider hypercoagulable states, previous history of DVT (more than 60%), previous abdominal surgery or infection, inflammatory conditions of the abdomen (vasculitis, IBD, etc)

29. Mesenteric Vein Thrombosis Some interesting facts: – MVT due to hypercoagulable states starts in smaller vessels and extends into larger vessels – MVT due to cirrhosis, cancer, or surgery does the reverse Chronic MVT, especially of the portal trunk can result in varices (splenic vein thrombosis or eventual secondary cirrhosis of the liver from lack of portal nutrition)

30. MVT - Diagnosis CT-angiography is the imaging modality of choice Image demonstrates portal vein thrombosis

31. MVT - Management If ACUTE, then triage based on presentation – If acute abdomen, assess vitals, urgent CTA, and consider surgery if question of intestinal viability – If stable, then heparin x 7 days with Coumadin x 3- 6 months – If hypercoagulable or repeat event, then consider lifelong Coumadin

32. MVT - Management If CHRONIC (and asymptomatic), then endoscopy to screen for varices and do nothing – Collaterals have usually formed and taken care of the problem – Coumadinization carries more risk of bleeding than benefit at that point

33. NOMI In the ER we call this “ischemic colitis” Small arterial arcades with mini-thrombii and poor flow Precipitated by some cardiovascular disturbance (atrial fibrillation, CHF, overmedicated on antihypertensives, sepsis, etc)

34. Diagnosis Patients usually come with a history of crampy lower quadrant pain with bloody stools, on/off Discrete episodes Lasts hours to days Problem usually self-limited Medical history usually shows: over age 65, CAD, PVD, HTN, DM, lipidemia, etc.

35. Physical, Labs Usually patient normal Blood loss typically minimal, although in certain cases can be severe DRE is mandatory CBC, Lactic acid, renal function, electrolytes, liver enzymes and lipase Imaging usually restricted to CT (exclude diverticulitis) only

37. Management Controversy as to whether to start antibiotics Supportive management Early endoscopy Biopsy Watch for signs of deterioration over 48 hours Optimize hemodynamics, referral to cardiology, etc