Intestinal Ischemia

Academic Half DayDean Soulellis

Gastroenterology

Intestinal Ischemia

• Intestinal ischemia is a bunch of different pathologies involving different organ within the GI tract

• Best to go anatomically

• Celiac trunk

Celiac Trunk/Axis

• Supplies the lower esophagus, stomach, D1, D2, sometimes D3, and liver/pancreas

SMA

• D2/D3, Jejunum, Ileum, cecum and ascending colon, and most of transverse colon

IMA

• Distal transverse colon to the proximal rectum

Causes of Ischemia

• Lack of blood flow• Lack of Oxygen• Thrombus (A or V)• Embolus (A or V)• Supply-demand

mismatch (low flow states)

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

Irreversible Ischemia

• Eventually vasodilation of residual capillaries overwhelmed by ischemia

• Leads to vasoconstriction and necrosis

• Reperfusion injury

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.

Clinical Features - Acute

• Severe acute abdominal pain

• Patient feels like vomiting

• The problem is usually arterial – embolus, thrombus, or low-flow state

Older Patients

• Often more indolent presentation – chronic thrombus formation in one of the main branches

• Possible cardiac embolic event

• Maybe painless in very elderly

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”)

Younger Patients

• Usually arterial embolic

• More violent presentation

• Think vasoactive street drugs and arrhythias

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

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

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

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

Imaging - AXR

• Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

Imaging - AXR

• Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

Imaging - AXR

• Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

Imaging - AXR

• Normal > “Thumbprinting” > Pneumatosis of the intestinal wall or the blood vessel

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

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

Management

• If no perforation, but clinical suspicion remains high, FORMAL ANGIOGRAM

• If CT demonstrates intestinal ischemia with no necrosis, FORMAL ANGIOGRAM

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

Thrombolysis

• Another option for arterial thrombus with impending intestinal necrosis in poor surgical candidates

• Can precede surgery

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)

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)

MVT - Diagnosis

• CT-angiography is the imaging modality of choice

• Image demonstrates portal vein thrombosis

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

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

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)

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.

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

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