Intestinal ischemia resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2]

Synonyms and keywords: Mesenteric ischemia, bowel ischemia

Overview

Intestinal ischemia are a heterogeneous group of diseases characterized by hypoxia of the small bowel and/or colon, which most commonly arises from occlusion, vasospasm, and/or hypoperfusion of the mesenteric vasculature.

Classification

Acute Mesenteric Ischemia

Acute mesenteric ischemia (AMI) includes superior mesenteric artery embolism (SMAE) (50%); nonocclusive mesenteric ischemia (NOMI) (20% to 30%); superior mesenteric artery thrombosis (SMAT) (15% to 25%); and superior mesenteric vein (SMV) thrombosis (5%). It is most commonly associated with compromise of the blood flow in the superior mesenteric artery (SMA) distribution affecting all, or portions of, the small bowel and right colon.

Chronic Mesenteric Ischemia

Chronic mesenteric ischemia (CMI) is usually referred to intestinal angina, where the splanchnic circulation is insufficient in meeting the functional demands of the gut, but there is no loss of tissue viability.

Colonic Ischemia

Colonic ischemia (CI) is the most common vascular disorder of the gut that includes reversible ischemic colopathy, transient ulcerating ischemic colitis, chronic ulcerating ischemic colitis, colonic stricture, colonic gangrene, and fulminant universal ischemic colitis.

Causes

Life Threatening Causes

Intestinal ischemia can be a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

• Arterial embolism
• Arterial thrombosis
• Hypercoagulable states
• Non-occlusive ischemia
• Cardiogenic shock
• Vasculitis
• Vasoconstrictors: Cocaine, ergot, vasopressin, or norepinephrine.
• Venous thrombosis

Management

The algorithm is based on the American Gastrointestinal Association guidelines for management of intestinal ischemia in adults.

Management of Acute Mesenteric Ischemia

Characterize the symptoms: ❑ Abdominal pain: ❑ Onset (sudden or insidious) ❑ Duration (persistent for more than 2-3 hours) ❑ Location (localized or generalized) ❑ Severity (often out of proportion to findings on physical examination) ❑ Nausea and vomiting ❑ Abdominal distention ❑ Bloody stools ❑ Mental status change Inquire about risk factors for AMI: ❑ Cardiovascular: ❑ Congestive heart failure ❑ Cardiac arrhythmias ❑ Recent myocardial infarction ❑ Valvular heart disease ❑ Previous H/O DVT, PVD, PE, vasculitis ❑ Recent hypovolemia ❑ Recent hypotension ❑ Cardiac surgery and dialysis ❑ Hypercoagulable states: ❑ Protein C deficiency and Protein S deficiency ❑ Antithrombin III deficiency ❑ Activated protein C resistance (APC) ❑ Paroxysmal nocturnal hemoglobinuria ❑ Myeloproliferative disease ❑ Intestinal angina: ❑ Chronic postprandial pain ❑ Aversion to eating ❑ Weight loss ❑ Sepsis, abdominal infections ❑ Blunt abdominal trauma ❑ Pancreatitis, splenectomy, and malignancy in the portal region ❑ Familial history of atheroembolism ❑ Smoking history

Assess volume status: ❑ General condition ❑ Thirst ❑ Pulse ❑ Blood pressure ❑ Eyes ❑ Mucosa Examine the patient: ❑ Abdomen: ❑ Abdominal distension ❑ Occult blood in the stool ❑ Signs of peritoneal inflammation (rebound tenderness and guarding) ❑ Bowel sounds (absent in bowel infarction) ❑ Cardiovascular system (murmur) ❑ Respiratory system ❑ Anorectal (bleeding) ❑ Signs of vasculitis

High clinical suspicion with known risk factors Resuscitate the patient: ❑ NPO ❑ Intravenous fluids ❑ Avoid vasoconstrictors and digitalis ❑ If required, use dobutamine, low-dose dopamine, or milrinone ❑ Correct predisposing or precipitating factors: ❑ Relieving acute congestive heart failure and hypotension ❑ Correction of hypovolemia ❑ Correction of cardiac arrhythmias ❑ Antibiotics for sepsis ❑ Monitor vitals every 1/2 to 1 hour Order tests (urgent): ❑ CBC: Leukocytosis ❑ Serum electrolytes ❑ ESR: Elevated ❑ D dimer: Elevated ❑ Serum lactate: Elevated ❑ Serum amylase ❑ ABG: Metabolic acidosis or metabolic alkalosis ❑ Serum alpha-glutathione S-transferase (alpha-GST): Elevated ❑ Urinary and plasma intestinal fatty acid-binding protein (I-FABP): Elevated ❑ Total serum protein and albumin ❑ Urinalysis ❑ BUN ❑ Creatinine ❑ Serum glucose

Plain abdominal X-ray (urgent)

Other causes ❑ Perforated peptic ulcer Or ❑ Gallbladder disease Or ❑ Pancreatitis Or ❑ Intestinal obstruction

History of DVT or familial hypercoagulable state

Treat accordingly

Yes

No

Dynamic CT scan ❑ Portal venous gas ❑ Pneumatosis intestinalis ❑ Bowel wall thickening Patient #1: CT images of patient with ischemic bowel demonstrates pneumatosis and portal venous gas

Peritoneal signs

Mesenteric venous thrombosis

No

Yes

Mesenteric angiography

Laprotomy

Normal findings

No persistent peritoneal findings

Persistent peritoneal findings

Observe

Laprotomy

Mesenteric venous thrombosis

Major arterial occlusion (non-embolic)

Minor arterial occlusion or embolic

Major embolus

Splanchnic vasoconstriction (no occlusion)

Management of Mesentric Venous Thrombosis

Mesentric venous thrombosis

Symptomatic acute mesentric venous thrombosis

Asymptomatic mesentric venous thrombosis ❑ Diagnosis made on a CT scan obtained for reasons other than abdominal pain

No persistent peritoneal findings

Persistent peritoneal findings

❑ No therapy Or ❑ Anticoagulation for 3-6 months

Immediate institution of anticoagulant therapy ❑ Low molecular weight heparin: ❑ 7-10 days ❑ Bolus of 80 U/kg, not to exceed 5000 U ❑ Infusion at 18 U/kg/h until full conversion to oral warfarin ❑ Monitor anticoagulation using activated partial thromboplastin time (aPTT) ❑ Oral warfarin: ❑ 3-6 months or for life in permanent hypercoagulable states ❑ Tailor the dose to maintain INR in the 2-3 range With or without thrombolytic therapy ❑ IV tissue plasminogen activator Or ❑ IV streptokinase Or ❑ IV urokinase

Laprotomy ❑ Initiate heparin preoperatively ❑ Resection for short ischemic segment and non-viable extensive ischemic segment ❑ Consider second-look procedure (re-exploration within 12-24 hours) ❑ Long term parental nutrition after resection ❑ Thrombectomy, heparin and papaverine for viable extensive ischemic segment with main vessel occlusion ❑ Heparin and papaverine for viable extensive ischemic segment with open or reconstituted main ❑ Warfarin prophylaxis

Laprotomy if peritoneal signs develop in due course

Management of Major and Minor Embolus

Major embolus

Minor arterial occlusion or embolus

No persistent peritoneal findings

Persistent peritoneal findings

No persistent peritoneal findings

Persistent peritoneal findings

Selected cases ❑ Contraindications to surgery ❑ Good perfusion of the vascular bed distal to the embolus after a vasodilator (tolazoline)

Continous papaverine infusion preopratively

Continous papaverine infusion Or Thrombolytic therapy Or Anticoagulants

Continous papaverine infusion

Yes

No

Exploratory laprotomy ❑ Embolectomy ❑ Resection of the infarcted bowel

Observe and repeat angiogram

Laprotomy ❑ Embolectomy ❑ Local resection

Continous papaverine infusion

Surgical embolectomy Or Thrombolytic therapy ❑ If presentation is within 12 hours of the onset of symptoms ❑ If thrombus is partially occluding or ❑ If thrombus is in one of the branches of the SMA or ❑ If thrombus is in the main SMA distal to the origin of the ileocolic artery

Continous papaverine infusion postoperatively

Angiogram normal

Stop the infusion and remove the catheter

Repeat angiogram

Repeat angiogram and possibly a second look operation in 24-48 hours

Observe

Management of Thrombus Occlusion and Nonocclusive Mesenteric Ischemia

Major arterial occlusion or thrombus

Nonocclusive mesenteric ischemia or splanchnic vasoconstriction

No persistent peritoneal findings

Persistent peritoneal findings

No persistent peritoneal findings

Persistent peritoneal findings

Angiographic evidence of collaterals

Continous papaverine infusion

Continous papaverine infusion preoperatively

Yes

No

Observe

Laprotomy with or without resection

SMA filling

Repeat angiogram

Continous papaverine infusion postoperatively

Good

Poor

Stop the infusion and remove the catheter

Observe

Laprotomy ❑ Continous papaverine infusion if possible ❑ Arterial reconstruction ❑ Resection of the infarcted bowel

Repeat angiogram and possibly a second look operation

Management of Chronic Mesenteric Ischemia

Characterize the symptoms: ❑ Abdominal pain: ❑ Recurrent acute episodes ❑ Dull, crampy ❑ Occurs shortly after meals and persists for 1-3 hours ❑ Variable intensity and location ❑ Increases in severity over weeks to months ❑ Fear of eating ❑ Early satiety ❑ Weight loss ❑ Nausea and vomiting Inquire about all the risk factors for AMI

Examine the patient: ❑ General condition ❑ Pulse ❑ Blood pressure ❑ Abdomen (distension, bowel sounds) ❑ Cardiovascular system (murmur) ❑ Respiratory system ❑ Anorectal

Diagnosis by clinical criteria ❑ Above mentioned positive history ❑ No other explanation for the abdominal pain Order tests (urgent): ❑ CBC: Leukocytosis ❑ Serum electrolytes ❑ ESR ❑ D dimer ❑ Serum lactate ❑ Serum amylase ❑ ABG ❑ Urinalysis ❑ BUN ❑ Creatinine ❑ Serum glucose

Screening tests ❑ Precibal and postcibal doppler ultrasound Or ❑ MRI angiography Or ❑ MRI oximetry Or ❑ Provocative balloon tonometry

Splanchnic angiography

Normal

Abnormal

Abnormal

Normal

Observe

Splanchnic angiography

Specific treatment

Observe

Poor surgical candidates

Good surgical candidates

Angioplasty with or without stent

Surgical revascularization

Management of Colonic Ischemia

Characterize the symptoms: ❑ Abdominal pain: ❑ Rapid onset ❑ Severe pain initially over the affected segment ❑ Pain usually diminishes, becomes more continuous, and diffuses ❑ Bloody diarrhea within 24 hours of the onset of abdominal pain ❑ Rectal bleeding within 24 hours of the onset of abdominal pain. ❑ Nausea and vomiting ❑ Dehydration ❑ Mental state change Inquire about the risk factors for colonic ischemia ❑ Cardiovascular: ❑ Cardiopulmonary bypass ❑ Aortoiliac instrumentation/surgery ❑ Myocardial infarction ❑ Valvular heart disease ❑ Previous H/O DVT, PVD, PE, vasculitis ❑ Hypotension ❑ Hypercoagulable states ❑ Obstructive lesions of the colon: ❑ Colon cancer ❑ Adhesion ❑ Rectal prolapse ❑ Fecal impaction or pseudoobstruction ❑ Strangulated hernia ❑ Diverticulitis ❑ Escherichia coli O157:H7 ❑ Cytomegalovirus infections ❑ Medications ❑ Alosetron ❑ Digitalis ❑ Diuretics ❑ Cocaine ❑ Estrogens ❑ Danazol ❑ NSAIDs ❑ Tegaserod ❑ Vasoactive substances ❑ Paclitaxel ❑ Carboplatin ❑ Sumatriptan ❑ Antipsychotics ❑ Simvastatin ❑ Pancreatitis ❑ Hemodialysis ❑ Strenuous and prolonged physical exertion ❑ Major vascular occlusion

Assess volume status: ❑ General condition ❑ Thirst ❑ Pulse ❑ Blood pressure ❑ Eyes ❑ Mucosa Examine the patient: ❑ Abdomen (distension, bowel sounds) ❑ Anorectal (bleeding) ❑ Cardiovascular system (murmur) ❑ Respiratory system ❑ Signs of vasculitis

Clinical suspicion of colonic ischaemia ❑ Above mentioned positive history ❑ No other explanation for the abdominal pain ❑ Other colonic pathology not responding to previous medications Order tests (urgent): ❑ CBC: Leukocytosis ❑ Serum lactate ❑ Serum amylase ❑ LDH ❑ CPK ❑ Serum electrolytes ❑ ESR ❑ D dimer ❑ ABG ❑ BUN ❑ Creatinine ❑ Serum glucose Order imaging (urgent): ❑ Barium enema: ❑ Pseudotumors ❑ Thumbprinting: Sign of bowel wall thickening ❑ CT of the abdomen ❑ Colonoscopy

Confirmed diagnosis Resuscitate the patient: ❑ NPO for 48-72 hours ❑ Intravenous fluids ❑ Avoid vasoconstrictors and digitalis ❑ If required, use dobutamine, low-dose dopamine, or milrinone ❑ Broad spectrum antibiotics ❑ Medications that can promote ischemia should be promptly discontinued ❑ Monitor vitals every 1/2 to 1 hour

Evolving peritoneal signs or clinical deterioration

Continued diarrhea, bleeding, protein losing colopathy for > 2-3 weeks

Stable

Laprotomy

Resection of the involved bowel

Repeat barium enema or colonoscopy in 1-2 weeks

Resection of the involved bowel

Segmental colitis

Normal

Symptomatic or Stricture formation or Recurrent fever or sepsis

Asymptomatic

Resection of the involved segment

Observe or Treat for inflammatory bowel disease

Do's

• A high index of suspicion in elderly patients with risk factors for intestinal ischemia is imperative for making a prompt diagnosis.
• Rapid diagnosis is essential to prevent the catastrophic events associated with delay in immédiate treatment leading to intestinal infarction.
• Aggressive hemodynamic support, monitoring in intensive care unit, correction of metabolic acidosis, initiation of broad spectrum antibiotics, and placement of a nasogastric tube for gastric decompression take priority over specific treatment.
• Hemodynamic stabilization should be achieved prior to arteriography.
• Stool cultures for Salmonella, Shigella, Campylobacter, Yersinia, E-coli O157:H7, and assay for stool toxins of Clostridium difficile should be considered in the appropriate clinical situation.
• Do aim at the prevention of future embolic events, typically with the long term use of warfarin.

Dont's

• Don't treat patients with severe diarrheal dehydration using 5% dextrose with 1/4 normal saline, as using solutions with lower amounts of sodium (such as 38.5 mmol/L in 1/4 saline with 5% dextrose ) would lead to sudden and severe hyponatremia with a high risk of death.
• Dont administer systemic anticoagulants to prevent thrombus formation or propagation in patients who are actively bleeding.
• Dont use opioids, anticholinergic and antidiarrheal agents in patients with severe colitis because of the potential to precipitate further complications.