Introduction
Formidable dz - mortality 30-90%
Requires:
- High index of suspicion
- Aggressive Resuscitation
- Expeditious Operative Management
- Diligent Post-operative care
Early Diagnosis = Key to Survival (~2/3 misdiagnosis rate)
Anatomy
SMA – critical vessel
SMA had a less angled takeoff from aorta and is therefore more likely to receive emboli
Duodenum ~ 20 cm
Jejunum ~ 100 cm
Ileum ~ 150 cm
- More versatile
- Greater absorptive function
Watersheds
Griffith's point - between middle colic (SMA) and left colic (IMA)
Sudek's Point - between superior hemorrhoidal (IMA) and middle/inferior hemorrhoidal (iliac/pudendal)
Etiology
SMA Embolization (50%); 60-70% mortality
SMA Thrombosis (30%); 60-90% mortality
Non-Occlusive Ischemia (10-15%); 70% mortality
Mesenteric Venous Thrombosis (5-10%); 30% mortality
Presentation
Acute Onset
Mid-abdominal
Crampy progressing to severe constant
50% N,V
33% diarrhea, 25% bloody or Heme +
PAIN OUT OF PROPORTION to exam
Leukocytosis in 90%
Mild Hyperamylasemia in 50%
Progresses to Lactic Acidosis/Sepsis & Peritoneal Signs (mortality ~90% if get to this point)
Diagnosis
Clinical
CT
Angiography
Portal Venous Gas
Initial report in 1955
Initially = OR Indication
CT & US more sensitive
Portal venous gas is peripheral (<2cm from capsule), pneumobilia is central
Mechanisms:
- gas forming bacteria --> mucosal defects or translocation --> gas in bowel wall --> gas in portal venous system
- Bowel distention --> mechanical dissection of gas through mucosa
Etiologies:
Operation mandatory: mesenteric ischemia, obstruction, intra-abdominal infection (appendicitis, diverticulitis)
Operation optional: inflammatory bowel disease, s/p biliary manipulation/scope, s/p liver transplant, pseudo-obstruction
Management
If not OR, treat underlying cause
Pneumatosis Intestinalis
Presence of Gas in Bowel Wall
Described in 1754
Pathogenesis
- Gas forming bacteria --> mucosal defects or translocation --> gas in bowel wall
- Bowel distention --> mechanical dissection fo gas through mucosa --> gas in bowel wall
- High pulmonary pressures --> mediastinal gas --> retroperitoneal gas --> gas in bowel wall
Etiologies
Non-operative causes:
- Pulmonary (asthma, bronchitis, emphysema, pulmonary fibrosis, PEEP, cystic fibrosis),
- systemic disease (scleroderma, lupus, AIDS),
- Iatrogenic (barium enema, jejunoileal bypass, jejunostomy tubes, postsurgical anastomosis, endoscopy),
- medications (corticosteroids, chemotherapeutic agents, lactulose, sorbitol, voglibose),
- Organ transplant (bone marrow, kidney, liver, cardiac, lung, graft versus host),
- Primary pneumatosis (idiopathic [up to 15% of cases and usually involves the colon], pneumatosis cystoides intestinalis)
- Intestinal causes (intestinal pseudoobstruction, enteritis, peptic ulcers, bowel obstruction, adynamic ileus, inflammatory bowel disease, ulcerative colitis, crohn's disease, leukemia, whipple's disease, intestinal parasites, collagen vascular disease [especially scleroderma])
Operative Causes:
- Intestinal ischemia
- Mesenteric vascular disease
- Intestinal obstruction (especially strangulation)
- Enteritis
- Colitis
- Ingestion of corrosive agents
- Toxic megacolon
- Trauma
Additional XR Findings suggestive of Op Need
- Thickened Bowel Wall
- Absent Mucosal enhancement
- Intense Mucosal enhancement
- Ascites
- Mesenteric or Portal Venous Gas
- Confinement of air to one vascular distribution
*But not necessarily free air (can occur just due to ruptured pockets)
Bubbly pattern (most common), linear pattern (usually operative cause), circular pattern (usually benign pneumatosis cystoides intestinalis)
More easily seen on lung windows
Independent predictors of pathologic pneumatosis
Lactate >2.0 (OR 4.3)
Hypotension or pressor use (OR 5.1)
Peritonitis (OR 4.7)
Acute kidney injury (OR 3.4)
Active mechanical ventilation (OR 3.3)
Absent bowel sounds (OR 2.8)
Treatment
Goal Directed Resuscitation
Early (< 6hr) achievement of ScvO2 > 70% in Septic Pts associated c 20% reduced mortality
optimizing CVP, MAP, Hgb, achieved target ScvO2 in 95%, VRS 60% c standard therapy
Remember higher target CVP (12-15) indicated with: mechanical ventillation, known decreased ventricular compliance, abdominal compartment syndrome, diastolic dysfunction, known pulmonary artery hypertension
Angiography
Diagnostic in pt without acute abd or sepsis
Differential Dx – with risk of Non-occlusive ischemia
Aid in Planning Surgery
Questionable Role for On-Table Angio
To facilitate post-op Papaverine
SMA Embolization
Most common cause (50%) of acute mesenteric ischemia
SMA>Celiac due to less acute angle of takeoff from aorta
Typically embolus lodges distal to middle colic and initial jejunals --> proximal small bowel and transverse colonic sparing
Arterio-arterial emboli tend to be smaller and therefore more often cause segmental loss
Etiologies
Cardiac
- mural thrombus (a.fib, etc...)
- Valvular vegetations (rheumatic heart disease, endocarditis, etc...)
Arterial
- AAA
- Catheter manipulation
Operative Intervention
Aggressive Resuscitation
Prep Leg
Have vascular instruments
Expeditious Exploration
Resection of grossly infarcted bowel
+/- Re-vascularization with embolectomy
Anticoagulation
+/- Second Look
Determination of Bowel Viability
- Clinical judgement (color, bleeding, peristalsis): 82% sensitive, 91% specific, 89% accurate
- Fluoroscein: 80-100% sensitive, 80-100% specific, 80-100% accurate
- Doppler: 65% sensitive, 88% specific, 84% accurate
- Possible role for indigo-cyanine green SPY elite
Revascularization
3 or 4 embolectomy catheter proximal, 2 or 3 distal (vs "milking" distally)
Prognosis after Embolectomy
1993 Spanish Report with 21 cases - duration of symptoms vs. intestinal viability: <12 hrs - 100%; 12-24 hrs - 56%; >24 hrs - 18%
Flushing with papaverine after embolectomy seems to help offset the secondary vasoconstriction
2nd Look
Avoid deferred anastamoses
Avoid (if feasible) leaving under 150 cm
Avoid multiple anastamoses
Timing: 12-24 hr or if the pt declares the need
SMA Thrombosis
~ 30% of Acute Mesenteric Ischemia Cases
Mech: Acute thrombosis of pre-existing plaque during a low flow state or intraplaque hemorrhage
Prior Sx of: postprandial pain, food fear, weight loss
Operative management
Exposure of Supraceliac aorta
Longitudinal Arteriotomy
Endovascular Treatment
Lytics
Stenting
Does not address/eval bowel viability
Takes time
Best suited for chronic/partial occlusions
Nonocclusive Mesenteric Ischemia (NOMI)
10-15% of Acute Mesenteric Ischemia Cases
Caused by primary splanchnic vasoconstriction- Shock, post CABG, vasoconstrictors (pressors, digoxin), dialysis
Normal splanchnic blood flow = 10% of cardiac output, normal autoregulation after large meal -->45% of cardiac output
70% Mortality
DX: Angiography - pruned branch appearance, string of sausages sign
Treatment
Hemodynamic Stabilization
Intra-arterial Papovarine: initiate 30-60 mg/hr, +/- recheck angio after 30 minutes, continue for 24 hours then recheck angio
Can cause hypotension. Can’t run with heparin
Anticoagulation not typically needed
Mesenteric Venous Thrombosis
5 – 10% of Acute Mesenteric Ischemia cases
Better Prognosis
Etiologies:
-Direct injury (abdominal trauma, postsurgical, intra-abdominal inflammatory states, peritonitis and abdominal abscess)
-Local venous congestion or stasis (portal hypertension/cirrhosis of the liver, congestive heart failure, hypersplenism)
-Hypercoaguable states
~50% with prior history of DVT or PE
Diagnosis
CT 90% Sensitive - central lucency in vein, vein enlargement, bowel wall thickening
Venous Phase Angio
Mesenteric Duplex
Treatment = Anticoagulation
Indications for OR: persistent sepsis, thickened bowel and ascites with clot on CT
Tends to cause segmental infarction
Portal Vein Thrombosis
Etiologies
- Cirrhosis
- HCC
- Hypercoagulability
- Extrinsic compression (eg Pancreatic cancer)
- OCPs
- Intra-abdominal infection (pyelphlebitis)
Diagnosis
CT
Doppler
MRI
Venous Phase Angiography
Treatment
Often resolves spontaneously
Anticoagulation
+/- antibiotics
Address underlying cause
Complications
Portal hypertension
Mesenteric Ischemia
Hepatic Vein Thrombosis (Budd-Chiari Syndrome)
Etiologies
Hypercoagulable states
Pregnancy
OCPs
Myeloproliferative Disorders (see in 23%), most common polycythemia vera
Malignancy (eg HCC, Adrenocortical, renal cell)
Liver abscess
Typically seen in young/middle aged females (67% female, median age 35)
Presentation
Acute (20%) fulminant liver failure
Subacute (40%) liver failure
Chronic - cirrhoiss, portal hypertension
With acute and subacute you see 84% with ascites and 76% with hepatomegaly
Diagnosis
Doppler
CT
MRI
Venography
Liver biopsy
Treatment
Angioplasty
Lytics
TIPS
Portasystemic shunts
Liver transplant
Colonic Ischemia
Most common form of intestinal ischemia
Wide Spectrum: Transient colitis, chronic colitis, stricture, gangrene
IMA distribution is more responsive to medical management
Most commonly located in descending and sigmoid colon - watershed areas
Most cases do not have a recognizable cause
Recognized etiologies
Post operative
Medication side effects
Long distance runners
Cocaine
Dehydration
Elderly
Presentation
Abdominal pain
Diarrhea
Lower GI bleed
Diagnosis
CT
Colonoscopy
Angio (for R sided involvement)
Treatment
Bowel Rest
IVF
Abx
Indications for surgery in colonic ischemia
Acute indications
- Peritoneal signs
- Massive bleeding
- Universal fulminant colitis with or without toxic megacolon
Subacute indications
- Failure of an acute segmental ischemic colitis to respond within 2-3 weeks with continued symptoms or a protein-losing colopathy
- Apparent healing but with recurrent bouts of sepsis
Chronic indications
- Symptomatic colonic stricture
- Symptomatic segmental ischemic colitis