Gastrointestinal System >
Bowel Ischaemia

“Decreased blood flow to the gastrointestinal tract”

  • Classifications:
    • Acute Mesenteric Ischaemia (AMI)
    • Chronic Mesenteric Ischaemia (CMI)
    • Colonic Ischaemia (CI)
Risk Factors
  • Old age
  • Smoking
  • Hypercoagulable states
  • AF
  • DM
  • History of cardiac disease
  • Peripheral arterial disease
Aetiology
  • Commonly caused by:
    • Superior mesenteric artery thrombosis (35%) or embolism (35%)
    • Mesenteric vein thrombosis (5%)
    • Non-occlusive disease (20%) in hypovolaemic/ cardiogenic shock.
  • Other rare causes include: trauma, vasculitis, radiotherapy or strangulation of vessels
Pathophysiology
  • AMI:
    • A sudden interruption of blood flow
    • Intestinal hypoxia
    • Haemorrhagic infarction and necrosis
    • Disruption of mucosal barrier and perforation
    • Sepsis
  • CMI:
    • Built-up of atherosclerotic plaque
    • Inadequate blood supply to the bowel
    • Post-prandial mismatch between splanchnic blood flow and intestinal metabolic demand causing pain
Clinical Presentation
  • AMI:
    • Abdominal pain that is out of proportion to clinical findings
    • N&V
    • Diarrhoea
    • Gangrenous bowel (rectal blooding and signs of sepsis)
    • AF/ heart murmurs as signs of potential embolic sources
  • CMI:
    • Recurrent dull postprandial pain,
    • Weight loss due to reduced calorie intake and malabsorption
    • Loose bowels
    • N&V
    • Cachexia
    • Generalised abdominal tenderness and abdominal bruits.
  • CI:
    • Lower left-sided abdominal pain
    • Bloody diarrhoea
Investigations
  • Bloods:
    • ABG – ­lactate, metabolic acidosis
    • FBC – Hb, ­WCC)
    • U&Es
    • Clotting
    • Amylase
    • LFTs
    • Creatine kinase
  • Imaging:
    • CT angiography – distended intestinal loops, wall thickening, oedematous bowel
    • Contract enhance MR angiography
  • Special:
    • Gold Standard – Lower GI endoscopy
Management
  • AMI:
    • A surgical emergency requiring urgent resuscitation
      • IV fluids
      • Catheter inserted
      • Antibiotics (e.g piperacillin/tazobactam)
      • Usually, LMWH/heparin is required.
    • In surgery dead bowel must be removed, attempt revascularisation on potentially viable bowel.
  • CMI:
    • Consider surgery
    • Percutaneous transluminal angioplasty and stent insertion
  • CI:
    • Fluid replacement
    • Antibiotics
    • Gangrenous ischaemic colitis requires resuscitation, resection of bowel and stoma formation
Complications
  • The main life-threatening complications secondary to acute mesenteric ischaemia are:
    • Septic peritonitis
    • Progression of a SIRS → multi-organ failure mediated by the bacterial translocation across the dying gut wall

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