ICU · GI and nutrition

Acute mesenteric ischaemia: embolic, thrombotic, venous, and non-occlusive

Also known as Mesenteric ischaemia · Bowel ischaemia · Intestinal ischaemia · Mesenteric embolus · Non-occlusive mesenteric ischaemia · NOMI

Acute mesenteric ischaemia = sudden reduction in intestinal blood flow - bowel necrosis (if untreated). FOUR TYPES: (1) ARTERIAL EMBOLUS (50%) — AF/source - SMA embolus (sudden, proximal, no collaterals). (2) ARTERIAL THROMBOSIS (25%) — atherosclerotic SMA stenosis - acute thrombosis (on background of chronic 'mesenteric angina'). (3) NON-OCCLUSIVE MESENTERIC ISCHAEMIA (NOMI — 20%) — low-flow state (shock, vasopressors, dialysis) - diffuse vasoconstriction - ischaemia (no large vessel occlusion). (4) MESENTERIC VENOUS THROMBOSIS (5%) — portal/mesenteric vein clot (hypercoagulable, infection, inflammation). CLINICAL: severe abdominal pain OUT OF PROPORTION to examination (early — bowel still viable), then peritonitis (late — necrosis). LACTATE elevated (ischaemia). CT angiography (gold standard — occlusion type, location, bowel viability). MANAGEMENT: EMERGENCY surgery (revascularisation + resect necrotic bowel) for arterial occlusion; ANTICOAGULATION for venous; PAPAVARINE infusion + treat low-flow for NOMI. MORTALITY: 50-80% (delayed diagnosis is the killer).