Non-Occlusive Mesenteric Ischemia (NOMI) Diagnosis and Management

Pathophysiology and Epidemiology

Non-occlusive mesenteric ischemia (NOMI) is acute intestinal ischemia caused by superior mesenteric artery vasoconstriction and reduced splanchnic blood flow in the absence of a physical blockage in the mesenteric vessels, typically affecting both the small bowel and proximal colon 1
NOMI accounts for 20-30% of all acute mesenteric ischemia cases, with recent data showing an increase to approximately 25% due to improved intensive care allowing more critically ill patients to survive longer 1

NOMI occurs almost exclusively in critically ill patients with specific risk factors, including cardiac failure, septic shock requiring vasopressor support, and severe hypovolemia 1, 2
The key diagnostic challenge is that NOMI often presents with subtle or absent clinical signs in sedated ICU patients, with critical warning signs including unexplained abdominal distension, gastrointestinal bleeding, new onset organ failure, and nutrition intolerance in critically ill patients 3

CTA remains the primary diagnostic modality, showing bowel ischemia and free fluid in the presence of patent mesenteric vessels, distinguishing it from embolic or thrombotic causes 3
Selective mesenteric angiography is the gold standard for definitive diagnosis, demonstrating characteristic findings of peripheral vasoconstriction without proximal occlusion, with key distinguishing features including no embolus, no thrombosis at the SMA origin, and no venous thrombosis 1, 3