D. Acute mesenteric ischaemia – Explanation

In acute mesenteric ischaemia, VBG typically show a high lactate. If an ABG would
have been performed, it would reveal severe metabolic acidosis with a high lactate.

Atrial fibrillation is the likely cause of the embolism that has caused the ischaemic even
in the gut. We should have a high suspicion of embolization to the superior mesenteric
artery with any patient with atrial fibrillation who complains of severe abdominal pain.

Please remember that ischaemic colitis is different from acute mesenteric ischaemia.
Mesenteric ischaemia is acute with an abrupt cessation of blood supply to the gut whilst
ischaemic colitis has a chronic presentation over hours which occurs due to a transient
disruption of blood supply to the colon.

In the Emergency Department, if mesenteric ischaemia is suspected, resuscitation with
oxygen and intravenous fluids should be commenced. Also administer intravenous
analgesia and broad spectrum intravenous antibiotics. These patients need to be
referred to the surgeons urgently.

Mesenteric ischaemia
Mesenteric ischaemia is the abrupt cessation of blood supply to a large portion of the
bowels resulting to irreversible gangrene.
Usually occurs in the middle-aged or elderly patients.

Causes

• Mesenteric arterial embolism (seen in patients with atrial fibrillation)
• Decreased mesenteric arterial blood supply (seen in patients with hypertension
  secondary to myocardial ischaemia)

Clinical features

• Severe sudden onset of abdominal pain
• Severity of pains exceeds the physical signs
• Absent bowel sounds
• Abdominal distension and tendernes

MESENTERIC ISCHAEMIA VS ISCHAEMIC COLITIS