Acute Mesenteric Ischemia: Epidemiology, Etiology, Diagnosis and Treatment

Acute mesenteric ischemia (AMI) is a condition where there is a reduction in the blood flow to the intestine leading to inadequate perfusion. The issue of AMI may be caused as a reflection of generalized poor perfusion, or it may also be a result of local pathology. The incidence of AMI in acute surgical admissions is rare but the mortality rate is high and is more than 50%. 

Epidemiology

Considering the epidemiology of the disease, the rate of incidence of AMI is found to be increasing over the last few decades which contributes to the requirement of advancing medical technology, developing new therapies that can help the critically ill patients developing AMI.

Etiology

AMI can be caused due to a wide range of reasons including occlusive arterial disease, atherosclerotic narrowing of the mesenteric bed, systemic embolism, vasculitis, hypercoagulable states, splanchnic vasoconstriction, hypotension, low cardiac output and others.

Risk Factors

The major risk factors for AMI includes having an age ≥50 years, suffering from atherosclerotic heart disease, having congestive heart failure, recent myocardial infarction or valvular heart diseases. 

Evaluation

In order to evaluate, it is important to check the patient’s history & perform a general examination. The major complaint noted in such cases is having severe abdominal pain. Other than this, the presence of peritoneal signs (e.g., rebound tenderness), intestinal infarction, abdominal distention, emesis and other signs of intestinal obstruction may be 
observed in patients. Laboratory Findings may indicate leukocytosis in 75% of patients, metabolic acidosis, elevated amylase, creatine kinase (CK) (6–12 h after infarction has 
occurred), lactate and phosphate. Further, radiologic evaluation like performing abdominal X-rays need to be done as soon as the patient has been adequately resuscitated as it can help in excluding other causes of abdominal pain (mechanical obstruction, perforation). Seventy percent of the patients tend to show at least either of the issues of ileus, ascites, small bowel dilation, separation of small bowel loops, thickening of valvulae conniventes, thumb printing. Computed tomography (CT) is considered in the case of mesenteric vein thrombosis as it can show focal or segmental bowel wall thickening or intestinal pneumatosis. Moreover, arteriography can help in adequate diagnosis and it also helps in providing a “road map” to the surgeon.

Treatment:

Adequate hydration is the major step of treating AMI. It may also be required to perform an invasive hemodynamic monitoring in order to maximize cardiac output, oxygen delivery, and volume status in patients. Further, if patients have embolic or thrombotic occlusion, they need to have an urgent laparotomy for possible resection. Prescribing heparin and broad-spectrum antibiotics are indicated before surgery. In the cases of nonocclusive AMI, intra-arterial infusions of vasodilators (e.g., papaverine 30–60 mg/h) may be required by some patients.

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