Non-Occlusive Mesenteric Ischemia ( NOMI )

Non-occlusive mesenteric ischemia (NOMI)

Acute mesenteric ischemia is broadly divided in to 4 Sub divisions.

Acute mesenteric arterial embolism -50%

Acute mesenteric arterial thrombosis - 25%

Non occlusive mesenteric ischemia (NOMI)-20%

Acute mesenteric venous thrombosis  -5%

“Whatever be the cause of mesenteric ischemia, gangrene of the bowel is the final common pathway ~ a mortality rate of 50-80%.”

In Non-occlusive mesenteric ischemia mesenteric arteries are patent, but the flow is low due to vaso spasm.

Risk Factors

    >50 years of age

     Myocardial infarction

     Congestive heart failure

     Aortic insufficiency

     Renal or hepatic disease

     Cardiac surgery

          Drugs- Vasopressors, Ergotamines, Cocaine, Digitalis

          Septic Shock

Pathophysiology

Tissue hypoxia can result in

Bowel wall spasm - vomiting or diarrhoea.

Mucosal sloughing -bleeding

Transmural infarction, Oedema, Congestion

Necrosis and perforation –Abdominal Distension

(8-12 hours from the onset of symptoms)

“At this stage, little abdominal tenderness is present, producing the classic intense visceral pain that is disproportionate to physical examination findings”

Clinical Presentation

 As the bowel becomes gangrenous, rectal bleeding and signs of sepsis (eg, tachycardia, tachypnea, hypotension, fever, altered mental status)

Often, these elderly patients are already in an intensive care unit (ICU) with

    Acute respiratory failure

    Hypotension from cardiogenic /septic  shock

    On vasopressive drugs or digitalis

When infarction occurs, the clinical condition of the ICU patient deteriorates with no apparent reason.

Patients may report increased pain associated with vomiting.

They may become hypotensive and tachycardic, with loose bloody stool.

Investigations

Plain radiograph- may show stripes of Air- Pneumatosis intestinalis in late stages

CT Scan Abdomen& CT Angiography-Investigation if Choice

NOMI is characterized by alternating dilation and narrowing of the intestinal branches ( “string of sausages” sign), due to spasm of the mesenteric vessels.

MR Angiogram has a sensitivity of 100% and a specificity of 91%. It is particularly effective for evaluating Mesenteric Vein Thrombosis.

Treatment

•      I/v Fluids

•      Oxygen Inhalation   maintain a saturation 96-99%

•      Vasodilators –

                Papaverine -infused through the angiography catheter

       Dose 30-60 mg/h and adjust the dose for clinical response.

       Continue this for at least 24 hours.

          If the catheter slips into the aorta, significant hypotension can occur.

•      Broad-spectrum antibiotics and pain medications
                 

 Resection of gangrenous bowel and Anastomosis.

Driven Home Messages

High degree of Suspicion is required for the diagnosis of NOMI

CT Angiogram is the Investigation of choice

Early Diagnosis and Resuscitation can decrease the morbidity and mortality.


Image Courtsey-Dr Balagopal Sir