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1042 PART 9: Gastrointestinal Disorders

electrolyte disturbances such as hypokalemia, hypomagnesemia, and
hypophosphatemia should be corrected. Broad-spectrum antibiotics
(eg, second-generation penicillin or third-generation cephalosporin,
along with anaerobic coverage) should be administered intravenously.
Analgesia should not be withheld in the conscious patient. Systemic
heparinization is advocated once the diagnosis is suspected, unless there
are absolute contraindications. The goal is a partial thromboplastin time
(PTT) of greater than 2 times control.
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IMA origin DIAGNOSTIC APPROACH
Where there is diagnostic doubt in a patient with suspected mesenteric
ischemia, CT angiography is recommended as the initial diagnostic
test. Patients should receive fluid resuscitation prior to contrast admin-
istration to prevent renal contrast toxicity. Scan review with an expert
radiologist will determine the next steps. Alternately diagnostic mes-
enteric angiography is advocated. Modern catheters and techniques
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reduce the risks of bleeding, dissection, and embolization. In a well-
resuscitated patient, small-volume nonionic contrast and digital sub-
traction angiography (DSA) limit the risk of nephrotoxicity and contrast
reaction. An initial flush aortogram may define the origins of the major
vessels and outline possible collateral pathways. Selective mesenteric
artery catheterization allows for thorough assessment of individual arte-
rial territories and opens up therapeutic options. 39
■
FIGURE 109-4. Angiographic image of elective injection of the IMA with severe origin THERAPEUTIC ALTERNATIVES
stenosis. Therapy will be dictated by the CT or angiographic findings. If an
embolus is identified, then operative SMA embolectomy should be
performed. If SMA stenosis with thrombosis is present, then two alter-
natives are possible. Conventional mesenteric angioplasty and stenting
combined with possible thrombolysis or laparotomy with SMA throm-
bectomy and retrograde SMA angioplasty (ROMS) are possible. The
latter has the advantages of allowing direct bowel inspection and arterial
bypass if angioplasty fails to recanalize the arterial inflow to the bowel.
Intraoperative angioplasty may not be available at all centers and this
may influence the location of where the angioplasty occurs.
For NOMI, catheter-based therapy is the treatment of choice in
the absence of definitive signs of intestinal infarction. Papaverine
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(30-60 mg/h) is infused selectively into the SMA for a period of 24 hours.
Repeat flush angiography should confirm partial or complete resolution
of spasm 30 minutes after beginning the infusion and prior to the patient’s
return to the ICU. Papaverine is a potent phosphodiesterase inhibitor,
leading to increased intracellular cAMP and vasodilation. Because of
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extensive hepatic first-pass metabolism, systemic effects such as hypoten-
sion generally are modest. Alternatively, prostaglandin administration
of an initial bolus of 20 µg and subsequent infusion of 2.5 to 5 µg/h for
a maximum of 3 days according to Bruch et al may be effective as well.
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Angiographic imaging may be performed after initial bolus administra-
FIGURE 109-5. CT Angiogram showing embolus in the SMA. tion and if no improvement is observed following a 24-h interval. Failure
of therapy may be signaled by cardiovascular instability, progression of
clinical symptoms or signs, and catheter displacement or blockage.
vessels, and slow flow with increased reflux of contrast material into Occlusive mesenteric ischemia traditionally requires surgery. However,
the aorta during selective injection. An increase in vessel caliber after increasing numbers of interventional radiologists are exploring the use of
transcatheter papaverine injection may clinch the diagnosis. Mesenteric catheter-based therapies as long as there is no frank intestinal infarction.
venous thrombosis is seen on the later phase of angiography with con- A number of techniques are available for recanalization, including suc-
trast stasis and lack of portal venous phase filling. tion clot retrieval, thrombolysis, angioplasty, and stenting. All these
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techniques remain investigational and should be conducted only in col-
MANAGEMENT laboration with an appropriately trained surgeon and an interventional
Initial management includes resuscitation from hypoperfusion or elec- radiologist and with appropriate monitoring and reassessment of the
44
trolyte abnormalities while planning further definitive steps toward patient. Even when a decision is made to proceed to surgery, continued
diagnosis and treatment. Simple airway management with supplemental infusion of papaverine or heparin into the occluded vessel may improve
oxygen by mask, titrated to achieve oxygen saturation above 95%, will distal circulation and prevent clot propagation pending definitive surgery.
typically should be intubated electively, bearing in mind the risk of ■ MINIMALLY INVASIVE SURGERY
suffice in patients who are breathing spontaneously. Obtunded patients
aspiration owing to gastroparesis and intestinal ileus. A wide-bore In the setting of high suspicion of acute mesenteric ischemia, some have
nasogastric tube should be placed for intestinal decompression. Acute advocated laparoscopic assessment of the abdominal contents and
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