In patients where there has been a clear intra-abdominal catastrophe (which is often the case with acute mesenteric ischemic), extensive laboratory and radiographic testing unnecessarily delays bowel revascularization, leading to increased bowel loss and higher rates of patient mortality. Resuscitation must proceed expeditiously as the patient is prepared for emergency laparotomy. Surgeons may reasonably immediately move to operative exploration in patients presenting with classical history and physical findings with minimal laboratory testing and no preoperative imaging. Terse preoperative frank yet sensitive discussions with the patient and family can reinforce the life-threatening nature of acute mesenteric ischemia, and this may also serve as a time to introduce the concept of “inoperable” circumstances such as massive bowel infarction. Determination of ischemic versus infarcted bowel remains difficult with currently available clinical and imaging tools, so exploration is most often necessary for assessment. With less dramatic clinical presentations, symptomatic acute mesenteric embolus or thrombosis diagnosed by way of the algorithms outlined above also standardly warrants emergency exploration and bowel revascularization.

The surgeon’s focus on timely clinical diagnosis, immediate laparotomy, and urgent bowel reperfusion via surgical interventions builds from the report of Klass from almost 60 years ago. Patients suffering acute SMA obstruction require multiple parallel interventions in preparation for the operating room. Yet none of these should stand as a rate-limiting step toward skin incision, since these patients can deteriorate rapidly and every minute of delay jeopardizes outcome. Upon diagnosis of acute mesenteric ischemia, the patient is systemically heparinized to minimize clot propagation. Activated clotting times throughout the operative period ensures adequate systemic anticoagulation. Empiric broad spectrum antibiotics are commonly employed since many of these patients have early sepsis, and they additionally serve as some surgical wound prophylaxis (third-generation cephalosporin such as ceftriaxone and metronidazole and in the penicillin-allergic patient a fluoroquinolone and metronidazole). Patients who are health care experienced (recent hospital/nursing home stay, regular visits to hemodialysis centers, etc.) should have their coverage tailored based on local antibiograms. As many of these patients are hypovolemic and have electrolyte abnormalities, fluid volume resuscitation is almost always indicated. Fluid infusion should be targeted to clinical endpoints such as urinary output, skin turgor, and capillary refill; electrolyte abnormalities (especially hypokalemia, hypomagnesemia, and hypophosphatemia) should be corrected as resuscitation proceeds. There is ongoing debate over the optimal type of fluid to use for resuscitation. While the evidence does not support one type of fluid over another, it is best to keep in mind that no matter what type of fluid is used, the clinical response to resuscitation should be closely monitored to prevent both underresuscitation (which can lead to organ failure) and overresuscitation (which can stress the heart and lungs and precipitate myocardial ischemia). All available personnel should work in parallel to place hemodynamic monitors such as arterial lines, secure venous access, a Foley catheter, and a nasogastric tube. Simultaneously, the status of lower extremity pulses is again documented since this patient subset often holds risk factors for lower extremity occlusive disease and may have embolized to the lower extremity arteries.