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Difficulty: MediumCardiothoracic and Vascular Surgery

An emergency medical services team rushes a 71-year-old woman to the emergency department after she experienced an abrupt onset of agonizing, diffuse abdominal pain 2 hours ago. She has a medical history of paroxysmal atrial fibrillation (for which she has not been taking her prescribed oral anticoagulant), type 2 diabetes mellitus, and chronic bronchitis. Her temperature is 37.4°C (99.3°F), blood pressure is 82/50 mmHg, pulse is 134/min and irregularly irregular, and respirations are 28/min. Physical examination reveals a diaphoretic, lethargic patient writhing in pain. Lung auscultation demonstrates prolonged expiration with scattered end-expiratory wheezes. The abdomen is markedly distended and extremely tender to light palpation in all quadrants, with board-like rigidity and involuntary guarding. Bowel sounds are absent.

Arterial blood gas analysis on room air reveals:
pH: 7.18
pCO2pCO_2: 30 mmHg
pO2pO_2: 65 mmHg
HCO3−HCO_3^-: 11 mEq/L

Serum lactate is 9.2 mmol/L.

Which of the following is the most appropriate next step in the management of this patient?

  1. Immediate transfer to the operating room for abdominal explorationAnswer
  2. B
    CT angiography of the mesenteric circulation
  3. C
    Placement of a nasogastric tube and serial clinical observations
  4. D
    Intravenous administration of corticosteroids and inhaled bronchodilators
  5. E
    Administration of intravenous sodium bicarbonate therapy

Answer

Immediate transfer to the operating room for abdominal exploration
The patient's presentation of abrupt, severe abdominal pain in the setting of unanticoagulated atrial fibrillation is classic for acute mesenteric ischemia caused by an arterial embolus. The development of hemodynamic instability (blood pressure 82/50 mmHg), profound lactic acidosis (9.2 mmol/L), and frank peritonitis (board-like rigidity and involuntary guarding) indicates that the ischemia has advanced to transmural bowel infarction. In any patient presenting with an acute surgical abdomen and shock, the correct next step is emergent exploratory laparotomy to remove necrotic bowel and restore perfusion.

Step-by-Step Solution

1
Identify the primary pathology based on the clinical presentation.
The combination of sudden severe abdominal pain and unanticoagulated atrial fibrillation points to an acute superior mesenteric artery embolus.
Atrial fibrillation predisposes to mural thrombus formation, which can embolize to the mesenteric vessels.
2
Assess the patient's hemodynamic and abdominal status.
The patient exhibits hypotension, tachycardia, a rigid abdomen with involuntary guarding (peritonitis), and profound lactic acidosis.
These findings indicate that the ischemia has progressed to transmural bowel infarction and septic/hypovolemic shock.
3
Determine the most appropriate management for the current clinical state.
The patient must be taken immediately to the operating room for an exploratory laparotomy.
Hemodynamically unstable patients with an acute surgical abdomen (peritonitis) require emergent surgical exploration to resect necrotic tissue; advanced diagnostic imaging will critically delay life-saving treatment.

Key Concept

Management of complicated acute mesenteric ischemia
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Topics

Cardiothoracic and Vascular Surgery

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