A 74-year-old man is evaluated in the hospital for severe, sudden-onset abdominal pain. He was admitted 3 days ago for shortness of breath and lower extremity edema, for which he has been receiving intravenous furosemide. His medical history is significant for ischemic cardiomyopathy, persistent atrial fibrillation, and chronic obstructive pulmonary disease (COPD). On examination today, he appears in acute distress. His temperature is 37.8°C (100°F), blood pressure is 105/65 mm Hg, pulse is 118/min and irregularly irregular, and respirations are 24/min. The abdomen is moderately distended but remarkably soft and non-tender to deep palpation; bowel sounds are hypoactive.
Arterial blood gas analysis on room air shows:
| Parameter | Value | Reference Range |
|---|---|---|
| pH | 7.27 | 7.35-7.45 |
| pCO2 | 30 mm Hg | 35-45 mm Hg |
| pO2 | 85 mm Hg | 75-105 mm Hg |
Serum chemistry shows:
| Parameter | Value | Reference Range |
|---|---|---|
| Sodium | 138 mEq/L | 136-145 mEq/L |
| Potassium | 4.8 mEq/L | 3.5-5.0 mEq/L |
| Chloride | 102 mEq/L | 95-105 mEq/L |
| Bicarbonate | 14 mEq/L | 22-28 mEq/L |
| Blood urea nitrogen | 35 mg/dL | 7-18 mg/dL |
| Creatinine | 1.6 mg/dL | 0.6-1.2 mg/dL |
| Lactate | 6.2 mmol/L | 0.5-1.0 mmol/L |
Which of the following is the most appropriate next step in management?
- Computed tomography angiography of the abdomenAnswer
- BInsert a nasogastric tube and obtain an upright abdominal radiograph
- CIncrease the dose of intravenous furosemide and obtain a chest radiograph
- DInitiate non-invasive positive pressure ventilation
- EAdminister intravenous piperacillin-tazobactam and monitor closely in the intensive care unit
Answer
Computed tomography angiography of the abdomen
The patient is presenting with the classic triad of acute mesenteric ischemia (AMI): sudden onset of severe abdominal pain out of proportion to physical examination findings, risk factors for thromboembolism (persistent atrial fibrillation, ischemic cardiomyopathy), and metabolic acidosis with elevated lactate. Embolization to the superior mesenteric artery (SMA) is the most common cause. The pain is severe, but because the visceral peritoneum lacks somatic innervation, the abdomen remains soft and non-tender early in the disease course. The elevated lactate and high anion gap metabolic acidosis indicate active tissue ischemia. Since the patient does not yet exhibit frank peritonitis (which would mandate emergent exploratory laparotomy), the most appropriate next step is urgent computed tomography (CT) angiography of the abdomen and pelvis. This highly sensitive and specific test allows for rapid visualization of the mesenteric vasculature to plan for emergent revascularization.
Step-by-Step Solution
Key Concept
Diagnosis and management of acute mesenteric ischemia
Estimated Time:1m 30s