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Difficulty: MediumCardiothoracic and Vascular Surgery

An 80-year-old female resident of a nursing facility is brought to the emergency department due to a sudden onset of generalized, severe abdominal pain. She has a history of persistent atrial fibrillation and is not taking anticoagulants due to a prior gastrointestinal bleed. On examination, her blood pressure is 75/45 mmHg75/45 \text{ mmHg}, heart rate is 125/min125/\text{min} and irregular, and respiratory rate is 24/min24/\text{min}. Her abdomen is rigid with diffuse involuntary guarding and rebound tenderness. Arterial blood gas shows a pH of 7.157.15, pCO2\text{pCO}_2 of 30 mmHg30 \text{ mmHg}, and calculated bicarbonate of 10 mEq/L10 \text{ mEq/L}. Serum lactate is 8.5 mmol/L8.5 \text{ mmol/L}. Which of the following is the most appropriate next step in the management of this patient?

  1. Emergent exploratory laparotomyAnswer
  2. B
    Computed tomography angiography of the abdomen and pelvis
  3. C
    Placement of a nasogastric tube, intravenous fluids, and serial abdominal examinations
  4. D
    Withholding surgical intervention until the legally appointed healthcare proxy arrives
  5. E
    Administration of intravenous furosemide and noninvasive positive pressure ventilation

Answer

Emergent exploratory laparotomy
The correct answer is emergent exploratory laparotomy. This patient has classic risk factors for a superior mesenteric artery (SMA) embolus (atrial fibrillation without anticoagulation). The severe abdominal pain, profound lactic acidosis, and shock are highly concerning for acute mesenteric ischemia. Crucially, her rigid abdomen and involuntary guarding indicate peritonitis resulting from transmural bowel infarction. In any hemodynamically unstable patient with peritonitis, the most appropriate next step is emergent operative exploration. This allows for both definitive diagnosis and immediate treatment, which typically involves resection of frankly necrotic bowel segments and restoration of blood flow (e.g., via embolectomy or bypass) to ischemic but viable segments.

Step-by-Step Solution

1
Analyze the patient's risk factors and clinical presentation.
The patient has atrial fibrillation without anticoagulation, placing her at high risk for thromboembolism. The sudden, severe abdominal pain and elevated lactate point toward acute mesenteric ischemia.
Identifying the underlying pathology (vascular compromise of the intestine) is crucial for guiding management.
2
Evaluate the physical examination and vital signs.
The presence of a rigid abdomen with rebound tenderness indicates peritonitis. Hypotension (75/45 mmHg75/45 \text{ mmHg}) and tachycardia indicate hemodynamic instability and shock.
Peritonitis and hemodynamic instability in the setting of suspected bowel ischemia signify transmural bowel infarction and impending cardiovascular collapse.
3
Determine the most appropriate immediate intervention.
The patient requires an emergent exploratory laparotomy.
While CT angiography is the diagnostic modality of choice in stable patients with suspected mesenteric ischemia, hemodynamically unstable patients with peritonitis must be taken directly to the operating room for resection of necrotic bowel and potential revascularization.

Key Concept

Hemodynamically unstable patients presenting with an acute surgical abdomen (peritonitis) and suspected acute mesenteric ischemia require emergent exploratory laparotomy without delaying for further imaging.
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Topics

Cardiothoracic and Vascular Surgery

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