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Difficulty: HardCardiothoracic and Vascular Surgery

A 71-year-old male is assessed in the intensive care unit on postoperative day 3 following an emergent open repair of a ruptured abdominal aortic aneurysm. His past medical history includes chronic obstructive pulmonary disease, ischemic cardiomyopathy, and hypertension. Over the past several hours, he has developed worsening generalized abdominal pain and just passed a large amount of dark, bloody stool. He also complains of new-onset shortness of breath. Vital signs are temperature 38.6°C (101.5°F), blood pressure 82/50 mm Hg, pulse 130/min, and respirations 26/min. Pulse oximetry is 92% on a nasal cannula. Physical examination reveals a markedly distended, rigid abdomen with diffuse tenderness and involuntary guarding. Bowel sounds are absent. Lung auscultation demonstrates scattered expiratory wheezes. Laboratory results are notable for a leukocyte count of 22,000/mm³ and a serum lactate of 6.8 mmol/L. Despite an initial bolus of intravenous crystalloid, his blood pressure remains 84/52 mm Hg. Which of the following is the most appropriate next step in management?

  1. Emergent exploratory laparotomyAnswer
  2. B
    Abdominal and pelvic computed tomography angiography
  3. C
    Nasogastric tube decompression and serial examinations
  4. D
    Intravenous furosemide and noninvasive positive pressure ventilation
  5. E
    Urinalysis, urine culture, and empiric intravenous ceftriaxone

Answer

Emergent exploratory laparotomy
The correct answer is emergent exploratory laparotomy. This patient is presenting with classic signs of acute colonic ischemia (severe abdominal pain, bloody diarrhea) following an open abdominal aortic aneurysm (AAA) repair. During open AAA repair, the inferior mesenteric artery (IMA) is often sacrificed. While collateral circulation from the superior mesenteric artery (via the marginal artery of Drummond) is usually sufficient, patients with poor collaterals or periods of perioperative hypotension are at high risk for colonic ischemia, particularly at the splenic flexure (Griffith's point) and rectosigmoid junction (Sudeck's point). This patient has developed full-thickness bowel necrosis leading to perforation, evident by his rigid abdomen with involuntary guarding (peritonitis) and septic shock (hypotension despite fluid resuscitation, fever, marked leukocytosis, and severe lactic acidosis). The presence of peritonitis in a hemodynamically unstable patient is an absolute indication for immediate surgical exploration to resect the dead bowel.

Step-by-Step Solution

1
Analyze the patient's symptoms and surgical history
The patient is status post open abdominal aortic aneurysm (AAA) repair and presents with bloody diarrhea and severe abdominal pain.
During open AAA repair, the inferior mesenteric artery (IMA) is often ligated, placing the patient at high risk for acute colonic ischemia, particularly in watershed areas like the splenic flexure.
2
Evaluate the patient's hemodynamic status and physical examination findings
The patient is in distributive (septic) shock (hypotension unresponsive to fluids, tachycardia, fever, high lactate) and has a rigid, distended abdomen with involuntary guarding.
These findings indicate that the colonic ischemia has progressed to full-thickness bowel infarction and perforation, leading to severe peritonitis.
3
Determine the appropriate intervention based on stability and examination
The next step is emergent exploratory laparotomy.
Hemodynamically unstable patients with peritonitis must bypass diagnostic imaging and be taken immediately to the operating room for life-saving resection of the necrotic bowel.

Key Concept

Management of acute colonic ischemia following abdominal aortic aneurysm repair
Estimated Time:1m 30s
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Topics

Cardiothoracic and Vascular Surgery

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