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Difficulty: MediumRheumatology and Immunology

A 45-year-old woman with a history of diffuse cutaneous systemic sclerosis is evaluated in the hospital for acute-onset shortness of breath and a severe headache. She is currently on postoperative day 3 following an uncomplicated laparoscopic cholecystectomy. Her temperature is 37.8°C (100.0°F), blood pressure is 215/115 mm Hg, pulse is 108/min, and respirations are 24/min. Physical examination reveals taut, thickened skin over her face and fingers. Lung auscultation reveals bilateral basilar crackles.

Laboratory studies show the following:
TestResultReference Range
Hemoglobin9.0 g/dL (baseline 11.5 g/dL)12.0-16.0 g/dL
Platelets85,000/mm³150,000-400,000/mm³
Serum creatinine3.1 mg/dL (baseline 0.9 mg/dL)0.6-1.2 mg/dL

A peripheral blood smear demonstrates numerous schistocytes.

Arterial blood gas on room air:
MeasurementResultReference Range
pH7.317.35-7.45
pCO₂29 mm Hg35-45 mm Hg
pO₂68 mm Hg80-100 mm Hg
HCO₃⁻14 mEq/L22-28 mEq/L

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

  1. Administer an oral angiotensin-converting enzyme inhibitorAnswer
  2. B
    Obtain blood cultures and initiate empiric intravenous broad-spectrum antibiotics
  3. C
    Administer intravenous sodium bicarbonate to correct an uncompensated respiratory acidosis
  4. D
    Administer nebulized bronchodilators and systemic corticosteroids for an acute obstructive airway exacerbation
  5. E
    Initiate disciplinary action against the surgical team for causing a preventable perioperative complication

Answer

Administer an oral angiotensin-converting enzyme inhibitor
The correct answer identifies the need for immediate administration of an ACE inhibitor. This patient is presenting with scleroderma renal crisis (SRC), a life-threatening complication of diffuse cutaneous systemic sclerosis. It is characterized by the sudden onset of severe hypertension, acute kidney injury, and microangiopathic hemolytic anemia (evidenced by schistocytes and thrombocytopenia). The pathophysiology involves vascular endothelial injury in the kidneys leading to massive renin release. ACE inhibitors (e.g., captopril) are the treatment of choice because they directly counteract this renin-angiotensin-aldosterone system (RAAS) hyperactivation. They must be initiated promptly, even though they can transiently worsen the serum creatinine.

Step-by-Step Solution

1
Analyze the clinical presentation and history.
The patient has systemic sclerosis and presents with new-onset severe hypertension, acute kidney injury, and microangiopathic hemolytic anemia (schistocytes, thrombocytopenia).
Identifying the triad of severe hypertension, acute renal failure, and MAHA in a patient with systemic sclerosis establishes the diagnosis of scleroderma renal crisis (SRC).
2
Determine the underlying pathophysiology of the crisis.
SRC is caused by acute intimal proliferation of renal arcuate and interlobular arteries, leading to decreased renal perfusion and massive activation of the renin-angiotensin-aldosterone system (RAAS).
Understanding that RAAS hyperactivation drives the severe hypertension and progressive renal failure dictates the choice of targeted therapy.
3
Select the most appropriate pharmacological intervention.
Angiotensin-converting enzyme (ACE) inhibitors, such as captopril, are the specific treatment of choice.
ACE inhibitors directly reverse the RAAS-mediated renal vasoconstriction, preserving renal function and controlling blood pressure. They are indicated even in the presence of acute kidney injury.

Key Concept

Scleroderma renal crisis presents with acute severe hypertension, acute kidney injury, and microangiopathic hemolytic anemia in patients with systemic sclerosis. It requires emergent treatment with ACE inhibitors, even in the setting of acute kidney injury.
Estimated Time:1m 30s
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Topics

Rheumatology and Immunology

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