Cardiology Clinical Case / MCQS / Uworld for Usmle step 2 / case 7

 

Cardiology Clinical Case  / MCQS / Uworld for Usmle step 2 / case7 with answer and explanation and references and Educational objective

A 55-year-old male is admitted to the ICU after being involved in a motor vehicle accident. He requires exploratory laparotomy for suspected bowel perforation. Two days after the surgery he remains hypotensive and requires both aggressive intravenous fluids and vasopressors to maintain his blood pressure. On physical examination, you note the fingertip changes pictured below:

All four extremities feel cold to touch. Which of the following is most likely responsible?

A Septic emboli . B. Raynaud's phenomenon . C. Norepinephrine-induced vasospasm . D. Cholesterol emboli . E. Superior vena cava syndrome .

 

Answer : C

Explanation:

This patient's cool, dusky fingertips are the result of norepinephrine-induced vasospasm. Norepinephrine has alpha-1 agonist properties which cause vasoconstriction; this property is useful when trying to increase the blood pressure of hypotensive patients. However, in some patients with decreased blood flow, vasoconstriction can result in ischemia and necrosis of the distal fingers and toes.. A similar phenomenon can occur in the intestines (resulting in mesenteric ischemia) or kidney (causing renal failure).

 

(Choice A) Endocarditis can spread septic emboli throughout the body, but would not be expected to affect all fingers.

 

(Choice B) Raynaud's phenomenon is a cause of finger ischemia that typically progresses from pallor to cyanosis to erythema. It can be accompanied by pain and is usually due to cold exposure or stress. The duskiness of the fingers pictured above, however, is more suggestive of ischemia.

 

(Choice D) Cholesterol emboli can occur in patients with atherosclerosis and can affect the distal portions of the digits, thus its occasional name "blue toe syndrome." However, symmetrical involvement of all digits would be unusual.

 

(Choice E) Superior vena cava syndrome occurs in patients with lung cancer, thrombi, or fibrosing mediastinitis and can cause upper extremity edema. However, arterial flow is preserved and so ischemia does not occur.

Educational objective: 

Pressors such as norepinephrine can cause ischemia of the distal fingers and toes secondary to vasospasm. The diagnosis is suggested by symmetric duskiness and coolness of all fingertips.

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