USMLE CD block 1 #34 - triplehelix

[ArchivalUser]

A 24-year-old man is brought to the emergency
department after sustaining a stab wound to the
left anterior thorax just medial to the nipple. He is
combative on arrival. His blood pressure is 70/50
mm Hg. The neck veins are distended. Breath
sounds are normal bilaterally. Which of the
following is the most appropriate next step in
management?
(A) X-ray of the chest
(B) Endotracheal intubation
© ECG
(D) Insertion of a tube into the left side of
the chest
(E) Pericardiocentesis

[ArchivalUser]

e?

[ArchivalUser]

The correct answer is E. A stab wound to the chest may perforate the myocardium, causing blood to leak into the pericardial space, resulting in pericardial tamponade. Tamponade results in increased intrapericardial pressure, which causes decreased venous return and ventricular filling (the cause of distended neck veins). Stroke volume decreases, and pulse pressure decreases. Cardiac trauma causes rapid onset of tamponade, the classic triad of symptoms being: (a) failing arterial blood pressure; (b) increased systemic vascular resistance; and © quiet heart on auscultation. This patient urgent pericardiocentesis is indicated. This procedure involves draining the pericardium so that cardiac compression is relieved. Percutaneous pericardiocenteses can be performed blindly, or can be echocardiogram-guided. Removing a small amount of fluid results in immediate hemodynamic improvement.

ari vederci

[ArchivalUser]

Here are the released answered to the USMLE CD

http://rapidshare.com/files/26158967/S2_...leased.pdf

Ari Vederci