Certified Surgical Technologist (CST) Practice Exam

Which agent is used to flush an artery to prevent clotting?

1. Thrombin

2. Protamine sulfate

3. Heparin

4. Ringer's lactate

The correct answer is: Heparin

Heparin is the agent used to flush an artery to prevent clotting because it is a powerful anticoagulant. It works by inhibiting thrombin and other factors in the coagulation cascade, thereby preventing the conversion of fibrinogen to fibrin and the formation of a clot. In surgical procedures, heparin is often administered to maintain patency in vessels, especially during procedures involving vascular surgery or interventions where blood flow needs to be maintained without clotting. The other choices do not serve the purpose of flushing arteries to prevent clotting effectively: Thrombin is primarily used to promote clotting and may be used in situations where hemostasis is required, making it unsuitable for a scenario where clotting needs to be prevented. Protamine sulfate is an antagonist to heparin, used primarily to reverse the effects of heparin after surgery or procedures where heparin was administered. Therefore, it would not be suitable for flushing to prevent clotting. Ringer's lactate is a type of intravenous fluid that helps maintain hydration and electrolyte balance, but it does not possess any anticoagulation properties and therefore cannot be used for the purpose of preventing clotting in arteries. Thus, heparin is the appropriate agent for this