## **Core Concept**
The management of pulmonary emboli involves various treatment strategies, including anticoagulation, thrombolysis, and embolectomy. Thrombolytic therapy, such as with alteplase (a tissue plasminogen activator), is used in specific cases of pulmonary embolism (PE) to dissolve the clot. Alteplase works by converting plasminogen into plasmin, which then breaks down fibrin clots.

## **Why the Correct Answer is Right**
The correct duration for the infusion of alteplase (tPA) in the management of pulmonary emboli is **2 hours**. Alteplase is administered intravenously for a short duration, typically 2 hours, to minimize the risk of bleeding complications while maximizing the chance of clot lysis. This duration allows for the therapeutic effect of alteplase on the clot without excessively prolonging the risk of systemic bleeding.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 30 minutes - This duration is too short for alteplase infusion in the context of pulmonary emboli management. A shorter duration might not effectively lyse the clot.
- **Option B:** 24 hours - This is excessively long and would significantly increase the risk of bleeding complications without providing additional benefit over the standard 2-hour infusion.
- **Option D:** 48 hours - Similar to option B, this duration is far too long and would not be used for alteplase infusion in pulmonary embolism due to the high risk of severe bleeding.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that thrombolytic therapy with alteplase is typically reserved for patients with pulmonary embolism who are hemodynamically unstable or have evidence of right heart strain, as it carries a significant risk of bleeding. The standard infusion time of **2 hours** is critical for balancing efficacy and safety.

## **Correct Answer:** . **2 hours**