What is the target PTT range for a patient receiving heparin after a pulmonary embolism?

• A. 46-70 seconds
• B. 20-40 seconds
• C. 10-20 seconds
• D. 70-90 seconds

Answer: (A)

The question tests understanding of how unfractionated heparin is monitored with the PTT to achieve therapeutic anticoagulation after a pulmonary embolism. Heparin prolongs clotting time, so we adjust the dose to keep the PTT within a target range that provides enough anticoagulation to prevent clot extension without causing excessive bleeding. A typical therapeutic target is about 1.5 to 2.5 times the normal PTT. Since normal PTT is roughly 25–35 seconds, the practical therapeutic window often falls around the mid to upper range of that proportional target, for many settings about 46–70 seconds. Therefore, the value of 46–70 seconds best represents a safe, therapeutic range for patients on heparin after a PE.

Lower ranges (too short) would mean insufficient anticoagulation, while much higher values (too long) increase bleeding risk. This middle range keeps the balance between preventing further clotting and avoiding bleeding.