**Question:** Commonest complication of subclavian venous puncture is

A. Pulmonary embolism
B. Air embolism
C. Bleeding
D. Infection

**Core Concept:** Subclavian venous puncture is a procedure performed to access the subclavian vein for routine or diagnostic purposes. Common complications include pulmonary embolism, air embolism, bleeding, and infection.

**Why the Correct Answer is Right:** The correct answer is B. Air embolism because it is the most common complication associated with subclavian venous puncture. Air can enter the bloodstream during the procedure, potentially reaching the heart and lungs, causing air embolism. This can lead to serious complications such as hypotension, cardiac arrhythmias, and even death if not promptly recognized and managed.

**Why Each Wrong Option is Incorrect:**

A. Pulmonary embolism (Option A) is a separate entity and not directly caused by subclavian venous puncture. It occurs when a blood clot travels from the leg veins to the lungs.

B. Air embolism (Option B) is discussed as the correct answer.

C. Bleeding (Option C) is a complication, but it is less common compared to air embolism. Bleeding may occur due to excessive pressure or improper technique during the procedure.

D. Infection (Option D) is a potential complication but is less common as sterile technique is employed during the procedure. Infection can occur due to inadequate sterilization of the puncture site.

**Clinical Pearl:** Thorough knowledge of the procedure, technique, and potential complications is essential for safe and effective subclavian venous puncture. Adequate pre-procedure preparation, sterile technique, and immediate recognition and management of complications can significantly reduce the risk of complications.