Immediate complications are of mechanical nature and related to operator technique and experience. It is important to know, recognize, and manage the immediate complications as they can become rapidly life-threatening in nature. Risk factors for immediate complications include operator inexperience, number of needle passes, and larger catheter size. Mechanical complications include puncture of adjacent artery, hematoma, air embolism, arrhythmia, pneumothorax pericardial tamponade, catheter/wire embolus, arteriovenous fistula, vessel obstruction, vessel perforation, pseudoaneurysm formation, catheter malposition, and catheter knotting.14,15,16,17,18,19 Subclavian vein catheterization has been associated with the highest risk of pneumothorax.