Seldinger technique is a minimally invasive technique in which the practitioner accesses the target vessel with a small bore needle, then dilates to the size required for the catheter. Contrarily, modified Seldinger technique(guiding sheath-over-the-needle technique) use needle that is covered with guiding sheath.

Both technique is widely used in central venous catheterization, however, few researches have been investigated to compare success rate or complications of both methods.

The major complications of central venous catheterization through subclavian vein, are unintended arterial puncture, pneumothorax, hemothorax, malposition of catheter etc,. We assume that using modified Seldinger technique (MST), guiding sheath is easily slid over the needle, providing stable route into the vessel lumen relatively.

We aimed to compare the Seldinger technique and modified Seldinger technique(MST) on success rate and complications during subclavian central venous catheterization in this prospective, randomized , controlled trials.

Inclusion Criteria:

• patient scheduled for surgery under genearl anesthesia and subclavian vein central catheterization

Exclusion Criteria:

• Patient who does not agree to the study
• Inflammation or infection on catheterization site
• Contralateral diaphragmatic dysfunction
• Anatomic anomalies of subclavian artery or vein/clavicle
• Previous lung surgical history
• Patient who has ventriculoperitoneal shunt or chemoport on same side
• Patient who has pneumo/hemothorax or lung parenchymal disease