The subclavian vein (SVC) may be preferred for central venous access if, for example, the patient has a cervical spine injury, or perhaps the line is for long-term use (e.g. dialysis, feeding) and this site may be more comfortable for the patient.
Anatomy of the SCV (click for larger images)
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The SCV is the continuation of the axillary vein and originates at the lateral border of the first rib. The SCV passes over the first rib anterior to the subclavian artery, to join with the internal jugular vein at the medial end of the clavicle. The external jugular vein joins the SCV at the midpoint of the clavicle.
Place the patient in a supine position, head-down. Turn the head to the contralateral side (if C-spine injury excluded). Adopt full asepsis. Introduce a needle attached to a 10 ml syringe, 1 cm below the junction of the middle and medial thirds of the clavicle. Direct the needle medially, slightly cephalad, and posteriorly behind the clavicle toward the posterior, superior angle to the sternal end of the clavicle (i.e. toward the suprasternal notch). Slowly advance the needle while gently withdrawing the plunger. When a free flow of blood appears, follow the Seldinger approach, as detailed previously. The catheter tip should lie in the superior vena cava above the pericardial reflection. Perform check chest X-ray to confirm position and exclude pneumothorax.
As listed for internal jugular venous cannulation. The risk of pneumothorax is far greater with this technique. Damage to the subclavian artery may occur; direct pressure cannot be applied to prevent bleeding.
Ensure that a chest X-ray is ordered, to identify the position of the line and to exclude pneumothorax.