A central venous catheter (CVC) is a medical device used to access major veins near the heart, typically when long-term intravenous therapy is needed or when peripheral veins are insufficient. The subclavian approach involves inserting a catheter into the large vein located beneath the collarbone. This technique provides a direct route into the body’s central circulation for administering complex treatments. CVC use is reserved for serious medical conditions where the benefits of central access outweigh the inherent risks associated with penetrating a major vessel.
Defining the Subclavian Central Line
The subclavian central line is a catheter threaded into the subclavian vein, which runs under the clavicle, or collarbone. This vein merges with the internal jugular vein to form the brachiocephalic vein, draining into the superior vena cava (SVC), a large vessel leading to the heart’s right atrium. Since the catheter tip rests in the SVC, the line provides immediate access to the body’s core circulation. The subclavian line is useful for several therapeutic needs, including the delivery of total parenteral nutrition (TPN), a concentrated solution that can damage smaller peripheral veins.
- Prolonged administration of medications, such as antibiotics or chemotherapy agents.
- Rapid infusion of large volumes of fluids during critical situations like trauma or severe shock.
- Specialized monitoring, such as measuring central venous pressure (CVP).
The Insertion Process
The placement of a subclavian central line requires a strictly sterile environment to minimize infection risk. The patient is typically positioned lying flat or in a slight head-down position (Trendelenburg), which helps distend the vein and reduce the chance of an air embolism. The clinician performing the procedure wears a sterile gown, gloves, mask, and cap, and the patient is covered with sterile drapes to create a clean operating field.
The area beneath the collarbone is numbed using a local anesthetic, such as lidocaine. While the procedure often relies on anatomical landmarks, ultrasound imaging is becoming more common to visualize the vein and surrounding structures.
Placement generally follows the Seldinger technique. A hollow needle is inserted to access the vein. Once a flow of venous blood confirms correct positioning, a flexible guidewire is advanced into the SVC. The needle is removed, and a small incision is made. A dilator is briefly passed over the wire to widen the tissue tract. Finally, the central line catheter is threaded over the guidewire and secured in place. A chest X-ray is mandatory immediately after the procedure to confirm the catheter tip’s position in the SVC and to check for mechanical complications, such as a collapsed lung.
Post-Procedure Care and Management
To ensure function and prevent complications, the insertion site must be meticulously cleaned and covered with a sterile dressing. Routine dressing changes follow strict aseptic protocols, typically occurring every five to seven days, or sooner if the dressing is soiled, wet, or detached from the skin. The site is routinely assessed for signs of local infection, including redness, tenderness, warmth, or drainage.
Each channel, or lumen, of the catheter must be regularly flushed with saline solution to maintain patency and prevent blood clots or occlusions. Sterile technique is employed every time a port is accessed for administering medications or fluids, often involving specialized disinfecting caps. The central line remains in place only as long as medically necessary, with necessity evaluated daily. Removal is a simple procedure performed by a trained clinician. After the catheter is withdrawn, sustained pressure is applied to the insertion site to seal the vein and prevent bleeding.
Understanding the Major Risks
The placement of a subclavian line carries specific risks related to the complex anatomy of the chest. The most recognized mechanical complication is pneumothorax, or a collapsed lung, which occurs when the insertion needle inadvertently punctures the pleura. This risk is specific to chest and neck lines because the apex of the lung sits close to the target vein, with reported rates ranging from 0.5% to 2% of insertions.
A related, less common mechanical risk is hemothorax, where blood collects in the chest cavity, typically from injury to the subclavian artery or a major vein. The subclavian approach has a lower incidence of accidental arterial puncture compared to the internal jugular site. Another immediate danger is air embolism, which occurs if air enters the central vein through the needle or open catheter lumen, potentially causing a blockage in the heart or lungs.
The most serious long-term risk is a Central Line Associated Bloodstream Infection (CLABSI), where bacteria travel along the catheter and enter the bloodstream, causing a serious systemic infection. The subclavian site generally shows a lower rate of infection compared to lines placed in the internal jugular or femoral veins. Another non-infectious complication is deep vein thrombosis (DVT), a blood clot forming around the catheter that can block blood flow or potentially travel to the lungs.