A central line is a medical device, also known as a central venous catheter, a long, flexible tube inserted into a large vein. It delivers medications, fluids, or blood products, and obtains blood samples. This device is useful for long-term treatments, frequent blood draws, or medications that could harm smaller veins.
Primary Insertion Sites
Central lines are placed where large veins are accessible. The internal jugular vein in the neck is a common site. The right internal jugular vein is often chosen for its larger diameter and straighter path to the heart, which reduces complication risks.
The subclavian vein, located beneath the collarbone in the upper chest, offers stable placement. However, careful technique is needed to avoid complications like lung puncture. The femoral vein in the groin is also used, especially in emergencies or when other sites are unavailable. While easily accessible, the femoral site may carry a higher infection risk.
Arm veins, such as the basilic or cephalic, are utilized for some central lines. The basilic vein is often preferred for arm insertions due to its larger size and more direct route to central circulation. These arm insertions provide an alternative to neck or chest sites and are less invasive.
The Significance of Central Veins
Central veins are selected over smaller, peripheral veins for several reasons. Central veins, like the vena cava, are larger and have higher blood flow. This allows for rapid delivery of large volumes of fluids or blood products, which is essential in emergencies.
Certain medications, such as chemotherapy drugs or concentrated nutrient solutions, can irritate smaller peripheral veins. Administering these through a central line quickly dilutes them in the larger blood volume, minimizing vessel irritation. Central access also facilitates frequent blood sampling without repeated needle sticks. This long-term access reduces the pain and discomfort often associated with multiple IV insertions.
Different Types and Their Placement
Various types of central lines exist, each suited for different durations and medical needs. Non-tunneled central venous catheters (CVCs) are for short-term use, typically less than two weeks. These lines are inserted directly into a vein in the neck, chest, or groin and remain outside the body at the insertion site. Placement is often performed at the patient’s bedside for immediate access.
Peripherally Inserted Central Catheters (PICC lines) are inserted into an arm vein. The catheter advances through arm veins until its tip reaches a large vein near the heart. PICC lines are suitable for medium to long-term use, often lasting weeks to months, allowing patients to receive treatment at home.
Tunneled catheters, such as Hickman or Broviac lines, are designed for long-term access, potentially remaining in place for months to years. These catheters are surgically inserted into a vein, often in the neck or chest, then “tunneled” under the skin before exiting at a separate chest site. This tunneling helps secure the catheter and can reduce infection risk.
Implanted ports, also called Port-a-Caths, offer discreet, long-term central access, capable of staying in place for years. The port, a small disc with a self-sealing top, is placed entirely under the skin in the chest or arm. A catheter connects the port to a large vein, and medications are administered by inserting a needle through the skin into the port’s reservoir.
The Ultimate Destination
Regardless of where a central line enters the body, its ultimate destination is a large vein close to the heart. The catheter’s tip is positioned in the superior vena cava (SVC), a major vein carrying blood from the upper body directly into the heart’s right atrium. This precise placement is confirmed through imaging, such as X-rays, after insertion.
Placing the tip in the SVC ensures medications and fluids are rapidly diluted in the central circulation. This central location allows for accurate measurement of central venous pressure, providing information about fluid status and heart function. Strategic positioning near the heart optimizes treatment effectiveness.