Blood delivers oxygen, vitamins, hormones and other nutrients to the body’s cells. Arteries carry oxygenated blood from the heart to the rest of the body. A large artery called the aorta arches upward from the top of the heart and descends through the middle of the torso. Smaller arteries branch off from the aorta and distribute blood to body tissues.
Blood that is low in oxygen is channeled into the body’s venous system, which returns blood to the heart. From the veins, blood is pumped into the vena cava, the body’s large central vein, and back into the right side of the heart.
Like oxygen and nutrients, medications are also delivered to the body’s cells through the bloodstream. By using a hypodermic needle to inject drugs through a vein in the arm and into the bloodstream, medications can be transported very quickly through the body to the drug’s site of action, or place in the body at which the drug is needed.
In some cases, using a needle to inject medication may not be the best intravenous delivery method. For example, therapies for certain medical conditions may require daily needle sticks over a period of weeks or months, while other drugs require quick dilution in large amounts of blood. When a person has weak arm veins, or to prevent the pain and potential damage to small blood vessels caused by repeated needle punctures or caustic drugs, doctors may use venous access devices to deliver drugs directly into the bloodstream.
VENOUS ACCESS DEVICES
Venous access devices are small medical appliances that can be connected directly to veins. Access devices use a catheter, or a long, thin, hollow tube that serves as a kind of artificial vein, with one end of the catheter inside a vein in the body, and the other end very close to the surface of the skin or outside the skin. The catheters are made of silicone, a soft material that does not irritate body tissues. Access devices can be inserted directly into a vein in a person’s arm, neck, or chest and left in place for long periods of time. Using the part of the device outside or near the surface of the skin as a kind of port into the venous system, health care professionals can:
- Administer intravenous drugs
- Supply hydrating and nutritional fluids
- Draw blood samples
- Transfuse blood or blood products
THE VEINS OF THE ARMS AND CHEST
Access devices are usually placed in veins with strong blood flow on the right side of a person’s body. The upper right side of the body is typically used because it provides convenient access to the part of a person’s vena cava that connects with the right atrium of the heart.
In the arm, the basilic and brachial veins run along the inside of the arm near the biceps, and the cephalic vein runs along the outer part of the upper arm where it joins the brachial vein to form the axillary vein in the shoulder. The axillary vein continues with the subclavian vein, which runs across the front of the chest below the shoulder, and the subclavian vein enters the superior vena cava, the top part of the body’s central vein. The internal jugular vein run down through the neck and joins the top of the vena cava, which connects to the right atrium of the heart itself.
The femoral vein, which is accessed in the groin, may also be used to place a venous access device, but is most commonly used when children require an access device.