Overview of Central Venous Access of the Subclavian Vein
In the US, doctors insert over 5 million devices called central venous catheters into patients each year. These devices are used in various medical and surgical treatments. Once a doctor decides that a patient needs a central venous catheter, there are several places in the body where it could be inserted. These include the internal jugular vein (a major vein in the neck), the subclavian vein (a vein found below the collar bone), the femoral vein (a large vein in the thigh), or they could use something called a peripherally inserted central catheter (which is a tube inserted into a vein in the arm to reach the larger veins near the heart).
Subclavian catheters, which go into the subclavian vein, can be either temporary or permanent. They can also vary in their design and may be simple, tunnelled (where the catheter is inserted into a vein and then advanced into the central veins – a technique intended to help anchor the catheter and reduce the risk of infection), or connected to an under-the-skin port (a special device that allows easy access to your bloodstream). They can have one or more channels (lumens), and the size (or diameter) of the catheter can also be different.
Anatomy and Physiology of Central Venous Access of the Subclavian Vein
The subclavian vein is a part of the body found on both sides of the upper chest, extending from the arms. It’s a direct extension of the axillary vein, which itself continues from the brachial vein in the arm. The axillary vein changes its name to the subclavian vein at the outer edge of the first rib. Right behind the subclavian vein is the axillary artery, which also transforms into the subclavian artery at the same spot.
The subclavian vein continues its journey beneath the collarbone moving towards the sternal notch (the dent in the middle of your chest where your ribs meet). It converges with the internal jugular vein (the vein in your neck) near the anterior scalene muscle to form the brachiocephalic vein, sometimes known as the innominate vein.
It’s important to note that the tip of the lung, also known as the pleural apex, is located just below the subclavian vein’s innermost part. It is particularly elevated on the left side, which raises the risk of lung injury (pneumothorax) during medical procedures involving this area. The thoracic duct, a crucial part of the lymphatic system, also ends at the intersection of the left subclavian and internal jugular veins, making it a possible injury site during procedures.
One benefit of accessing the subclavian vein from the left side is the smoother curve it makes towards the superior vena cava (the large vein carrying deoxygenated blood into the heart), which is located in the right area of the mediastinum (central part of the chest).
Why do People Need Central Venous Access of the Subclavian Vein
Central venous access is a medical procedure where a tube is inserted into a large, central vein in your body. This can be needed for a number of reasons including:
1. Difficulty in accessing the veins in your arms or legs. This means the doctors are unable to insert a typical IV into your arm or leg due to issues with the veins.
2. The need to administer strong medications that may damage smaller veins in the arms or legs. These can include chemotherapy drugs, some types of nutritional supplements that are given through a vein, or medications to raise blood pressure.
3. The need to closely monitor blood pressure inside your veins, the oxygen levels in your vein, or other heart-related parameters. Sometimes, a special type of catheter, known as a Swan-Ganz catheter, is used for detailed heart measurements.
4. A need to access the heart for a temporary heart pacing procedure. This is often needed when someone’s heart isn’t beating at the right rate or rhythm.
5. Kidney-disease-related treatments like hemodialysis, which cleanses the blood when the kidneys are not able to.
6. The need for a treatment called Extracorporeal Membrane Oxygenation (ECMO). ECMO is a treatment that uses a pump to circulate blood through an artificial lung back into the bloodstream, providing heart-lung bypass support outside of the body. It is typically used for patients with life-threatening issues affecting the heart and lungs.
When a Person Should Avoid Central Venous Access of the Subclavian Vein
There are a few situations where it might not be safe to perform a procedure involving central venous access. These situations are usually not absolute but depend on individual factors. These include:
If a person has unusual body structure, it might be more complicated or risky to locate or access the veins.
Conditions like coagulopathy and thrombocytopenia can be problematic. Coagulopathy is a disorder that affects the blood’s ability to clot, and thrombocytopenia is a condition of low platelet count in the blood. Both can make bleeding harder to control during or after the procedure.
If it is likely that the person might need to undergo hemodialysis currently or in the future, caution should be taken. Hemodialysis is a treatment for kidney failure where a machine cleans your blood. In this procedure, access to a vein (like the subclavian vein in the chest) is necessary. The process of getting to this vein can affect the blood flow rates necessary for hemodialysis.
Before deciding on a site for accessing the veins, the risks and benefits should be carefully weighed. This can help make the best choice for the safety and success of the procedure.
Equipment used for Central Venous Access of the Subclavian Vein
The equipment used for accessing the subclavian vein, which is located below your collarbone, depends on the specific requirements of the patient. Various kits are available, tailored to different needs. These can include equipment for inserting central lines (these are tubes inserted into a large vein for administering medication or drawing blood), large catheters (these are flexible tubes) for dialysis, large single tube lines used in trauma situations, permanent under-the-skin port kits (a port is a small medical appliance that is installed beneath the skin), and tunnelled catheters (this is a type of catheter that is longer term and is inserted under the skin from the insertion to the exit point).
All these procedures require some common supplies such as a needle, guide wire (a thin wire to guide in the placement of a medical device), knife, dilators (devices to enlarge an opening), and the catheter tube itself. Sterile conditions must be maintained throughout the process, so supplies like skin disinfecting solutions, personal protective gear, sterile draping, and dressings are also needed.
The catheters themselves can vary too. For instance, simple catheters with three pathways or ‘lumens’ can have different sized lumens and may be coated with substances to prevent infections. More long-term tunneled catheters often come with a cuff that is inserted underneath the skin to keep the catheter from being dislodged. Under-the-skin ports also come with various features, such as the ability to quickly inject contrast dye before a CT scan.
Understanding the reason behind placing the central venous catheter is vital to ensure that the correct type of catheter is chosen to best suit the patient’s needs.
Preparing for Central Venous Access of the Subclavian Vein
Doctors or nurses can usually insert a subclavian venous line, which is a tiny tube placed into a vein in your chest for delivering medicine, without extra help. But in a surgery setting, an extra person to pass tools and help with setup can be useful.
Before the procedure can start, it’s important to thoroughly clean the area of the skin where the line will be placed to ensure no surface germs get into your body. Special antiseptic solutions like betadine or chlorhexidine are used for this. Everyone in the room will wear a surgical mask and head cover to reduce the possibility of spreading germs. The doctor or nurse carrying out the procedure will also wear a sterile gown and gloves.
The patient is then positioned in a way called the “Trendelenburg position.” This method places the patient with their feet elevated slightly above their head, which makes the veins in the chest larger and easier to access while also helping to prevent any air bubbles from getting into the veins. A roll can be placed under the shoulder to help with access to the vein. However, this is skipped in cases where there might be a spine injury.
Whether the doctor or nurse chooses the right or left vein in your chest for this line depends on various factors. The right side is usually safer and less likely to result in a pneumothorax, where air gets between the lungs and chest wall causing breathing difficulties. But it also has a higher chance of the line not being correctly placed.
The area on the chest where the line is to be placed is cleaned thoroughly. Usually, the area from the top of the shoulders down to the nipple line and up from the chest to the chin is cleaned. After the cleaning solution is dry, sterile sheets are put in place so only the cleaned area is visible. The line and tools for the procedure are also prepared, with enough drapes to ensure the guide wire, which helps place the line, does not touch the bed after it’s inserted into the vein. Every catheter is flushed with sterile salt water before it’s used. A final check, known as a “time out,” is performed to make sure everything is ready and proper before the procedure starts.
How is Central Venous Access of the Subclavian Vein performed
In this procedure, the doctor uses local anesthesia, a type of medicine, to numb the area of your skin where the operation will take place. This process allows you to stay awake but not feel pain in the treated area. The area we’re talking about is around the collarbone, where an important blood vessel, the subclavian vein, is located.
Your doctor will check prominent body parts or “landmarks” on this area to guide the operation. For instance, if they are accessing the vein on your right side, they’ll use their left hand to feel the area underneath your collarbone. They will put one finger on the dip in the middle of your chest (sternal notch) and the thumb at the corner of your collarbone.
Next, they’ll insert a needle under your skin, right beneath the thumb, angled towards the sternal notch. A syringe is gently suctioned when trying to enter the vein. The doctor handles the needle in such a way that it moves in a straight line under your collarbone and between your first rib. It’s critical that they maneuver the needle in this way to avoid causing damage to any tissues or blood vessels beneath the surface.
If an adjustment of the needle direction becomes necessary, it should be done by pulling the needle back to the skin surface. Once they have successfully found the vein with the needle, dark red blood will rise into the syringe. This flow of blood should not pulsate.
Once the vein is accessed, a guide wire is pushed into the vein through the needle. This wire should be inserted gently. If there’s any resistance when inserting the wire, both the wire and needle are removed to avoid damage.
Once the guide wire is in properly, the needle is taken out. The next steps involve making a small cut in the skin to make room for a tool called a dilator and the catheter (a flexible tube) to pass. The dilator is then slipped over the wire while always keeping a hand on the wire. When the dilator is pushed into the vein, you may feel a little resistance as it penetrates the wall of the vein. Then, the dilator is removed, leaving the wire in place.
Finally, the catheter is placed over the guide wire. The doctor then confirms it’s in the right place by drawing out and releasing some fluid from all ports of the catheter. The catheter is then secured on your skin, and a sterile bandage is used to cover the wound.
This entire procedure facilitates treatments like dialysis, chemotherapy, and other kinds of long-term medications by providing a non-permanent access point to your veins. It’s a helpful procedure that can greatly improve the treatment process for a variety of medical conditions.
Possible Complications of Central Venous Access of the Subclavian Vein
When doctors add a tube into the vein under your collarbone (subclavian vein) to deliver medications directly into your bloodstream, it’s important to do it correctly to prevent complications. However, even when done right, some problems can still occur and it’s crucial to spot and address them as soon as possible. Standard practice is to follow the procedure with a chest x-ray.
Complications are divided into “immediate” ones, which happen during or soon after the insertion of the tube, and “delayed” ones, which occur later.
Immediate complications that might happen include:
1. Heart problems (cardiac complications), such as irregular heartbeats (arrhythmias), which can happen if the guidewire used to insert the tube touches the upper part of the heart called the right atrium. Arrhythmias can usually be stopped by adjusting the guidewire a little.
2. Blood vessel problems (vascular complications), such as injury to the blood vessels and formation of a blood-filled bump called a hematoma. In rare cases, the tube might end up in an artery instead of a vein, which might cause a stroke, blood clot, or bleeding. Occasionally, the needle might puncture the tissue of the lower part of the heart (right atrium) or other large vessels in the middle part of your chest (mediastinum).
3. Problems with the placement of the tube or catheter can cause it to get tangled with certain medical devices placed within the blood vessels, like a filter in the inferior vena cava (a large vein), or stitches during heart surgery. There are even cases where the guide wire used to place the tube gets lost or stuck.
4. Lung problems (pulmonary complications), such as a lung collapsing (pneumothorax), build-up of air in the chest (pneumomediastinum), injury to certain nerves that control your voice box, injury to the windpipe (tracheal injury), or air bubbles in the bloodstream (air embolism).
Delayed complications are mainly infections and problems with the tube working properly (device dysfunction):
1. Infections caused by bacteria can lead to severe reactions in the body, sometimes causing severe illness and even death.
2. Device dysfunction problems include the tube getting blocked; this usually occurs within the first week and can be treated using medicines to dissolve the blockage. The tube may also break, which could lead to serious problems, like heart infection, irregular heartbeats, puncture of the heart, or severe infection.
Overall, though there can be complications with subclavian venous access, using proper techniques can significantly reduce these risks.
What Else Should I Know About Central Venous Access of the Subclavian Vein?
Central venous access, or getting to the large veins located in the center of your body, is often required for a range of reasons. Both short-term and long-term catheterization, where a tube is inserted into your veins, call for central venous access. One common and reliable way to achieve this is through something called subclavian access, which is accessing a large vein located below the collarbone.
This technique is used quite often by medical professionals. Therefore, knowing how to do it is a useful skill for anyone working in healthcare. For you, the patient, it’s just good to know that it’s a safe and common procedure.
