What to Know and Expect If You Need an Arterial Line
Key takeaways:
An arterial line is a small, flexible tube a healthcare provider places in an artery. They allow care teams to closely monitor someone’s blood pressure.
Arterial lines are most common in the intensive care unit (ICU) or during surgery. They help providers know how much medication to give someone. They also allow for frequent blood draws without extra pokes.
The procedure to insert an arterial line is fast and easy. Complications are rare, but they include bleeding, infection, and blood clots.
An arterial line is a thin, flexible tube a healthcare provider places into one of your arteries. Sometimes people shorten it to “art line.” It calculates your blood pressure every time your heart beats. This means it provides a continuous, more accurate blood pressure than a blood pressure cuff.
Teams in the intensive care unit (ICU) most often use it when someone is critically ill and needs very close monitoring. It’s also helpful in some surgeries, like ones on the brain or heart.
If parts of this sound familiar, it may be because arterial lines share some similarities with intravenous (IV) lines. We'll go over what sets them apart and cover when and why healthcare teams use arterial lines.
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Why are arterial lines useful?
Arterial lines are useful in several scenarios:
Low blood pressure: When someone is very sick or having a big surgery, their blood pressure can get really low. In these cases, they need medications and IV fluids to help increase their blood pressure. An arterial line is useful for knowing how much medication or IV fluids their body needs.
High blood pressure: Similar to low blood pressure, arterial lines are also helpful when someone’s blood pressure is dangerously high. This way, providers know exactly how much medication they need to lower their blood pressure safely.
Critical illness: When someone is in the ICU and on a mechanical ventilator (breathing machine), providers need to closely watch their lungs. They do this by taking frequent blood samples from the artery. They can then measure someone’s oxygen and carbon dioxide levels in the blood.
Frequent lab testing: There are many medical conditions that need close blood monitoring. Instead of using a needle to draw new blood every time, an arterial line can draw a blood sample without another poke.
Procedures: Cardiologists and radiologists sometimes use arterial lines to perform their procedures, like a heart catheterization.
How do you insert an arterial line?
Providers can insert arterial lines in several different locations. But most often they place them in the radial artery in your wrist. But your provider may also insert one higher up in the arm, in the groin, or even in the foot.
When inserting an arterial line, a provider often uses an ultrasound to help guide them. And this technique is becoming more popular because ultrasounds increase the chance of a successful placement. But providers are also trained to insert them in the right place by feeling for your pulse.
The basic steps to placing an arterial line are similar to those for placing a central line or a big IV:
A provider checks multiple locations to find the best spot for the arterial line. They’ll use an ultrasound or feel for a good pulse.
They clean the skin over the selected spot with an antibacterial solution. If using the wrist artery, the provider will secure your hand to reduce movement during the procedure.
They’ll place clean towels or a drape over the area to keep it as clean as possible.
The provider will insert a small amount of numbing medication in the area. This makes the rest of the procedure more comfortable. You may feel a brief pinch or sting when they inject the medication under the skin.
The provider carefully uses a needle to enter the artery. Once inside the artery, they guide the flexible catheter over the needle into the right place. Then they remove the needle.
They connect the catheter to tubing and secure it in place. No needles or sharp objects remain after the procedure is complete.
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What complications can occur from an arterial line?
Just like any medical procedure, arterial lines have some risks. Fortunately, serious complications occur in less than 5% of cases. They include:
Pain during placement: A needle is used to get the catheter in the right place, so some pain or discomfort can occur. The numbing medication helps prevent this.
Bleeding: Since the catheter goes in an artery that carries fast-flowing blood, bleeding can occur during placement and removal of the line. Most of the time the bleeding stops on its own with a little pressure.
Infections: Any catheter in the body increases the risk of infection of the surrounding skin or the blood. This risk goes up the longer the catheter remains there. Providers use a sterile technique during the procedure to reduce the chance of an infection.
Blood clots: Sometimes a blood clot forms at the tip of the arterial line catheter. Usually this doesn’t cause significant problems. On very rare occasions, the surrounding skin develops issues from a lack of oxygen (ischemia). But the provider will check blood flow to the area regularly to reduce this risk.
What is the difference between an arterial line and a central line?
Central lines are big IVs in your neck. There are two main differences between an arterial line and a central IV line:
Arterial lines are inserted into an artery — the blood vessels that carry blood away from the heart. Central lines (and all IVs) are inserted into a vein — the blood vessels that carry blood back to the heart.
Central lines and IVs are used to give medications, but arterial lines are not. Healthcare teams use them for monitoring.
Providers often use these two devices together, especially since the arterial line helps the provider know how much medication to give through the IV. But not everyone needs both. They can be used separately or together.
The bottom line
Arterial lines are a helpful tool for people who are critically ill or undergoing surgery. Arterial lines monitor your blood pressure with every beat of your heart. And they often save you from having to be poked every time your provider orders lab work. If you have any questions or concerns about arterial lines, be sure to bring them up with your provider before the procedure. That way you’ll understand why you need one and what to expect with the procedure.
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References
American Thoracic Society. (2018). Arterial catheterization.
Bhattacharjee, S., et al. (2018). Comparison between ultrasound guided technique and digital palpation technique for radial artery cannulation in adult patients: An updated meta-analysis of randomized controlled trials. Journal of Clinical Anesthesia.
Pierre, L., et al. (2022). Arterial lines. Stat Pearls.
Shiloh, A. L., et al. (2010). Ultrasound-guided arterial catheterization: A narrative review. Intensive Care Medicine.
Thiele, R. H., et al. (2015). Inter-device differences in monitoring for goal-directed fluid therapy. Canadian Journal of Anesthesia.
Zarbiv, S., et al. (2018). When is a peripheral arterial catheter (A-Line) indicated in my ICU patient? Chest.
