Arterial Puncture and Arterial Line - Conditions, and Risk Factors

Introduction:

In emergencies, intensive care, and operating rooms, unstable and critically ill patients require repeated blood sampling and continuous blood pressure and hemodynamic monitoring. Arterial puncture and arterial line or catheterization is a procedure that gives access to the arterial blood continuously, so that blood pressure can be monitored at the bedside and repeated arterial blood samples can be obtained. Medications are not given through arterial lines (only intravenous or IV lines are used to give medications). The arterial catheter is kept in place (inserted in the artery) as long as needed and removed only when the patient is stable and it is safe to do so. There are several risks associated with arterial lines, and these complications can be avoided by trained staff by taking the necessary precautions.

What Are Arterial Punctures and Arterial Lines?

An arterial puncture is a procedure in which a needle or catheter is inserted into an artery (a blood vessel that carries oxygen-rich blood from the heart to body parts). This is an invasive procedure performed by well-trained medical professionals. An arterial line or arterial catheter is a thin and hollow tube inserted into the artery. These are also called ‘art-line’ or ‘A-line.’ Arterial catheterization is commonly performed in emergency rooms, intensive care units, and operating rooms to monitor blood pressure and to get blood samples for blood gas analysis and other lab tests.

When Are Arterial Lines Used?

Arterial lines are used for critically ill and unstable patients in emergencies such as shock, respiratory failure, severe blood loss, or complex surgeries requiring continuous hemodynamic monitoring. Arteries carry blood rich in oxygen to all the tissues and organs of the body. The arteries also have the highest blood pressure. In emergency and critical care units, these arterial lines prevent the need to repeatedly stick the patients with a needle. They enable multiple blood draws without disturbing the patient. The blood samples obtained are used for various lab tests and blood gas analysis (the levels of carbon dioxide and oxygen in the blood). These lines are connected to a bedside monitor to display the blood pressure changes (waveform) and facilitate close, continuous blood pressure monitoring.

What Are the Common Medical Conditions That Require Arterial Line Placement?

Arterial lines or catheterization is done for the following reasons:

1. Low Blood Pressure: When the patient has medical emergencies such as shock, it results in low blood pressure or hypotension. These are treated with fluids given intravenously and medications that can increase blood pressure. During the treatment, the doctors need to monitor the patient’s blood pressure continuously. Arterial catheterization provides an accurate, real-time, second-to-second measurement of blood pressure to modify treatment to keep the blood pressure at a safe, optimum level.

2. High Blood Pressure: In the critically ill, high blood pressure can be life-threatening. Monitoring the blood pressure continuously using an arterial catheter helps to lower the blood pressure gradually.

3. Severe Lung Related Illness and Conditions: In severe lung problems, the oxygen and carbon dioxide levels in the blood are altered. The increase in carbon dioxide levels and the decrease in oxygen levels lead to various complications. For such patients, it is essential to check the levels of these gases in the blood frequently (three to four times a day). When an arterial line is in place, it reduces the discomfort of multiple needle pricks while drawing blood for frequent arterial blood gas analysis. An arterial line also provides detailed information on blood gas levels. This helps to adjust the treatments like oxygen therapy or the need for a mechanical ventilator (the machine that helps to breathe).

How Are Arterial Lines Placed?

1. The patient is carefully assessed before the procedure. The patient’s skin is prepared before arterial line placement. The skin is cleaned, and a numbing agent is applied or injected into the area before the procedure.

2. The puncture site with the lowest risk of complication is selected. Commonly, the arterial line is inserted and placed in an artery in the wrist called the radial artery. Arteries in the elbow (brachial artery), groin (femoral artery), foot (dorsalis pedis artery), and other arteries in the wrist (ulnar artery) are also used to place an arterial line. Care is taken to ensure that the area has alternate circulation or blood supply to prevent complications due to clots in the lines or any other disturbance in the inserted artery.

3. The patient is positioned appropriately to allow proper access and visualization of the insertion site. Insertion is done with a proper sterile insertion or puncture technique. The needle or catheter size is selected based on the puncture site, the patient’s condition, and the procedure. The smallest practical size needle or catheter is used.

4. Once the blood vessel and the ideal puncture site are identified, the needle is inserted into the skin directly over the artery (with the bevel up). The needle is inserted slowly at a 30 to 45-degree angle till blood is seen in the hub, indicating entry into the artery. The catheter is inserted into the artery with the help of a guide wire and stabilized.

5. The presence of pulsatile blood flow confirms the proper placement of the catheter into the artery.

6. After the procedure, the patient is monitored, and bleeding at the site is checked and controlled by applying firm pressure.

7. The pressure tubing is attached to the catheter hub to verify the arterial blood pressure waves on the bedside monitor.

8. The puncture site is finally dressed and stabilized with proper protocol.

What Are the Risks of Arterial Lines?

There are several risks and complications associated with arterial lines, including the following:

1. Pain: Needle prick and insertion can cause discomfort and pain during arterial line placement. The discomfort is usually mild and reduces once the line is in place. A local anesthetic (numbing medicine) is used to lessen the pain of arterial line placement.

2. Infections: The arterial line or catheter is left inserted into the artery as long as required for treatment. Bacteria from the skin can enter the bloodstream through these catheters. The arterial lines that are in place for a longer duration have a greater chance of getting infected. Bandaging the skin and changing the tubes with special care can help reduce the chance of infection.

3. Blood clots: Blood clots can form in the tubes and tips of the arterial line. These can block blood flow to the tissues beyond the clot. In rare cases, if there is no alternate blood flow to the region, it can lead to the loss of a hand or leg. In order to prevent such issues, the arterial lines are placed in regions that have an alternate blood supply, and the catheter is regularly checked for clots. Also, blood flow to the region around the line is checked. The arterial lines are flushed with infusion fluid after blood draws to prevent clots.

4. Bleeding: Bleeding may occur during the insertion of the arterial line. Most bleeding is mild and stops automatically. The line is removed, and pressure is applied to control bleeding.

5. Nerve Damage: If the needle is directly inserted into the nerves, it may cause nerve damage.

Conclusion:

Arterial punctures and arterial lines are inserted by medically trained professionals for critically ill patients. These lines help to monitor blood pressure continuously for these patients. The blood pressure readings and waveform information is displayed on the bedside monitor. The arterial lines also enable multiple blood draws from the site, minimizing patient discomfort. The blood drawn is used for frequent blood gas analysis and other tests necessary to assess and treat the patient. A proper septic insertion technique, as per protocol, minimizes risks for the patients.