Nursing Care of Arterial Lines
What is an arterial line? Also known as an art-line or a-line, an arterial line is a thin catheter that is inserted into an artery. It is most commonly used to monitor blood pressure directly and accurately, as with close and accurate titration of blood pressure medications. It is also used to obtain samples for arterial blood gas analysis (ABG’s), and is convenient when frequent blood samples are needed, so the patient does not have to be stuck multiple times.
Common insertion sites include radial, brachial, and femoral arteries.
The radial artery is the most common site and its advantages include easy access, accurate readings, easy bleeding control, collateral circulation, and fairly easy mobility for the patient. The disadvantages of the radial artery are the small diameter, making it difficult to insert, and possible nerve damage or thrombosis.
The advantages of the brachial artery are the large diameter, making it easier to insert, and fairly easy bleeding control. The disadvantages include immobilization of the limb, thrombosis, and limited collateral circulation. The advantages of the femoral artery include large diameter, making it easy to insert, even when the patient has low volumes. The disadvantages include difficulty visualizing, hard-to-control bleeding, immobilization of the limb, and prone to infection, due to the location. The dorsalis pedis is a riskier site that is not used very often.
Before inserting an arterial line in the radial artery, the modified Allen’s test is done to determine collateral circulation of the radial and ulnar artery. Have the patient elevate their hand and clench their fist for about 30 seconds. Apply pressure to the radial and ulnar arteries in the wrist to stop the blood flow to the hand. Still elevated, the hand is opened and should appear blanched. Release ulnar pressure while maintaining radial pressure to check if there is adequate blood flow back to the hand. If the hand quickly becomes warm and returns to its normal color, this is a positive Allen’s test, meaning that one artery alone will be enough to supply blood to the hand and fingers, therefore the radial artery can be used for the arterial line. If the hand remains pale and cold, it is a negative test, and an arterial line should not be placed in this location.
When monitoring a patient with an arterial line, the monitor will show waveforms in red. The systolic phase is when the heart contracts, the dicrotic notch reflects the closure of the aortic valve, and the diastolic phase is the pressure going down in diastole.
Waveforms can be overdamped or underdamped. The overdamped waveform may be caused by compliant tubing, loose connections, a blood clot at the cannula tip, or a cannula that is kinked or up against an arterial wall. The underdamped waveform can be caused by long stiff tubing, too many stopcocks, or a defective transducer.
Along with understanding waveforms on the monitor, the nurse is responsible for zeroing (calibrating) the arterial line. Zeroing the system tells the transducer to “ignore” the pressure from the atmosphere.
First, ensure the transducer pressure tubing and flush solution are assembled correctly and free of air bubbles. Place the transducer at the level of the right atrium (called the phlebostatic axis).
Turn the stopcock off to the patient, remove the cap – this opens to air (atmosphere). Press ‘zero’ to set the atmospheric pressure to a zero reference point. Replace the cap and turn the stopcock back to neutral (off to the atmosphere). Remember, whenever the patient position is altered, the transducer height should be altered to keep it at the level of the right atrium.
Zeroing the line should be done at each shift change, every 4 hours, after each time blood is taken from the art-line system, and as needed.
To continue your assessment, check for blood pressure accuracy. Do this by comparing the arterial line pressure reading with the NIBP reading to be sure they fall under similar parameters. Discrepancies of 20 mmHg or more are considered to be inaccurate. If the art-line system was to fail, the non-invasive reading can be used as a backup.
Another portion of caring for an arterial line is the neurovascular assessment that includes the 5 Ps:
Pain – check for pain in the extremity of the arterial line.
Pulses – check for collateral pulses and cap refill.
Pallor – check the hand for a nice pink color, don’t want to see paleness
Paresthesia – sensation (no numbness or tingling).
Paralysis – movement of the extremity.
Check your hospital policy regarding who can insert art-lines. In most cases, the RN will be assisting the doctor or respiratory therapist with the insertion of an arterial line, and the following equipment is needed:
500 cc normal saline bag (with air removed)
Transparent dressing and tape
Cable to connect transducer to monitor
The saline bag should be changed daily and the tubing system every 72 hours or according to your hospital guidelines.
When drawing blood from an arterial line, always waste the first 10 mL—this blood is hemodiluted and will not give accurate results. Use a shielded blunt cannula, turn the stopcock off to the saline bag, so it is open between the patient and the port you’re drawing from. Draw blood tubes without additives first, then tubes with additives, anticoagulation profiles, and ABG’s. Remember to zero the system after use and flush with saline to clear the tubing of blood.
Indications for removal of arterial line:
- Arterial pressure monitoring no longer needed
- Frequent blood sampling no longer necessary
- Neurovascular compromise
- Bleeding at the site
- Infection and sepsis
- Arterial line system failure (such as a kinked catheter or thrombus at the tip).
When removing the arterial line:
- Verify your MD order to remove the art-line.
- Check the coagulation studies (PT and PTT) prior to removing the art-line.
- Keep the tip sterile, in case a culture is needed.
- Apply direct pressure to the site for at least 15 minutes, then apply a pressure dressing to the site – checking for bleeding, hematoma, or bruising.
- Continue to assess the 5 Ps – pain, pulses, pallor, paresthesia (sensation), paralysis (movement)
Thank you for watching this video tutorial on the nursing care of arterial lines!