Arterial Blood Pressure Monitoring

Definition

Direct arterial blood pressure monitoring is a method by which arterial blood pressure is monitored by inserting a needle cannula into a suitable peripheral artery, preferably the radial, brachial or femoral artery in critically ill patients who have severe hypertension or hypotension. The cannula is connected to a transducer that converts the pressure waves to electrical waves and is displayed as a continuous waveform on the monitor.

Radial artery cannulation procedure

The radial artery cannulation is discussed in this manual as it is by far the most commonly used site for invasive arterial blood pressure monitoring. The procedure is essentially performed by a surgeon, but we will be discussing the nursing responsibilities.

Indications

• Patients post-cardiac surgery/high-risk surgery.
• Patients who require frequent blood samples.
• Hypotensive patients who are on vasopressor infusions to support blood pressure.

Contraindications

• Vascular disorders to the extremities, such as Buerger’s disease.
• Fracture or skin lesions to the extremity.
• Diminished or absent pulses to the extremity.
• Infections at the site of placement of the extremity.

Common complications

There are some common complications that can happen irrespective of the site used. They are as follows:

• Hematoma formation.
• Circulatory compromise.
• Infection to site.
• Inadvertent administration of medication through the arterial line.
• False reading if tubing is kinked or clotted.
• Dislodgement of cannula.
• Bleeding if stop cocks are not turned in the right position.
• Massive ecchymosis.
• Air embolism.

Arterial blood pressure monitoring sites

The most common sites for direct arterial blood pressure monitoring are as follows:

1. Radial artery.
2. Brachial artery.
3. Femoral artery.
4. Dorsalis pedis artery.

The radial artery and the femoral artery are the most common sites used for direct arterial blood pressure monitoring (approximately 90% of all arterial blood pressure monitoring sites).

Equipment Needed

1. Catheter kit that includes artery cannulation catheter, sterile drapes, sterile dressing, and skin cleansing solution.
2. Additional supplies: Transducer kit, 500 mL, normal saline bag, sterile gloves, sterile mask, and sterile gowns.

Procedure Steps

The arterial blood pressure monitoring procedure involves inserting a catheter into an artery to provide continuous, real-time blood pressure measurements. Here’s an overview of the process:

1. Patient Preparation:
   • Confirm the patient’s medical history, including bleeding disorders or vascular conditions.
   • Ensure the patient has followed fasting guidelines if required.
   • Explain the procedure and obtain informed consent.
2. Equipment Setup:
   • Gather sterile supplies, including an arterial catheter, pressure transducer, and flush system.
   • Ensure the monitoring system is calibrated and functioning properly.
3. Catheter Insertion:
   • Select an appropriate artery (commonly the radial, femoral, or brachial artery).
   • Perform a modified Allen test if using the radial artery to assess collateral circulation.
   • Use sterile technique to insert the catheter and secure it in place.
4. Monitoring and Calibration:
   • Connect the catheter to the pressure transducer and monitoring system.
   • Zero the transducer to ensure accurate readings.
   • Continuously monitor systolic, diastolic, and mean arterial pressure.
5. Post-Procedure Care:
   • Apply pressure to the insertion site to prevent bleeding.
   • Monitor for complications such as infection, thrombosis, or hemorrhage.
   • Provide instructions for catheter maintenance and removal.

Preprocedural nursing responsibilities

1. The procedure is invasive, so an informed consent should be obtained from the patient or next of kin.
2. Check arterial circulation of hand. Usually, the non-dominant hand is selected for the cannula insertion. However, it is important to consider the circulatory status of the hand before initiating procedure.
3. Perform the Allen’s test to check blood flow and perfusion through the ulnar artery.
4. Inform the surgeon about the results of the Allen’s test.

Nursing responsibilities

The procedure is usually done in the operating room along with some other surgeries or as a part of an emergency measure in the intensive care unit or emergency room. The most important nursing responsibility is to maintain an aseptic environment under whichever circumstances the procedure is performed.

1. Assemble the needed equipment.
2. Set up pressure monitoring system.
3. Assemble the kits in the order of use.
4. Insert flush solution bag into the pressure bag which is hung on an IV pole. Spike the solution bag with the noncompliant-noncompressible rigid tubing which is included in the arterial monitoring kit.
5. Fix the transducer to the transducer holder (which is set at the level of the right atrium). Make sure that the tubing going to the patient is on the upper side when fixing the transducer in the holder.
6. Inflate your pressure bag to 250-300 mm of mercury.
7. Prime the line till it is free of any air bubbles and flowing freely.
8. Flush the entire system by using the quick flush system.
9. The transducer cable is then connected to the monitor.
10. Prepare insertion site with hospital approved antiseptic solution and drape with sterile drapes.
11. Maintain sterile technique throughout.
12. Connect the pressure monitoring tubing immediately after the backflow of blood is seen in the newly inserted arterial catheter. Flush the system using the fast flush device, thus flushing the blood back into the artery.
13. Place transducer level at the right atrium of the heart.
14. Zero the system (turn the stop cock off to the patient at the level of the transducer so that the system is now open to atmospheric air. Then press “zero” on the monitor so the atmospheric pressure is now the reference point for the system).
15. After zeroing the system, ensure stopcock is turned off to the atmospheric air, i.e., open between patient and transducer so normal blood pressure reading is obtained on the monitor.
16. Ensure that there are no kinks or air bubbles through the entire system and that the stopcocks are turned in the right position to ensure accurate reading and prevent complications.
17. Verify waveform on the monitor and ensure accuracy of reading.
18. Apply sterile dressings on the catheter insertion site as per hospital policy after surgeon applies sutures or a securement device.
19. Ensure labeling of arterial line at stopcocks to prevent accidental manipulation or administration of medication through the line.

To ensure the accuracy of readings and proper working of the system, the nurse has to ensure that the leveling and zeroing of the system are done every shift or whenever the patient’s position is changed to ensure accuracy in reading.

Advantages of Radial Artery Cannula Placement

1. Radial artery is superficial and easy to access and visualize.
2. There are two arteries supplying the hands, and hence, there is lower risk of vascular insufficiency following cannulation.
3. Easier to immobilize.
4. Comfortable to patient if non-dominant hand is used.

Disadvantages of Radial Artery Cannula Placement

• Thrombus formation with prolonged use.
• Vascular compromise to the hand.
• Nerve injury during cannulation.
• Hematoma formation.
• Infection.
• False high systolic reading as a smaller gauge cannula is used for radial artery cannulation.

Special Consideration

• Confirm the patient’s medical history, including bleeding disorders or vascular conditions.
• Perform a modified Allen test if using the radial artery to assess collateral circulation.
• Verify if the patient is on blood-thinning medications, as these may increase the risk of bleeding.
• Adjust medications as per the healthcare provider’s instructions.
• Explain the procedure to the patient, addressing any concerns or questions.
• Obtain informed consent and reassure the patient to reduce anxiety.
• Maintain strict sterile conditions to minimize the risk of infection.
• Use sterile gloves, syringes, and antiseptic solutions.
• Observe the patient for signs of discomfort, vasospasm, or complications during the procedure.
• Ensure the patient remains still to prevent accidental injury.
• Use the correct angle and technique for arterial catheter insertion.
• Avoid excessive probing to minimize tissue damage.
• Apply firm pressure to the puncture site for at least 5 minutes or until bleeding stops.
• Monitor for the formation of a hematoma and take appropriate action if it occurs.
• Monitor the patient for delayed complications, such as bleeding, infection, or arterial occlusion.
• Provide clear instructions for follow-up care and signs to watch for, such as numbness or discoloration.

REFERENCES

1. Annamma Jacob, Rekha, Jhadav Sonali Tarachand: Clinical Nursing Procedures: The Art of Nursing Practice, 5th Edition, March 2023, Jaypee Publishers, ISBN-13: 978-9356961845 ISBN-10: 9356961840
2. Omayalachi CON, Manual of Nursing Procedures and Practice, Vol 1, 3 Edition 2023, Published by Wolters Kluwer’s, ISBN: 978-9393553294
3. Sandra Nettina, Lippincott Manual of Nursing Practice, 11th Edition, January 2019, Published by Wolters Kluwers, ISBN-13:978-9388313285
4. Adrianne Dill Linton, Medical-Surgical Nursing, 8th Edition, 2023, Elsevier Publications, ISBN: 978-0323826716
5. Donna Ignatavicius, Medical-Surgical Nursing: Concepts for Clinical Judgment and Collaborative Care, 11th Edition ,2024, Elsevier Publications, ISBN: 978-0323878265
6. Lewis’s Medical-Surgical Nursing, 12th Edition,2024, Elsevier Publications, ISBN: 978-0323789615
7. AACN Essentials of Critical Care Nursing, 5th Ed. Sarah. Delgado, 2023, Published by American Association of Critical-Care Nurses ISBN: 978-1264269884.
8. Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/

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