Hospital Medicine

Arterial lines

I. Problem/Challenge

Arterial lines are vital in critical care medicine, enabling:

  1. Continuous arterial pressure monitoring to facilitate the titration of vasopressive and inotropic medications.

  2. Frequent arterial blood gas measurements for ventilator management in patients with respiratory failure.

II. Identify the Goal Behavior

Indications for placement of an arterial line include the need for continuous blood pressure monitoring in a hemodynamically unstable patient on vasopressors, or inotropic support and/or the need for frequent and reliable arterial access for serial blood gas sampling to enable ventilator management in critically ill patients with respiratory failure.

Arterial line placement is contraindicated if there is a superficial infection overlying the placement site or if there is trauma proximal to the insertion site. Most experts recommend use of the Allen test (see description below) to verify collateral circulation prior to arterial line placement, however, this has not been validated with a large study, and in fact some studies have demonstrated adequate perfusion with duplex ultrasonography in the setting of an abnormal Allen test.

Additionally, there isno data that performing the Allen test results in reduced ischemic complications of radial artery cannulation. Severe ischemic complications may occur even in the setting of a normal Allen test. Conversely, development of radial artery occlusion in the setting of an abnormal Allen test can occur without other adverse outcome.

Once an arterial line is in place, the site should be assessed frequently - at a minimum, every 4 hours, to ensure no complications develop (including vascular compromise, infection, hematoma, bleeding, and infiltrate). The arterial line should be removed as soon as possible.

III. Describe a Step-by-Step approach/method to this problem.

  1. Discuss the risks and benefits of the procedure with the patient (or health care proxy) and obtain written informed consent.

  2. Perform an Allen test to assess for collateral circulation.

    • Ask the patient to make a fist.

    • Apply pressure to the radial and ulnar arteries to occlude both.

    • Ask the patient to unclench the fist. The hand will appear blanched and pale.

    • Release ulnar pressure.

    • The test is normal (i.e. there is adequate ulnar supply to the hand) if color returns to the hand within 7 seconds.

    • If the Allen test is abnormal, you will need to weigh the risks and benefitsthe procedure in your particular patient, and use your clinical judgement to determine whether to procede with arterial line placement. (Keep in mind the many limitations of the Allen test, as listed above.)

  3. Gather your supplies: wrist board, rolled towel, sterile wash (such as chloraprep swabs), 1% lidocaine solution and syringe, sterile towels, sterile drape, personal protective equipment including sterile gloves and facemask with eyeshield, the arterial catheter, needle, and transduction system, tape, and sutures.

  4. Position the patient's arm: place the hand and wrist on the arm board, palm up. It is useful to place a small towel or rolled bandage under the wrist so that the hand is dorsiflexed, moving the radial artery into a more superficial position. Tape the wrist into position.

  5. Prep and drape the wrist in the usual sterile fashion. Sterile gloves and a facemask with eye shield should be worn. Palpate the radial artery. Consider using 1% lidocaine SC at the insertion site, especially in patients who are conscious.

  6. Slowly insert the needle at a 30 to 45 degree angle directly over the palpable pulse. Advance gradually until a flash of pulsatile blood flow is seen. At this point, decrease the angle of the catheter to about 15 degrees and then slowly advance the catheter over the needle into the artery. Remove the needle and connect the catheter to the transduction system.

  7. Secure the catheter in place via suture or tape; cleanse the area and cover with an occlusive dressing.

  8. Reassess to ensure adequate perfusion distal to the catheter; remove the catheter immediately if there is any evidence of ischemia.

IV. Common Pitfalls.

Common pitfalls include inability to cannulate the artery, inability to pass the catheter due to arterial spasm or development of a hematoma. If this occurs, select another site for catheter placement (on the other arm or at a site proximal to your first attempt). If you are able to obtain a flash of arterial blood but not able to advance the catheter, try a more shallow angle of entry (10 degrees), and/or a slight advancement or withdrawal of the needle to ensure the tip is directly in the vessel lumen.Complications of arterial line placement include vascular compromise, bleeding, hematoma development, and, uncommonly, infection. The line should be reassessed regularly to ensure no complications have developed and removed as soon as possible.

V. National Standards, Core Indicators and Quality Measures.

No national standards/benchmarks have been established yet.

VI. What's the evidence?

Abu-Omar, Y, Mussa, S, Anastasiadis, K, Steel, S, Hands, L, Taggart, DP. "Duplex ultrasonography predicts safety of radial artery harvest in the presence of an abnormal Allen test". Ann Thorac Surg. vol. 77. 2004. pp. 116-119.

Fuhrman, TM, Pippin, WD, Talmage, LA, Reilley, TE. "Evaluation of collateral circulation of the hand". J Clin Monit. vol. 8. 1992. pp. 28-32.

Tegtmeyer, K, Brady, G, Lai, S, Hodo, R, Braner, D. "Videos in clinical medicine. Placement of an arterial line". N Engl J Med. vol. 354. 2006. pp. e13.

Traore, O, Liotier, J, Souweine, B. "Prospective study of arterial and central venous catheter colonization and of arterial- and central venous catheter-related bacteremia in intensive care units:". Crit Care Med. vol. 33. 2005. pp. 1276-1280.

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