July 18, 2012

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ABIs: Do you or don’t you?

BY: NANCY MORGAN, RN, BSN, MBA, WOCN, WCC, CWCMS, DWC

You’ve identified your patient’s lower extremity ulcer as a venous ulcer. It has irregular edges, a ruddy wound base, and a moderate amount of drainage. The patient’s bilateral lower extremities are edematous. As a wound care clinician, you know sustained graduated compression is key to healing stasis ulcers and preventing their recurrence.

So are you ready to wrap? Not yet. As wound care clinicians, we always put our patients’ safety first. We need to be sure that compression won’t harm our patients and that there’s no underlying arterial component. Obtaining the ankle brachial index (ABI) gives us the information we need.

Obtain an ABI when pulses aren’t clearly palpable, on patients with lower extremity ulcers, and before starting compression therapy. The ABI rules out significant arterial disease and determines the amount of compression (if any) that can be applied safely. The normal ABI is ≥ 1.0 to 1.3.  An ABI of ≤ 0.9 indicates lower extremity arterial disease. An ABI of 0.6 to 0.8 signals borderline ischemia; ≤ 0.5 signifies severe ischemia.

For high-pressure compression (40 to 50 mm Hg) or moderate-pressure compression (30 to 40 mm Hg), the patient’s ABI should be above 0.8. For low- to moderate-pressure compression (25 to 35 mm Hg), it should be 0.5 to 0.8. With low-pressure compression (18 to 24 mm Hg), ABI should be at least 0.5. NEVER apply compression if ABI is less than 0.5! With your ABI completed, you now can apply compression safely.

When do you obtain an ABI in practice? In long-term care situations, how often do you obtain ABIs before applying compression? If you’re not obtaining ABIs, what’s the reason?

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DISCLAIMER: All clinical recommendations are intended to assist with determining the appropriate wound therapy for the patient. Responsibility for final decisions and actions related to care of specific patients shall remain the obligation of the institution, its staff, and the patients’ attending physicians. Nothing in this information shall be deemed to constitute the providing of medical care or the diagnosis of any medical condition. Individuals should contact their healthcare providers for medical-related information.

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12 thoughts on “ABIs: Do you or don’t you?”

  1. Roy B. says:

    I work in LTC and the content you offered is exactly how we deal with ABI

    1. Nancy Morgan says:

      Great to hear! Thanks for your post!

  2. Kim says:

    There are no hospitals, or clinics in my area that can do an ABI with a toe cuff. Many of the clients we would like to apply compression to heal these venous wounds have Diabetes. Any suggestions or information on where I can get a toe cuff?

  3. Most all medical suppliers can get the toe cuffs for you, however sometimes they are listed as “digit cuffs” or “penile cuffs” instead of toe cuffs.

  4. Patti Meyer says:

    Hi Nancy,
    I took a one-day seminar from you—loved it!
    Further clarification when to obtain ABI’s:
    If we plan to do compression–and the DP and PT pulses are clearly palpable and/or audible by a hand doppler, is there still a need to order ABI’s?
    Thanks,
    Patti Meyer

  5. Hey Patti,

    Nice to hear you enjoyed a seminar that I did. Thanks for the feedback.

    The quick answer to your question is Yes. Think of the ABI as required for diagnosis and treatment planning. True, good pulses are a decent indicator of blood flow to the area, but you need the exact ABI number to guide treatment. Studies tell us that the quality of the pulse itself can occasionally be misleading. And, from a legal perspective, you want to have that ABI reading documented to support your treatment choices in case something does not go well. It is not worth the risk to skip this step.

    Great question. I hope this helps.
    Nancy

  6. Patti says:

    Work in outpatient wound care clinic. Medial directors wants us to perform abi’s prior to applying compression. A WOCN nurse (not assoc. w/our clinic) who works at corp. level of hospital said no because it takes money away from vascular. Any evidence based articles you lead me to that will support this cause. Thank you very much. I never had this problem in an outpatient setting until working in this hospital system – frustrated and discouraged.

  7. Nancy Morgan says:

    Hey Patti,
    I received your question concerning the advice you have received about doing ABIs vs vascular testing. Kudos to your medical director who knows that this is a standard of care when it comes to compression therapy. The suggestion to refer all to vascular sounds like a business decision based on billing and making money as its not always a clinical necessity when a simple ABI can be done immediately. This could even delay treatment for the patient. It may not be needed for many patients. I hope you can work through this with all the powers that be so that you are not ordering unnecessary tests and/or delaying treatment for your patients.
    Nancy

  8. Ruth Hunting says:

    What if the patient cannot tolerate the process of obtaining an ABI? Like due to pain, or wounds. Also is it valid to do just one leg in such a case. I’m never really sure how accurate these tests are. It seems most of the ones I do are above 1. Thanks for the help.

  9. Nancy Morgan says:

    @Ruth
    All current evidence based Clinical guidelines state that the ankle pressure should be measured in both legs.
    2. If wound location is the problem, apply a protective dressing over the wound prior to placing the blood pressure cuff around ankle.
    3. If pain is the problem, consider premedicating the patient prior to procedure, if this does not work, do not perform ABI and consider and alternate diagnostic test.
    4. Link to American Heart Association Guidelines for ABI http://circ.ahajournals.org/content/126/24/2890.long
    5. Link to WOCN best practice guidelines for ABI: http://www.qsource.org/toolkits/pressureUlcer/docs/articles/whitePapers/abi.pdf

  10. Melanie says:

    My hospital based outpt wound clinic are seeing repeat pts with new and recurring venous ulcerations usually due to not wearing the compression stockings ordered after healing occurred. Is there a guideline on how often ABIs should be done again?

    1. Nancy Morgan says:

      Hi Melanie, I would suggest to look at the product insert of the various compression wraps many times they state how often to perform a ABI.
      Or at “any” change of condition in the wound status…..pt complaining of pain anything out of the ordinary would prompt me to do a ABI and do a reassessment to figure out what is going on.
      Performing repeat ABI’s are usually up to facility policy’s & procedures or professional clinical judgement.

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