Arterial wounds in phase 1 of peripheral arterial disease

The most important factor in wound healing is adequate circulation to the wounded tissue. Lower extremity wounds caused by arterial insufficiency are usually a result of peripheral arterial disease, and are characterized by location at the distal toes or fingers, dry or necrotic tissue, little if any drainage, no granulation tissue, and pain. Non-invasive tests that are used to determine the treatment plan and interpretation of the results are presented with this case study, as well as a conservative care plan.

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May 17, 2019
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Arterial Wounds

Week 4 Wound Conumdrums

 

The toe wound in this photo was on a 72 year-old-male with a history of Type 2 diabetes, hypertension, hyperlipidemia, and mild CVA approximately 2 years ago from which he has fully regained function.  He is independent in all activities, including walking at the community level without an assistive device.

What is the most likely cause of this wound?

  • Pressure on the great toe from shoes that were too tight.
  • Lack of sufficient circulation to the tissue.
  • Poorly controlled diabetes.
  • Possibly all of the above.

Answer D

Approximately 10% of Americans over 70 years of age have peripheral arterial disease (PAD), and more than 20% of those over 80 years of age have PAD, with the prevalence higher in men than in women.[1]  The most frequent cause of PAD is atherosclerosis, a disorder that is prevalent in patients with Type 2 diabetes.  Frequently the first indication that an individual may have PAD is the presence of a non-healing wound on the distal extremity – the wound is not getting sufficient oxygen to initiate and sustain the healing process.  PAD has 3 crucial phases:

Phase 1 – collateral circulation is not sufficient for the metabolic needs of the extremity.

Phase 2 – activity or exercise causes relative ischemia and pain, termed intermittent claudication.

Phase 3 – patient experiences resting pain, gangrene, or dependent leg syndrome, termed critical limb ischemia.

Evaluation of any lower extremity wound includes a vascular screening, beginning with palpation of the dorsalis pedis and posterior tibialis pulses.  If they are diminished, a referral to a vascular surgeon is advised, and vascular testing is indicated to determine the appropriate treatment plan.  Two tests used most frequently are the ankle-brachial index (ABI) and the transcutaneous oxygen perfusion (TcPO2).  The ABI is a ratio of the ankle systolic pressure to the brachial systolic pressure, and the TcPO2 is a measure of skin oxygenation.  Guidelines for treatment with both tests are as follows:

 

 

Ankle-brachial index

>1.3 Non-reliable in patients with diabetes due to calcification of the arteries.  Toe pressures are used instead.

1-1.3 May indicate venous hypertension

1-1.2 Normal

0.8-1 Mild PAD; safe to perform standard wound care, including debridement; however, healing may be delayed.  Compression is safe to use if edema is present.

0.5-0.8 Moderate PAD; compression is contraindicated if <0.6; modified compression may be used if >0.6.  Debridement would depend on TcPO2 and/or presence of infection.

<0.5 Severe PAD; debride only infected tissue.  Compression is contraindicated.

<0.2 Tissue death will occur.

 

Transcutaneous oxygen perfusion

60-90 mmHg, Normal (chest values used for each patient)

>40 mmHg, Desired for timely healing

> 30 mmHg proximal to the wound, Wound can be debrided

< 30 mmHg proximal to toe wound, Wound should not be debrided until revascularization is accomplished

20-30 mmHg proximal to wound (not toes), Healing will be delayed

<20 mmHg proximal to any wound, Unlikely for healing to occur.

 

The vascular surgeon will determine if revascularization is required based on ABI, arterial duplex test, or arteriography results, and may be accomplished either with stenting of the occluded artery or with by-pass surgery.  Wound care is determined by the results of the vascular testing, and in the case of the patient described above, would involve cleansing of the wound, removal of any loose debris (the pink thread from patient’s sock, detached devitalized epidermis), exploration of the center of the wound for signs of infection, protection of the toes from further friction or pressure (including adaptive footwear), and a protective dressing.  The dorsal PIP joint also appears to have some skin changes indicating prolonged friction or pressure and also needs to be addressed.

In addition, discussion of diabetes management is an integral part of the patient’s care and a referral to a nutritionist advised if the patient is having difficulty controlling the blood sugars.  Recommendations for exercise depend on the patient’s vascular and cardiac status, and if surgery is required, may be limited to functional gait only.  Exercise alternatives for managing the diabetes would be upper extremity ergometer or riding on a stationary bicycle.

Discussion of treating patients in Phases 2 and 3 of PAD will follow in the next 2 weeks.

Additional information on treating patients with wounds secondary to arterial insufficiency, including etiologies other than PAD, can be found at the following:

Woelfel S, Ochoa C, Rowe VL.  Vascular wounds. In Hamm R (Ed), Text and Atlas of Wound Diagnosis and Treatment: 2nd edition.  New York: McGraw Hill Education.  2019, 101-143.  Available at https://accessphysiotherapy.mhmedical.com/book.aspx?bookid=1334

Norgren L, Hiatt WR, Dormandy JA, et al.  Inter-society consensus for the management of peripheral arterial disease (TASC II). J Vasc Surg.  2007;45(suppl S):S5-67.  Available at https://www.jvascsurg.org/article/S0741-5214(06)02296-8/pdf.  Accessed 5/16/2019.

Aboyans V, Criquic MH, Abraham P et al. Measurement and interpretation of the ankle-brachial index. Circulation. 126:24. Available at doi/full/10.1161/CIR.0b013e318276fbcb. Accessed 5/16/2019.

[1] Center for Disease Control.  Peripheral arterial disease (PAD): fact sheet.  https://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_pad.htm

 

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Rose Hamm

Physical Therapy, University of Southern California

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