Case Series: Assessing Wound Healing Potential Through Use of Skin Perfusion Pressure

This article discusses the use of laser Doppler to assess wound healing status and to determine if compression therapy could be used in patients who are compromised by pathologies other than venous-related and/or lymph-related congestion.

Diabetes affects approximately 8% of the United States population,¹ with annual estimated direct and indirect medical costs of $174 billion. A portion of the medical costs are related to wound care treatment, which is estimated at approximately $4,600 per ulcer event.² Approximately 2.5% of patients living with diabetes develop ulcers annually.³ Patients living with diabetes and foot ulcers have an estimated 15% risk of amputation.⁴ Furthermore, diabetes is the leading cause of non-traumatic limb amputation.¹ One factor that contributes to reduced wound healing potential (and thus risk of amputation) is a lack of sufficient blood supply, which can be reflected in the diagnosis of peripheral artery disease (PAD). The prevalence of PAD has been documented to be twice as high in patients living with diabetes compared to controls,⁵ with approximately 50% of patients living with a diabetic foot ulcer also living with comorbid PAD.⁶

Patients are evaluated for PAD via ultrasound (U/S) Doppler using the ankle-brachial index (ABI). ABI is used to determine the integrity of arterial flow in the distal lower extremity. An ABI of < 0.9 mmHg suggests a patient has PAD and may not be eligible for compression therapy. An ABI of < 0.6 mmHg prohibits use of compression therapy in most cases. Compression therapy has the potential to assist in wound healing, although it is contraindicated for arterial compromise. ABI as determined by ultrasound Doppler is used to determine the integrity of arterial flow in the distal lower extremity and, thus, the appropriateness of compression therapy. However, ABI has been found to misdiagnose PAD or underdiagnose disease severity in patients living with diabetes.⁷ Laser Doppler has been suggested to be used as a standard for classifying severity of PAD;^8,9 it can be used as an objective method for predicting wound healing status.⁸ Further, recent evidence suggests compression with a four-layer dressing does not impact blood flow as measured using laser Doppler.¹⁰ This article will discuss the use of laser Doppler to assess wound healing status and to determine if compression therapy could be used in patients who are compromised by pathologies other than venous-related and/or lymph-related congestion. 

Methods & Participants

To be included in this case series design, study participants had to undergo a laser Doppler study, and an arterial Doppler U/S study was performed. Participants had to have an ABI of < 0.9 mmHg and/or noncompressible vessels as per U/S study, but > 30 mmHg as per laser Doppler study. Participants had to also be living with an integumentary wound that was treated with compression and have chart reference to pre- and post-compression treatment measurements of wound surface area. Participants were excluded if they lived with a venous-only or lymph-only wound without arterial involvement. Following inclusion/exclusion criteria, a total of 15 wounds (on seven patients) were included (see Figure 1 at right). 

Instrumentation

Laser Doppler – skin perfusion pressure (SPP) as measured by laser Doppler (SensiLase System, Vasamed Inc., Eden Prairie, MN) was used to assess microcirculation using reactive hyperemia to determine critical limb ischemia (see Figure 2 on page 28). 

Ultrasound Doppler – arterial Doppler study used to determine ABI and/or compressibility of vessels.

Compression Dressing – Chosen by individual wound care specialists, which included one of the following: Medigrip^TM (Medline Industries Inc., Mundelein, IL), Fourflex,^® (Medline Industries Inc.), PROFORE (Smith & Nephew, Fort Worth, TX), and/or Unna’s Boot.

Results

Participants averaged 73.6 years ± 12.0 years, 91.4 kg ± 30.9 kg, and 1.7 m ± 0.1 m. There were three females and four males living with a total of 15 wounds. All 15 wounds showed improved wound surface area with seven of the 15 wounds demonstrating complete closure (see Table 1 below).  

Discussion

The purpose of this case series is to show the use of laser Doppler to assess wound healing status and to determine if compression therapy could be used in patients compromised by pathologies other than venous-related and/or lymph-related congestion. Current standard of care indicates patients experiencing arterial compromise are not typically candidates for any form of compression. The inference from our preliminary findings corroborates similar work¹¹ suggesting compression might be indicated in mixed clinical presentations where edema is present, further complicating an already compromised arterial system.¹⁰ Based on the results of this case series of 15 wounds in seven patients (all of whom had mixed etiology, including arterial compromise), compression seems to have contributed to wound healing and did not lead to adverse effects. This suggests compression may be a reasonable treatment option in patients demonstrating wound healing potential via laser Doppler study, but who live with a PAD diagnosis.   

In this case series, an SPP of 30 mmHg was used as the cutoff point to determine if compression was an acceptable treatment option, as SPP < 30 mmHg is indicative of critical limb ischemia.  Wound healing potential has been demonstrated to drop to 50% when SPP drops to 25 mmHg.¹² 

All seven patients, in addition to their comprehensive treatment, received a form of compression secondary to their “positive” SPP results. The clinical decision to compress patients predicated on their SPP likely aided in the observed wound closure, despite mixed etiology and without adverse effects. Previous research suggests wound healing can occur in patients with SPP of > 30 mmHg.¹² Additionally, as previously published, SPP is a sensitive, specific measurement of wound healing potential.¹² Furthermore, statistical regression suggests SPP can be used independently to predict wound healing.⁸

In conjunction with previous findings,^10-12 the results of this study suggest patients deemed ineligible for compression via U/S Doppler study may actually be good candidates for compression treatment if laser Doppler/SPP is used as an adjunct assessment tool to determine wound healing status. Therefore, wound care clinicians may want to consider augmenting the evaluation of wound healing potential with laser Doppler to assess SPP. It is important to note that not all compression systems are identical and that it may not be appropriate to use compression in patients experiencing marginal perfusion. Also, speculating on compression use in patients with borderline SPP is outside of the scope of this case series.

Additionally, the future use of laser Doppler/SPP in determining wound healing potential in patients is dependent on the collaboration between researchers and wound care specialists. This collaboration will continue to document the efficacy and effectiveness of laser Doppler/SPP to evaluate the eligibility for compression treatment. This may facilitate wound closure, which can decrease the long-term financial burden incurred with chronic wound management. 

Nicole J. Chimera is the corresponding author and is on staff in the athletic training department at Daemen College, Amherst, NY. She may be reached at nchimera@daemen.edu. Corstiaan Brass is on staff at the Center for Skin Integrity, Cheektowaga, NY. Michael Brogan is on staff in the physical therapy department at Daemen College.

Editor’s Note: The compression systems used in this study were determined by wound clinic staff members considering a variety of treatment choices based on patient status. Patients involved were those with high enough SPP to suggest the potential for wound healing.

References

1. Centers for Disease Control and Prevention. 2011 National Diabetes Fact Sheet. Accessed online: www.cdc.gov/diabetes/pubs/pdf/ndfs_2011.pdf

2. Holzer SE, Camerota A, Martens L, Cuerdon T, Crystal-Peters J, Zagari M. Costs and duration of care for lower extremity ulcers in patients with diabetes. Clin Ther. 1998;20(1):169-81.

3. Smith DM, Weinberger M, Katz BP. Predicting nonelective hospitalization: a model based on risk factors associated with diabetes mellitus. J Gen Intern Med. 1987;2(3):168-73.

4. Ramsey SD, Newton K, Blough D, et al. Incidence, outcomes, and cost of foot ulcers in patients with diabetes. Diabetes Care. 1999;22(3):382-7.

5. Gregg EW, Sorlie P, Paulose-Ram R, et al. Prevalence of lower-extremity disease in the US adult population >=40 years of age with and without diabetes: 1999-2000 national health and nutrition examination survey. Diabetes Care. 2004;27(7):1591-1597.

6. Prompers L, Huijberts M, Apelqvist J, et al. High prevalence of ischaemia, infection and serious comorbidity in patients with diabetic foot disease in Europe. Baseline results from the Eurodiale study. Diabetologia. 2007;50(1):18-25. Epub 2006 Nov 9.

7. Aerden D, Massaad D, von Kemp K, et al. The ankle-brachial index and the diabetic foot: a troublesome marriage. Ann Vasc Surg. 2011;25(6):770-77.

8. Yamada T, Ohta T, Ishibashi H, et al. Clinical reliability and utility of skin perfusion pressure measurement in ischemic limbs-comparison with other noninvasive diagnostic methods. J Vasc Surg. 2008;47(2):318-23.

9. Kondo Y, Muto A, Dardik A, Nishibe M, Nishibe T. Laser Doppler skin perfusion pressure in the diagnosis of limb ischemia in patients with diabetes mellitus and/or hemodialysis. Int Angiol. 2007;26(3):258-61.

10. Boggs R. The Effects of Profore Multilayer Compression Bandaging System on Skin Perfusion Pressure in Healthy Adults. Conference proceedings, Combined Sections Meeting of American Physical Therapy Association. Las Vegas, NV, February, 2014.

11. Wu SC, Crews RT, Najafi B, Slone-Rivera N, Minder JL, Andersen CA. Safety and efficacy of mild compression (18-25 mm Hg) therapy in patients with diabetes and lower extremity edema. J Diabetes Sci Technol. 2012;6(3):641-47.

12. Castronuovo Jr. JJ, Adera HM, Smiell JM, Price RM. Skin perfusion pressure measurement is valuable in the diagnosis of critical limb ischemia. J Vasc Surg. 1997;26(4):629-37.