Cutoff Value of Ankle Brachial Pressure Index for Vacuum Assisted Closure Application in Diabetic Foot Ulcers

Introduction Diabetes Mellitus (DM) is a chronic disease, which is considered a global public health problem that leads to major clinical, economic, social, and quality of patient life issues (1). 15% of diabetics will develop a diabetic foot ulcer (DFU) during their lifetime, which is an exceedingly expensive and disabling complication of diabetes mellitus. (2).

Assessment of foot perfusion is a crucial step in treatment of patients with DFU. The ankle-brachial pressure index (ABPI) is a simple, quick, non-invasive tool (3). The key elements of effective DFU management are clinical awareness, appropriate blood glucose levels, regular foot exams, therapeutic footwear that fits the patient, off-loading, local wound care, and the identification and treatment of osteomyelitis and ischemia (4).

Multiple adjuvant therapies have been studied to decrease DFU healing times and amputation rates. These therapies include negative pressure wound therapy (vacuum-assisted closure), non-surgical debridement agents, oxygen therapies, human growth factors, energy based therapies, and systemic therapies(5).Cellular and/ or tissue based product (CTPs) may result in higher average number of ulcer free months and lower average number of amputations and resections compared to standard of care (SOC) alone (6).

Negative pressure wound therapy (NPWT) is a non-invasive therapy that removes fluid from wounds, prepares the wound bed for closure, reduces edema, and promotes the creation and perfusion of granulation tissue by applying regulated negative pressure using a vacuum-assisted closure (VAC) device (7). NPWT is indicated in traumatic, acute wounds, sub-acute wounds (i.e. dehisced incisions), chronic open wounds (stasis ulcers and diabetic ulcers), pressure ulcers, flaps and meshed graft (8).

We conducted this this study to verify cutoff value of ABPI at which diabetic foot ulcers get benefit from VAC application.

Methods A single-center prospective observational study had been performed. Between March 2020 and May 2021, 56 patients with DFUs underwent VAC application in the Department of Vascular Surgery. The inclusion criteria consisted of the following: the patient ≥40 years with unhealed diabetic foot ulcers belonged to grade 1 or grade 2 (in both wound and infection categories of wound, ischemia and wound infection " WIFI classification) . Patients with immunocompromised status, varicose veins, chronic venous insuffiency, foot ulcers belonged to grade 3 (in both wound and infection categories of WIFI classification) . All patients who were involved in the study gave their written consent.

The patients were subjected to history taking including history of foot ulceration, amputation, symptoms of claudication, neurologic changes, vascular surgery and medical comorbidities. The site, shape, base and margins of the ulcer had been clinically examined. The clinical manifestations of infection including erythema, warmth, swelling, pain or tenderness were searched for. Proper neurological and vascular examination had been applied to all included feet. The following investigations were done: duplex U/S on arterial system (for all patients), X-ray (in case of suspected infected collections or osteomyelitis) and CT angiography (when duplex is inconclusive).

Procedure description:

Prior to VAC application, ABPI was measured and documented with using of Bistos hi dop vascular Doppler with 8MHZ probe (Bistos Co., Ltd. Galmachi-ro, Jungwon-gu, Seongnam-si, Gyeonggi-do, Korea) and mercurial sphygmomanometer (ALPK2, 300v velcro cuff, Japan) according to the procedure described by the American College of Cardiology (ACC) and the American Heart Association (AHA) guidelines (9) and ulcer was prepared by debridement of devitalized tissue, proper hemostasis and wound irrigation with saline .

Then, length, width and depth of the ulcer were measured by metal ruler and documented. The ulcer was gently filled with foam, ensuring that the foam was slightly above the ulcer edge. The drain was placed between foam layers. The drape was sized and trimmed to cover the entire ulcer as well as about 3-5 cm of intact skin around it. The drape shouldn't be stretched or under tension. Adhesive plaster was used at edges to maintain sealing and negative suction .

The dressing drain was attached to canister tube with opening the clamp. The suction pressure was adjusted at-120 mmHg with intermittent mode. If the patient experienced bleeding despite good hemostasis or pain that was not relieved by analgesics, pressure can be reduced by 10mmHg. Power button was pressed to turn on Smith\& Nephew Renesys EZ plus NPWT device (Smith \& Nephew Medical Ltd. Hull HU3 2BN, England. The patient was informed about steps of disconnection and maximum period of disconnection 2hours /day. Patient or his/her relative was informed about causes of alarm e.g. low pressure, full canister, line blockage and low battery and how to manage them.