MANAGEMENT OF THE DIABETIC FOOT ULCER

The development of a diabetic foot ulcer is a significant progression for the patient with diabetes. Many times, the patient is not seen by the wound care team until a diabetic foot ulcer is already present, and patient education must be provided in the midst of a great deal of other interventions. The patient may feel overwhelmed and lack the capacity to grasp all the new information. In such a case, the clinician focuses on creating a supportive relationship with the patient. Treatment goals, management strategies, and obstacles that the patient encounters are explored, and solutions that are workable for the patient are put in place.

Once a diabetic foot ulcer has developed, there are two important goals: 1) healing the existing ulcer and 2) preventing further ulcers from developing. A history of a prior diabetic foot ulcer is the greatest risk factor for developing further ulceration. The occurrence of an ulcer ranges from 30%–50% in persons who have a history of a previous ulcer (Baranoski & Ayello, 2020).

In order to achieve the goal of wound healing and complete wound closure, interventions must be started early and applied aggressively. Several interventions take place simultaneously, for example, infection control, assessing for adequate blood supply to the affected extremity, wound care, and off-loading.

It is a highly stressful time for patients and families, who can have a hard time keeping up with all that is going on, meeting new providers, the possibility of information overload, and having to make rapid decisions, plus the very real fear of losing a limb. The support of the wound care team is of paramount importance at this time, and patients will often rely on clinicians that they are most familiar with to help them understand what is happening and guide them in making decisions. Therefore, it is important that in the frenzy of activity, the clinician makes quiet time to be with the patient as an individual and to simply ask, “How are you doing?”

Diabetes Management

To achieve healing of the diabetic foot ulcer, the wound care team must concurrently address optimal diabetes control, with the primary focus on tight glycemic control and managing risk factors such as hypertension, hyperlipidemia, and smoking. A nutritional evaluation should also be performed and any nutritional deficiencies corrected.

If the patient’s footwear has not been examined previously, a footwear assessment is done at this stage. If possible, the clinician exams the footwear that the patient wears to work and when going out as well as the slippers or other footwear worn while at home. If the patient is not yet in the habit of checking their footwear, the clinician instructs them in this important step, stressing the importance of examining all footwear for the presence of foreign bodies that may cause irritation and trauma to the patient’s foot (e.g., pebbles, small pieces of glass, straight pins, small needles, even pet hairs) (McDonald, 2019).

Vascularization of the Affected Limb

An ulcer will not heal without an adequate blood supply regardless of what other interventions are put in place. Studies indicate that 30% of patients with diabetes who have lower extremity neuropathic disease also have coexisting peripheral arterial disease (PAD) (WOCN, 2022). The essential elements of a vascular assessment include:

Inspection of the skin, hair, and nails of both lower extremities, to determine if atrophic changes are present. The clinician looks for skin that is pale in color, thin, and shiny. However, the clinician is aware that the feet can be red and warm to the touch even in the presence of severe ischemia. This results from a high shunt blood flow due to autonomic neuropathy (WOCN, 2021). Also notable is a lack of hair growth on the lower extremities that is not typical for the patient, i.e., the patient may state, “I used to have a lot of hair, even on my toes, but not anymore.” Ridged toenails may also be present.

Venous refill time. Prolonged venous refill time of >20 seconds and prolonged capillary refill of >3 seconds indicates decreased perfusion to the extremity.

Palpation of lower extremity pulses (the dorsalis pedis pulse, located on the dorsal surface of the foot, and the posterior tibialis pulse, found posterior and inferior to the medial malleolus). If the clinician is unable to palpate pulses, a handheld Doppler probe is used. Diminished or absent pulses require further testing and a probable consult to a vascular specialist. However, vascular insufficiency cannot be determined solely on the absence of pulses; some people lack one or both pulses and still have normal circulation, whereas many people with vascular insufficiency have normal pulses (WOCN, 2022).

Assessment of ankle-brachial index (ABI). This is a simple, indirect test of lower extremity perfusion done by the clinician in the clinic. It is one of the most frequently used noninvasive tests of lower extremity circulation. ABI is measured by comparing pressures in the upper extremities with those in the lower extremities.

OBTAINING AN ABI

The procedure for obtaining an ABI is as follows:

  • Have the patient rest supine in a quiet, comfortable environment for about 10 minutes before starting the test.
  • Explain the procedure to the patient and begin by measuring the brachial pressures in each upper extremity using a standard blood pressure cuff that is the appropriate size for the patient, a Doppler probe, and transmission gel.
  • Place transmission gel over the pulse site and inflate the cuff to about 20–30 mm higher than the last sound heard.
  • Place the tip of the Doppler probe pointing toward the patient’s head at a 45-degree angle and slowly deflate the cuff until the first sound is detected. This is then recorded as the systolic pressure, and the procedure is then repeated in the opposite extremity.
  • Place an appropriately fitting cuff around the lower leg about 3 cm above the malleolus, and follow the same procedure as above for obtaining the pulses. In this instance the tip of the Doppler probe is at a 45-degree angle pointing toward the patient’s knee.
  • Measure the dorsalis pedis and the posterior tibialis pulses in both lower extremities.
Illustration showing steps for obtaining an ABI

(Source: National Heart, Lung, and Blood Institute.)

The ABI is calculated by dividing the higher of the dorsalis pedis or the posterior tibialis pressure for each lower extremity by the higher of the right or left upper extremity systolic pressure. An ABI reading of 1.0 is considered normal (WOCN, 2022).

However, arteries in the lower extremities can become less compressible due to diabetes, and this can result in ABI readings of >1.1–1.3. These results are abnormal and can be found in approximately one third of all patients with diabetes. Abnormal ABI results must be followed up with more extensive testing. ABI testing is done in the imaging department, where Doppler waveform patterns will be available and provide a more accurate picture of blood flow to the lower extremities.

Indications for revascularization include not only critical limb ischemia but any situation in which there is evidence of decreased or impaired circulation. It is important for the clinician to keep in mind that adequate perfusion is essential to achieve healing and to prevent or delay a future amputation. The recommendation is that all patients who present with critical limb ischemia, an existing diabetic foot ulcer, and rest pain be referred to a vascular surgeon for evaluation of arterial reconstruction (WOCN, 2022).

Although the rate of lower extremity amputations caused by infection has remained steady, the rate of amputations related to peripheral arterial disease (PAD) has decreased 10-fold in the United States over the past 10 years. This drop is accredited to the development of endovascular surgical techniques that permit arterial inflow surgery to be extended distally with fewer complications. It is reported that up to 80% of PAD can be remedied by endovascular therapy. The existence of several areas of stenosis may need a combination of angioplasty and bypass graft (Abbas & Bal, 2019). However, the drawbacks that have been noted with endovascular surgical techniques include reduced hemodynamic advantage and diminished long-term stability, compared with bypass surgery (WOCN, 2022).

The vascular status of the affected extremity must always be determined before proceeding to sharp debridement of the ulcer. Prior to performing extensive sharp debridement, a consult to the vascular surgeon may be warranted and revascularization done, if appropriate, to prevent damage to tissues that already have poor circulation (IWGDF, 2019). However, if there is wet gangrene or abscess formation in the ulcer, debridement is performed immediately, and this is usually done in surgery. Revascularization of the affected leg is attempted as soon as possible after the surgical debridement. Depending on the type of revascularization procedure, the timeframe to achieve maximum blood circulation to the foot can range from a few days to up to four weeks.

Wound Care

Wound care for diabetic foot ulcers focuses on the steps listed below to create the optimum environment for wound healing:

  • Radical and repeated debridement of the wound to remove all necrotic tissue
  • Frequent wound inspection and assessment
  • Bacterial control
  • Attention to maintaining moisture balance to optimize healing
  • Supporting epithelial edge advancement
  • Optimal dressing selection
    (WOCN, 2022)

DEBRIDEMENT

Wound and callous debridement is an essential part of diabetic foot care. For diabetic foot ulcers the gold standard for debridement is regular, local, sharp surgical debridement performed by a licensed and trained clinician using a scalpel, scissors, and/or forceps. The benefits of debridement include:

  • Removing necrotic tissue and callus
  • Clearing bacteria from the wound bed
  • Disrupting biofilm
  • Stimulating the production of growth factors
  • Reducing pressure
  • Allowing for full inspection of the underlying wound tissues
  • Facilitating drainage of secretions from the wound
  • Enhancing the effectiveness of topical preparations
  • Stimulating healing

The need for debridement must be discussed with the patient, and the clinician ensures that the patient understands the procedure before obtaining their written consent to proceed. The goal of debridement is to remove all devitalized tissue, callus, and foreign bodies down to the level where viable bleeding tissue is found. It is necessary also to debride the wound edges to permit epithelial edge advancement, which allows the epithelium to migrate across a firm, level base of granulation.

The requirement for further debridement is determined at each dressing change. Studies show that serial debridement of diabetic foot ulcers for the first four weeks of treatment has decreased the median wound area by at least 54% compared to ulcers that do not undergo debridement. Serial debridement is usually done on a weekly basis and is referred to as maintenance debridement (Bryant & Nix, 2016; Baranoski & Ayello, 2020; WOCN, 2022).

More than one type of debridement may be necessary to completely debride a diabetic foot ulcer. The type(s) of debridement used are dependent on several factors:

  • The status of arterial circulation to the extremity
  • Current medications (e.g., anti-embolic, which would increase the risk of bleeding)
  • Pain in the wound and/or surrounding tissues
  • Clinical setting (outpatient, day surgery, or inpatient)
    (Bryant & Nix, 2016; Baranoski & Ayello, 2020; WOCN, 2022)
TYPES OF DEBRIDEMENT
Name Mechanism of Action Advantages
(Mamou & Katz, 2019; Baranoski & Ayello, 2020; WOCN, 2022)
Conservative sharp debridement Loosely connected necrotic tissue is removed from the wound bed using sterile scissors or scalpel and forceps. Quick and safe way to remove dead tissue
Enzymatic debridement (collagenase) Collagenase dissolves the collagen bonds that secure necrotic tissue to the wound bed. Used when surgical debridement is not feasible, i.e., a patient on anticoagulant therapy with a risk of bleeding
Autolytic debridement A natural form of debridement, it utilizes the body’s own white blood cells to clear necrotic tissue from the wound. Safe, although slow
Biological/bio-surgical debridement (maggot therapy) Maggot larvae produce a mixture of enzymes and broad-spectrum antimicrobials to remove necrotic tissue from the wound bed. Faster than autolytic or enzymatic debridement

DRESSING SELECTION

There is no evidence to show that any one particular dressing works better for diabetic foot ulcers than other dressings. Dressing selection for diabetic foot ulcers is based on the principles of moist wound healing, management of wound drainage, ensuring a moist wound surface, and protection of the periwound area (WOCN, 2022).

When choosing a dressing, the following factors are taken into consideration:

  • What are the wound characteristics (size, depth, amount of drainage, etc.)?
  • What type of tissue is present in the wound bed?
  • What is the condition of the periwound area?
  • Can the dressing manage the amount of drainage from the wound and prevent maceration of the periwound area?
  • Will the dressing be applied to the plantar surface of the foot and will it have to fit over or between toes?
  • Is the dressing easy to apply?
  • Does the dressing remain intact and stay in place during wear time?
  • What is the frequency of dressing changes?
  • Will the dressing prevent wound trauma and pain during dressing changes?
  • What type of off-loading device will the patient be using, and will the bulk of the dressing accommodate the off-loading device?
  • Is the dressing cost effective?
    (WOCN, 2022)

General rules for selecting dressings are as follows:

  • For dry necrotic wounds, select a dressing that will rehydrate the wound and help to soften the eschar.
  • For ulcers where slough and moisture are present, choose a dressing that will control moisture and help to debride the devitalized tissue.
  • Where wound infection is present, consider an antimicrobial dressing to decrease the wound bioburden and manage wound drainage.
  • For newly forming granulation tissue in the wound, select a dressing that will protect the new tissue growth.

Dressings designed to be left in place for more than five days are not considered a good choice for treatment since diabetic foot ulcers must be inspected and assessed frequently.

SUMMARY OF WOUND DRESSINGS
Type (description) Indications Advantages
(Mamou & Katz, 2019; WOCN, 2022)
Alginates
(absorbent, made from light seaweed)
In moderately to heavily draining wounds
  • Can stay in the wound for up to 72 hours
  • Flat and rope dressings available
  • Silver-impregnated available
Hydrocolloids
(occlusive)
For autolytic debridement; to protect periwound area from trauma and drainage; not for use in heavily draining wounds
  • Simple to apply
  • Wide range of sizes and shapes
  • Conforms to wounds on most parts of the body
Hydrogels
(hydrating; donate water to the wound bed)
In shallow wounds with scant drainage
  • Cost effective
  • Easy to apply
  • Helps with pain management
  • Promotes autolytic debridement
Hydrofiber
(absorbent; made from carboxymethylcellulose)
In moderately to heavily draining wounds
  • Will not adhere to wound bed
  • Available in plain and antimicrobial forms
Foam
(absorbent, can be adhesive or nonadhesive)
In moderately to heavily draining wounds; but problematic with off-loading devices if bulky
  • Highly versatile
  • Reduces wound pain
  • Available with adhesive borders
Composite
(combination)
To provide adhesion, absorption of wound drainage, and protective barrier against bacterial infection
  • Easy to apply and remove
  • Can be used in conjunction with other topical wound therapies such as medications applied to the wound bed
Contact layer
(nonadherent layers placed directly onto wound bed)
To allow drainage to pass through to absorptive dressing above
  • Protects the wound from trauma
  • Helps maintain a moist wound environment
  • Protects newly forming granulation tissue
Antimicrobial
(cadexomer iodine, silver, honey, hydrofera blue)
Against a broad spectrum of microorganisms that cause wound infection and biofilm formation
  • Helps reduce wound odor
  • Easily removed/decreases discomfort during dressing changes
Collagen
(derived from type 1 bovine, avian, or type 3 porcine collagens)
To stabilize the chemical balance in the wound by decreasing the level of proteases, which destroy the newly forming collagen fibers in the wound bed
  • Easy to apply
  • Helps maintain a moist wound environment
  • Can be used with topical wound agents

ANTIMICROBIAL TREATMENT

Topical antimicrobial agents are frequently used in the treatment of infected diabetic foot ulcers. A short course of antimicrobial treatment is recommended to reduce the bacterial load and protect the ulcer from further contamination. Wounds treated with antimicrobials for an extended period of time may develop resistant organisms (Bryant & Nix, 2016; WOCN, 2022).

An initial two-week treatment with antimicrobials is recommended. If after two weeks the wound has improved but there are still signs of continuing infection, the wound care team may consider it clinically appropriate to continue the antimicrobial for a longer period treatment with regular reassessment. Once the signs of infection are no longer present, the antimicrobial treatment is discontinued and the wound reevaluated for the most suitable dressing to apply at this stage.

If after two weeks of antimicrobial treatment the wound shows no signs of improvement, the antimicrobial therapy is discontinued and the current treatment plan is reevaluated. The wound care team ensures that all underlying causes that impede healing have been addressed and are being adequately dealt with. The team also closely reassesses the patient’s understanding and compliance with the treatment plan (WOCN, 2022).

Topical antimicrobials regularly used in the management of diabetic foot ulcers are listed in the following table:

TOPICAL ANTIMICROBIALS
Name Description Comments
(Mamou & Katz, 2019; WOCN, 2022)
Cadexomer iodine
  • Effective against methicillin-resistant Staphylococcus aureus (MRSA)
  • Decreases bacterial load
  • Secondary dressing required
  • Patient must not be allergic to iodine
  • Not to be used in dry wounds
  • Nontoxic to fibroblasts in the wound bed
Medical-grade honey
  • Broad-spectrum antibacterial action
  • Releases anti-inflammatory substances into the wound
  • Assists with autolytic and mechanical wound debridement
Patient must not be allergic to honey, bee products, and bee stings
Silver
  • Broad-spectrum antibacterial action
  • Effective against Gram-positive and Gram-negative organisms
Efficiency depends on the rate of release of ionic silver into the wound

DRESSING CHANGES AND WOUND MONITORING

Regular monitoring of the patient’s wound and dressing is essential. For wounds that are infected, the clinician assesses the wound and changes the dressing daily. Assessment includes monitoring the status of the wound for indications that the wound is progressing, which may be characterized by the following features:

  • Decrease in wound dimensions
  • Decrease in wound drainage and wound odor
  • Formation of healthy granulation tissue
  • Open wound edges
  • Intact periwound area

Once the infection is under control, dressing changes are decreased to every two or three days. Changes in the type of dressing may also be required as the status of the wound changes.

DRESSING CHANGES AT HOME

Ideally, dressing changes are done in the wound clinic, but this is not feasible for all patients. Patients may still have to go to work or may have transportation issues. In these instances, the clinician may train the patient or a caretaker to change a dressing. The individual doing the dressing changes is instructed in clean technique and to observe for the signs and symptoms of wound deterioration, such as increased pain, increased redness, swelling, odor, or increased drainage. It is a good practice for the clinician to outline the area of cellulitis present with an indelible marker and to instruct the patient to contact the wound care team if the redness extends beyond this line.

Diabetic foot ulcers are cleaned at each dressing change and following debridement using either normal saline or a cleaning solution. Cleansing removes devitalized tissue and may also help to remove biofilms from the wound bed. (Biofilms are polymicrobial communities that contain several species of bacteria and fungi and adhere tightly to the wound bed.)

The following considerations are important when first applying a dressing and for subsequent dressing changes:

  • If possible, avoid bandaging over toes, since this may cause a tourniquet effect. When bandaging over toes is necessary, place a layer of gauze over the toes and secure it with a bandage from the metatarsal heads to a suitable point on the foot.
  • Keep dressings smooth; avoid creases and dressings that are too bulky, especially on weight-bearing surfaces of the foot.
  • Ensure that bandages are not tight at the fifth toe and the fifth metatarsal head; if necessary, trim the bandage back in these areas.
  • Do not put strong adhesive tapes on fragile skin.
  • Use a dressing that conforms to the contours of the wound bed to prevent dead space in the wound.
  • Remember that off-loading footwear needs to accommodate the dressing.
    (WOCN, 2022)

PAIN MANAGEMENT

It is now more clearly understood that many patients with diabetic foot ulcers, even those with neuropathy present, can experience wound pain and pain during dressing changes. Therefore, the clinician utilizes strategies to prevent wound trauma and minimize wound-related pain during dressing changes.

The use of soft silicone dressings and low- or nonadherent dressings are known to reduce pain during dressing changes, along with gentle and careful manipulation of the wound. If the dressing becomes attached to the wound bed and is difficult to remove, the clinician must soak it with normal saline or a wound irrigation solution and wait for several minutes before attempting to remove it (WOCN, 2022).

Treating Infection

Infection in diabetic foot ulcers can be caused by Gram-positive bacteria, Gram-negative bacteria, and anaerobic bacteria either on their own or in combination. Frequently, infections in diabetic foot ulcers are polymicrobial, meaning that several different organisms are involved.

Gram-positive bacteria associated with diabetic foot ulcer infections are:

  • Staphylococcus aureus
  • Streptococcus spp.
  • Enterococcus spp.
  • Coagulase-negative staphylococci (if this organism is positive in a superficial swab culture, it is frequently a contaminant; however, if it is obtained from a deep tissue culture or from a bone culture, it is considered an accurate finding)

Gram-negative bacteria found in diabetic foot ulcers are:

  • Enterobacteriaceae
  • Pseudomonas aeruginosa

Anaerobic organisms cultured from diabetic foot ulcers include:

  • B. fragilis
  • Peptococcus and Peptostreptococcus

Superficial infections in diabetic foot ulcers are often caused by S. aureus or beta-hemolytic streptococci. Deep soft tissue infections and osteomyelitis are usually caused by polymicrobial organisms, which include both aerobic Gram-negative bacilli and anaerobes such as anaerobic streptococci, Bacteroides fragilis group, and Clostridium. However, it has been found that Staphyloccocus aureus is an often-occurring single pathogen in these wounds (Zubair et al., 2021). Methicillin-resistant Staphylococus aureus (MRSA) is also a common finding in infected diabetic foot ulcers.

OSTEOMYELITIS

Osteomyelitis (infection of the bone) is a common finding in diabetic foot ulcers, especially in patients with moderately to severely infected ulcers. The most frequent sites for osteomyelitis are the toes and the metatarsal heads (Abbas & Bal, 2019). Osteomyelitis can be hard to diagnose in its early stages. Determining an accurate depth of a diabetic foot ulcer is essential. Ulcers that are large, deep, or in the area of a bony prominence are at considerable risk for underlying osteomyelitis. Other indicators of possible osteomyelitis are bone visible in or protruding from the ulcer (“sausage toe”).

The probe-to-bone test is a simple test that has been found useful in detecting osteomyelitis in diabetic foot ulcers. It can be done in an outpatient clinic or bedside. The clinician gently inserts a sterile probe into the wound. If the probe touches bone, the test is considered positive (Oliver & Mutluoglu, 2021) . In a study of about 250 patients with diabetic foot ulcers, researchers found that the probe-to-bone test was highly sensitive in detecting osteomyelitis (WOCN, 2022).

X-rays are the first step in confirming a diagnosis of osteomyelitis; however, early in the infection, X-rays may not be that useful since it usually takes about two weeks after the infection starts for plain X-rays to pick up changes consistent with osteomyelitis.

The Infectious Disease Society of America advises that if initial X-rays do not diagnosis osteomyelitis in the presence of clinical findings that are highly suspicious, the next step to consider is magnetic resonance imaging (MRI). A bone scan can also be done, but at this time an MRI is considered the most accurate imaging technique available in diagnosing osteomyelitis (WOCN, 2022; Baranoski & Ayello, 2020).

Bone cultures are also important in the diagnosis of osteomyelitis. To obtain an accurate diagnosis of osteomyelitis, it is recommended to surgically obtain a bone specimen since osteomyelitis is usually concentrated in a specific location, and percutaneous biopsy can miss sampling the effected bone (WOCN, 2022).

INTERVENTIONS FOR INFECTION

With the confirmation of deep infection and/or the presence of osteomyelitis, a consult to an infection control specialist is imperative. A crucial intervention at this stage is the identification of causative organisms (if that has not already been done) and the immediate initiation of antibiotic therapy.

Another consideration is the need for surgical debridement to remove all devitalized tissue from the ulcer and the drainage of any abscess that may be present. Slough and necrotic tissue provide a fertile ground for the growth and multiplication of organisms, and infection cannot be treated effectively until these tissues have been removed.

The combination of antibiotic therapy and serial wound debridement (known as conservative treatment) is frequently successful in resolving infection and allowing the ulcer to heal.

Antibiotic Therapy

Treatment normally begins with intravenous antibiotics, either in the hospital setting, outpatient clinic, or in the patient’s home, depending on the stage of the wound and the severity of the infection. Some of the most frequently used antibiotic therapies are listed in the table below.

ANTIBIOTIC THERAPIES FOR INFECTION*
Infection Type Antibiotic(s)
(Zubair et al., 2021; Barwell et al., 2017)
Streptococcus Amoxicillin, Clindamycin
Staphylococcus Flucloxacillin, Clindamycin
Anaerobic Metronidazole, Clindamycin
Gram-negative Ciprofloxacin, gentamicin, piperacillin-tazobactam
MRSA Vancomycin, daptomycin, linezolid
* This list is not all-inclusive.

Broad-spectrum antibiotic treatment is started immediately before sensitivity reports are available. Potential limb-threatening and possibly life-endangering signs and symptoms include an infection that has spread throughout the patient’s foot, wet gangrene, or the development of a hot, red, swollen foot where pain may or may not be present. In addition to antibiotic therapy, surgical evaluation and intervention are indicated if these symptoms are present.

Once the appropriate antibiotic regime has been established from culture results, antibiotic therapy is continued for at least 12 weeks. With severe limb-threatening infections, the patient will be hospitalized initially until symptoms are under control and the wound care team believes it is safe for the patient to continue antibiotic therapy on an outpatient basis or at home with the assistance of a home health nurse.

Some of the challenges of systemic therapy include the presence of peripheral arterial disease, which can diminish the effectiveness of systemic antibiotics due to inadequate localized tissue perfusion. The use of local antibiotic treatment is a means of overcoming this problem. Recent studies have shown the potential benefit of local delivery of antibiotics to the wound site using biodegradable calcium sulphate beads impregnated with antibiotics (Patil et al., 2021).

Debridement

During the course of antibiotic therapy, the diabetic foot ulcer is debrided regularly, usually on a weekly basis; however, the frequency is decided by the wound care provider or surgeon. Following each debridement, the clinician assesses the ulcer and the patient’s foot for positive signs that the infection is resolving, such as decreased redness and swelling, healthy granulation tissue in the wound bed, decreased wound drainage, and decreased wound odor. (See also “Debridement” earlier in this course.)

Advanced Wound Treatment Options

When a diabetic foot ulcer fails to heal, the wound care team carefully reevaluates the plan of care to ensure that all impediments to healing have been adequately addressed.

  • Has the patient been seen by an infection control specialist?
  • Have cultures of wound and bone been done and antibiotic therapy started?
  • Has a thorough assessment of the patient’s vascular status been completed?
  • Has tight glycemic control been achieved?
  • Is off-loading being consistently implemented?

If the underlying causes have been addressed and the wound is not responding to standard wound management interventions, then it is time for the wound team to look at advanced treatment options. The goal at this stage is to convert a chronic wound environment into one that supports wound healing. Therapies that are frequently used to achieve this goal are:

  • Negative pressure wound therapy
  • Hyperbaric oxygen therapy
  • Application of growth factors
  • Skin substitutes
  • Protease inhibitors
  • Electrical stimulation

NEGATIVE PRESSURE WOUND THERAPY (NPWT)

In NPWT, a filler dressing (commonly a porous polyurethane foam or gauze) is placed in the wound bed and secured with a cover dressing. A pump is attached to the dressing via a special seal in order to provide negative pressure, with the other end of the tubing connected to a drainage containment device. The negative pressure suction applied to the wound removes excess exudate from the wound bed, decreases edema, and decreases bioburden, all of which help to increase perfusion to the wound bed. NPWT also promotes mechanical stretch of the cells in the wound, which assists with granulation tissue formation.

Before applying NPWT, the clinician must ensure that the wound has been thoroughly debrided, that the wound is free from necrotic tissue and slough, and that the patient is on the appropriate antibiotic therapy to treat infection. Dressings are usually changed three times a week in the clinic by a clinician skilled in the use of NPWT.

NPWTi

Negative pressure wound therapy with instillation (NPWTi) allows the wound to be soaked in irrigation fluid, with saline being the preferred topical solution for the majority of wounds. The negative pressure device is programmed to facilitate cycles of fluid instillation, followed by the application of negative pressure, which removes the irrigation solution from the wound. The use of NPWTi is showing significant improvement in treating infection in a variety of chronic wounds (Baranoski & Ayello, 2020).

Recommended best practices include:

  • NPWTi as an appropriate adjunctive for the treatment of diabetic wounds
  • NPWTi as an appropriate treatment for wounds with underlying osteomyelitis
  • Discontinuing NPWTi when clinical goals are met
  • Discontinuing NPWTi within 7 days if the wound is showing no signs of progress, even after therapy modifications are put in place

In the United States, NPWTi is approved for use in acute care settings, long-term care, and skilled nursing units. However, it is not approved for home care, so once the patient is discharged, the therapy must be discontinued. In this case, even a short course of NPWTi treatment, lasting 24 hours, prior to discharge can enhance the wound environment (Kim et al., 2020).

HYPERBARIC OXYGEN THERAPY (HBOT)

HBOT has proven to reduce the number of amputations in people with diabetic foot ulcers. However, it is an expensive therapy and usually requires the patient to commit to treatments three to five days a week for six weeks or more. A significant drawback of HBOT is that many patients are unable to complete this full course of treatment, usually due to their overall poor health.

The patient is placed in a special chamber where 100% oxygen is administered under pressure. The main effect of HBOT is to increase the ability of the blood to supply oxygen to compromised tissues and thus increase wound healing. It is thought that HBOT also assists in the resolution of osteomyelitis by enhancing the oxygen supply to the bone, which increases leukocyte activity.

TOPICAL OXYGEN THERAPY

There have also been studies using topical oxygen in the treatment of DFUs. Unlike HBOT, in which the patient breathes concentrated oxygen in a high-pressure chamber, topical oxygen is applied directly to the wound bed. The most up-to-date devices utilize a miniature, lightweight, wearable oxygen delivery system that is completely noiseless and can be worn at all times.

However, conflicting results have been obtained from different studies. In their 2019 Wound Healing Interventions Guidelines, the International Working Group in the Diabetic Foot (IWGDF) did not recommend topical oxygen therapy until further studies are done (WOCN, 2022; IWGDF, 2019). Other studies related to the benefits of this newer topical oxygen systems demonstrate that this therapy does accelerate wound healing, in particular for patients with diabetic foot ulcers (Oropallo & Anderson, 2021).

GROWTH FACTORS

Platelet-derived growth factors and human epidermal growth factor have been shown to increase healing in diabetic foot ulcers. Studies demonstrate that chronic wounds such as diabetic foot ulcers have low levels of endogenous growth factors, which are essential for wound healing. Providing an external source of growth factors is believed to promote wound repair (Zubair et al., 2021). Becaplermin gel is the only growth factor currently available. It has been approved by the U.S. FDA, for treatment of nonhealing diabetic foot ulcers that are free from necrotic tissue and slough and are appropriately off-loaded.

If the wound does not show indications of healing after two weeks of growth factor therapy or if the size of the wound has not been reduced by 30% in 10 weeks of treatment, growth factor therapy is discontinued. Becaplermin gel carries a “Black Box” warning for the increased risk of cancer with the use of three tubes or more (Baranoski & Ayello, 2020).

SKIN SUBSTITUTES

Significant healing of diabetic foot ulcers has been obtained with the use of bioengineered skin substitutes (Snyder et al., 2020). Skin substitutes deliver growth factors to the wound bed, which in turn stimulates wound healing. The ulcer should be free of necrotic tissue and slough and have an adequate vascular supply. There should be no exposed tendon, bone, or muscle in the wound bed. There are dozens of commercially available bioengineered skin products on the market, and the clinician must follow the manufacturer’s instructions on the correct method of application. Usually, dressings are changed once a week with a complete assessment of the wound (Holl et al., 2021).

PROTEASE INHIBITORS

Collagen is the most common protein found in the body, and it is a vital constituent of wound healing. However, chronic wounds such as diabetic foot ulcers that fail to heal contain high levels of proteases called MMPs, which are enzymes that destroy collagen. Collagen dressings help to decrease the level of protease in the wound by forming a chemical bond with MMPs.

Collagen dressings come in several different formulations and are typically made from bovine, avian, or porcine collagen. They are nonadhesive, nonocclusive dressings that are applied directly to the wound bed and a secondary cover dressing. Dressing frequency depends on the product used, the amount of wound drainage, and the frequency of wound assessment (Baranoski & Ayello, 2020).

ELECTRICAL STIMULATION

Electrical stimulation utilizes the transfer of electrical current to the wound to assist with wound healing. Studies indicate that this therapy can produce significant wound healing. It is proposed that electrical stimulation works by increasing protein synthesis in the wound, increasing cell migration, and decreasing bacterial growth (WOCN, 2022; Baranoski & Ayello, 2020).

Electrical stimulation is applied by a physical therapist or occupational therapist who has training and experience in the use of this therapy. Direct current electrical stimulation is the form used in wound care. It is a constant, one-way current in which the voltage does not change with time. It should not be used in the presence of osteomyelitis and with patients who have electric implants such as pacemakers (Bryant & Nix, 2016).

SHOCKWAVE TREATMENT

Shockwave treatment is recommended for use with diabetic patients who are 22 years and older and who have a chronic diabetic foot ulcer (greater than 30 days). This technology utilizes energy pulses to activate wound healing (Gustaitis, 2018). The efficacy of shockwave treatment in the treatment of diabetic foot ulcers is still under investigation (Wound Source, 2020).