The diabetic foot is an open wound or injury that occurs mostly on the sole of the foot in about 15% of diabetic patients. These lesions usually appear in long-term diabetics and are the expression of a dual neurological and arteriopathic type of pathology. Diabetic neuropathy prevents the patient from feeling microtraumas to the foot, while diabetic arteriopathy reduces blood flow below what is sufficient to maintain the right tropism of the extremities and therefore the healing of small wounds.

The injuries of the diabetic foot are generally classified as follows (Wagner classification):

• Grade 0: No injury, the foot is not at risk
• Grade 1: Superficial ulcer
• Grade 2: Complicated ulcer
• Grade 3: Deeply complicated ulcer
• Grade 4: Local gangrene
• Grade 5: Gangrene of the entire foot

Diabetic foot ulcers, once formed, usually cause pain and tingling, especially if they concern the outside of the foot.

Negative pressure therapy plays a role in treating the diabetic foot, but the regimen of use differs from that of treatment of wounds by second intention.
In particular, a higher frequency of dressing changes is recommended.

What is necessary for the treatment of diabetic wounds:

1. A surgical toilet with excision of all infected or devitalised tissue. Therapy in depression should not be applied to infected or necrotic tissue.
2. It is best to perform the first negative pressure dressing in the operating room with a skilled surgeon.
3. Subsequent treatments should be done by a doctor or nurse who is an expert in negative pressure therapy.
4. Diabetic ulcers sometimes do bleed. In this case, an accurate haemostasis should be performed, verified by physiological solution washing, with the application of negative pressure therapy postponed for 24 hours, setting the depression at half the norm value (about 75 mmHg) for the first few days. Oscillating depression may be useful.
5. If pus is present (diabetic ulcers become infected very frequently), it is necessary to apply the therapy in depression after an accurate cleansing and change the dressing strictly every 48 hours.
6. At each change of dressing, detect if there is a bad smell; in this case, carefully redo the curettage of the ulcer.
7. Patient albumin should exceed 32 mg / dL and haemoglobin 10 g / dL.
8. It is recommended to use the dressing in depression only until healthy granulation tissue is evident. Subsequently, it is advisable to intervene with the positioning of a partial thickness graft.
9. It is usually sufficient to reduce the wound by 40-60% by changing the dressing from 10 to 16 times over a period of 2 to 3 weeks.

After surgery, wound margins are usually approximated by suturing, metal clips, glue or adhesive patches. These processes hold wound margins closed for a few days. This kind of healing is called “healing by first intention.” However, not all surgical incision are closed using these methods: if there is a risk of infection or there has been a significant loss of tissue so that the margins cannot be joined, the wounds are left open in order to allow them to heal bottom-up. This kind of healing is called “healing by second intention.” This process takes much longer than healing by first intention because the tissues that are missing or that are non-viable need to be replaced by viable cells. The open area is more extended and the consequent inflammatory reaction can become chronic. The healing may involve the formation of an eschar or scab composed of dry plasma and dead cells, and the cells of the surrounding vital tissues (fibroblasts and vascular tokens) migrate towards the center of the wound and form “granulation tissue” that is fragile and bleeds easily. Only in the last phase of healing does “re-epithelisation “occur, which is the growth of the outermost skin layer that sometimes partially retracts the wound.

For example, wounds resulting from the removal of pilonidal and fistulas, burns and other events that cause a loss of substance (such as after trauma), in which grafts and flaps are not indicated, are healed by second intention. Treating these open surgical wounds are challenging because they are large, deep, carry a high risk of infection and can produce a lot of fluid (called exudate), which is difficult to manage. The options available, in addition to absorbent dressings such as those with alginates, include the use of negative pressure therapy, which has become the most widely used form of advanced therapy for various types of wounds. The negative pressure therapy “sucks” the liquid that originates in the wound and collects it in a binder called a “canister.” This action keeps the wound dry and reduces the bacterial count. Some studies indicate that negative pressure therapy can reduce healing time by one-half to one-third compared to traditional dressings.

Venous ulcers are wounds that appear between the ankle and the knee as a result of an insufficient blood supply to the lower limbs. They are quite common and generally affect the elderly, especially women and obese people. They are generally associated with a state of venous hypertension due to chronic venous insufficiency, or thrombosis of the saphenous vein with obstruction of the return of venous blood. They start as brownish discolorations that are followed by thinning of the skin and finally by a breakage of the skin forming ulcers of different depths. These ulcers can then also get infected.

They are classified in the following order depending on the underlying venous insufficiency:

• C0: No visible or palpable signs of venous insufficiency
• C1: Telangiectasia or venous reticulum
• C2: Varicose veins
• C3: Leg oedema
• C4a: Skin alterations due to diseases of the veins (pigmentation, eczema)
• C4b: Severe skin alterations due to diseases of the veins (dermatosclerosis, white atrophy)
• C5: C4 + ulcers healed
• C6: Skin changes with active ulcers

There are different types of therapy for venous ulcers and their underlying problems. First of all, it is important to identify the type of vascular disease that is causing it. If possible, once the disease is cured, a compression dressing is applied to the ulcers and changed until the wounds have healed. The compression phase of the dressing once was carried out with pinstriped boots (Unna boot); currently it is carried out with graduated elastic compression stockings. These ulcers easily reopen once the compression is removed. Sometimes these ulcers require grafting with medium-thick skin grafts. Healing with compression, in uncomplicated cases, takes about 40 days.

Compression therapy is considered the standard of treatment for venous ulcers.

Negative pressure therapy can be used for venous ulcers, although its superiority over other types of conventional therapies, with dressings and compression, has not been fully demonstrated. There is one particular study that shows that cutaneous healing with negative pressure therapy takes less time than with compression dressings.

In cases in which it is necessary to cleanse the ulcer, such as in preparation for a skin graft, negative pressure therapy is definitely more useful than the compression dressing.

In general, negative pressure therapy requires less frequent medications, is often self-managed by the patient or caregivers and is recently preferred by doctors and patients for its provision of greater patient comfort.

Decubitus, also known as bed sores or pressure ulcers, are areas of the skin, the underlying tissues, or both, that are injured. Decubitus ulcers can be painful, are prone to infection, smell bad and can affect patients’ quality of life.
People at risk of developing decubitis ulcers include: the elderly, those who are bedridden for long periods of time, people with spinal cord injuries and sometimes people who remain seated for long periods of time in a static position. The social cost of decubitus ulcers is very high, reaching a level of 4% of public spending in some countries.
A large study of hospitalised patients revealed a prevalence of decubitus of 10.5%, reaching a level of 26% for long-term patients. Decubitus ulcers should be prevented in the first place by frequently moving patients who cannot move independently. When decubitis ulcers occur, they must be treated quickly.
Decubitus ulcers are divided into different stages in order to better define the therapies to be applied.

• Stage 1: Skin still intact with redness that does not turn white when pressed against a bone surface. The area is usually sore, solid, soft and warmer in temperature than adjacent areas.
• Stage 2: Partial thickness. There is a shallow open injury and the bottom of the wound is pinkish, without secretions. It can also present as a blood blister. No bruising is apparent. This stage is not to be confused with skin tears, patch injuries, burns or incontinence dermatitis.
• Stage 3: Full thickness. The subcutaneous fat can be seen, but bones cannot. Tendons and muscles are exposed. There might be secretions, but the depth of the wound can still be determined. There might be possible sub-processes and tunneling.
• Stage 4: Full thickness with exposure of the bones, tendon and muscles. There might be secretions and eschars. There is often subduing and tunneling.

Over the years, many useful therapies have been used to address decubitus ulcers, such as dressings, creams and weight redistribution. Only more recently has negative pressure therapy been utilised. NPWT is implemented by first debriding and cleaning the wound, then placing a back sponge in the wound under gentle suction. The liquid produced by the wound is aspirated and collected in a container. Negative pressure therapy collects high volumes of exudate, thereby reducing the frequency at which the dressings have to be changed, while also reducing the exposure of the wound to the outer environment.
Kinetic concepts such as suction-encouraged tissue regeneration, microdeformation, perfusion augmentation and removal of infection are correlated benefits.
Possible side effects are wound maceration and retention of the wound’s dressing material (sponge), which could cause infection.
While there is no scientific evidence that suggests that negative pressure dressings are indispensable for ulcer healing, this therapy is always used when it is available for its guarantee of better wound cleaning and the elimination of foul odor, which contributes to creating greater comfort for the patient.
In the span of six years, from 2001 to 2007, the health care costs for negative pressure therapy pumps have increased by 600%. Although there are less expensive systems, many secondary facilities have difficulty finding the material and medical devices necessary to perform this kind of therapeutic intervention.