Man has always tried to improve the natural process of healing of ulcerative wounds.
Indeed right from the times of the ancient Greeks and Egyptians, solutions of water and salt, milk, wine or vinegar have been used as detergents to clean wounds, while leaves, algae or sand have been used to encourage haemostasis.
The treatment of skin wounds has for centuries been limited to simple dressing, mainly consisting of linen or cotton bandages, impregnated with resins or honey.
Wound cavities were filled with natural moss, soaked in wine or vinegar.
The edges of the wounds were held together by thin bones or narrow strips of fabric soaked in glue.
Galeno (129-199 a.C.) considered that the clinical signs of infection, such as, for example, pustulant secretions, were positive and an aim to be pursued.
In fact he believed that putting the wound in conditions where it could develop infection was positive in that this caused the formation of pus which he believed was fundamental for obtain good healing (pus bonum et laudabile).

For a long time this theory was the only method of viewing the problem up until the advent, in the eighteenth century, of antibiotics or when, thanks to the work of Pasteur and Lister, mortality associated with infected wounds was reduced precisely because of the introduction of antiseptics and antibiotics.
During the First and Second World War the greatest developments took place in the field of dressing.
A simple gauze soaked in disinfectant solutions, particularly sodium hypochlorite (Milton and Dakin solution) was the treatment of choice on the battlefield up until the Second World War when penicillin became available on a large scale.

The true revolution took place, however, in 1962, when Winter published his work on acute superficial wounds induced on two domestic pigs.
(Winter, G.D. - Formation of the scab and the rate of epithelialization of superficial wounds in the skin of the young domestic pig. - Nature 1962; 193: 4812, 293-294).
By covering a wound with a film of occlusive material (polythene) below this Winter obtained a damp environment capable of guaranteeing re-epithelisation which was twice as fast as the healing of a wound left to dry in the air.
This study, which was incomplete in certain aspects (involvement of non-standard animal model, acute and non-chronic superficial wounds) nevertheless opened the way for a new method of wound management: healing within a damp environment.

The idea that the fibrinous eschar, a physiological product of the coagulation process, was not a positive aspect at all, began to become clear, and that in reality it actually creates a mechanical barrier for the newly formed epidermal cells which migrate from the edge to the bed of the ulcer, thus prolonging healing time.
Up until then in fact a dry wound environment was considered essential, particularly in order to prevent the colonisation of bacteria and consequent infection.
This impetus in the 1960s led to a lot of attention being paid to observing the process of wound healing.

This resulted in the concept of advanced dressings in contrast with traditional types of dressing, given this name because they are associated with old traditions for wound protection.
The purpose of the traditional dressing was to cover and hide the wound, and to absorb excess exudate; for this reason treatment was basically the same for all wound types.
These dressings often consisted of a gauze made of cotton or fabric which, once brought into contact with the wound, dried out absorbing the granulation tissue which had just been formed; tenacious adhesion to the bed of the ulcer at the time of changing dressing caused trauma, pain and, often bleeding.
With Winter the concept of interaction between the dressing and the ulcerative wound began to become clear with the ultimate aim of creating an environment capable of accelerating the process of tissue repair.

Table 1 - Comparison between traditional and advanced dressings

The first advanced dressings which arose directly from Winter's experiment were films having different chemical compositions (polythene or polyurethane) but all linked by the same characteristics: selectively adhering to the skin around the wound but not to the bed of the wound, allowing the creation of a damp micro environment below the dressing, making gaseous exchange possible with the exterior and thus allowing maceration of the tissues.
The danger of bacterial colonisation was also reduced by these dressings, by guaranteeing impermeability to liquids and bacteria.
The limited drying out of the ulcer and the maintenance of a damp layer above the nerve endings finally meant that some patients felt less pain.

Thus the first films came into being. They were initially used as a surgical bandages for incisions and it was only at the end of the 1970s that they were used to treat ulcers.
Semipermeable films consist of sheets of polymers or copolymers of polythene or polyurethane covered on the side in contact with the wound by a hydrophilic adhesive for fixing.
They have the characteristic of being semi-occlusive dressings, i.e. they allow minimum gaseous exchange between the damp environment underneath the dressing and the external environment, but they prevent liquids and bacteria coming from the exterior from entering.
They are transparent because they allow the wound to be inspected, and can therefore remain in place for several days.
The hydrophilic adhesive is inactivated by humidity and by the exudate from the ulcers, thus guaranteeing non-adherence to the bed of the wound and therefore encouraging non-traumatic removal which does not disturb the newly formed granulation tissue and does not cause pain; instead it sticks to the healthy skin around the wound, securing it in place.
However this type of dressing does have limitations: the poor capacity to absorb fluids from the ulcer and, in dressings using adhesive, the aggressiveness of the products used as glues on the skin around the wound.

In order to overcome the limitations of these initial "new" dressings, from the 80’s to date there has been great excitement within the sector; more specifically dressings have been researched and designed which, at least theoretically, should offer the following characteristics:

• maintaining a damp wound environment
• avoiding maceration due to excessive humidity
• being impermeable to penetration of liquids from the exterior
• allowing gaseous exchange of carbon dioxide, oxygen and water vapour with the environment external to the wound
• guaranteeing thermal insulation for the wound
• making sure, as far as possible, that it does not contain toxic elements, that it has a low probability of creating allergies and above all that it is sterile
• having high powers of absorption in relation to the exudate and holding it, possibly, even under compression
• not leaving residues on the bed of the ulcer
• acting as a barrier against the entry of micro-organisms
• not sticking to the ulcer
• providing a mechanical barrier for the wound, protecting the wound from possible trauma
• guaranteeing the patient's comfort and avoiding pain
• adapting to different anatomical areas
• being simple to use and safe to use
• allowing it to remain in position for a sufficiently long period
• allowing the progress of healing to be monitored without removing this dressing

Numerous types of dressing have been produced with just as many variations:

HYDROCOLLOIDS
These types of dressing consist of mixtures of natural or synthetic polymers suspended in microgranular form in an adhesive matrix and covered externally by a polyurethane film.
They are capable of interacting with the wound in a slow way undergoing a transformation when they transfer their own components to the wound; in this way they can stick to the healthy skin without adhering to the bed of the wound.
Thanks to their characteristics they manage to absorb exudate of up to ten times their own weight.
They are often also considered to be occlusive dressings in the absolute sense, but in reality they have minimum permeability because of the external polyurethane film which does, however, allow gaseous exchange with the external environment.

ALGINATES
These are types of dressing based on calcium and/or sodium salts of alginic acid obtained from marine algae.
The latter can in turn have different characteristics depending on the percentage composition of glucoronic acid and mannuronic acid thus obtaining a range of different types of alginates.
Their special characteristic is their high absorbency, even if they are not capable of holding the liquid absorbed, in that they produce a gel which makes their removal particularly non-traumatic.
They are also characterised by a certain hemostatic capacity deriving from the calcium alginate which makes them suitable for dressing for haemorrhagic wounds.

HYDROGELS
These are types of dressing which have a high percentage of water (over 40 per cent) together with hydrophilic polymers or copolymers of various kinds (polyvinylpyrrolidine, polyacrylamide, polyethylene oxide).
Other components are a gelling agent, present in a minimum percentage as starch or carboxy methylcellulose, and with a humectant agent acting as a preservative, generally propylene glycol.
Depending on their composition, hydrogels may be presented in various forms: as an amorphous gel or stratified into three-dimensional layers or in the form of impregnated gauzes.
The presence of high quantities of water keeps the wound hydrated, making them the optimum choice in the management of dry wounds and those with scabs.
The amorphous gel reduces its viscosity while it remains in place until it liquefies.

FOAMS
These types of dressing are derived naturally from films, and have the advantage of being able to absorb the exudate which films cannot do.
They consist of polymers in solution, transformed into foam by means of an industrial process which creates a matrix with cells capable of absorbing fluids.
The dimensions of these cells can be checked during the manufacturing process, obtaining foams with various characteristics.
Within the extremely wide range of products available, what differentiates the different foams is their permeability, thickness and adhesive characteristics.
The dimensions of the sheets of polyurethane which constitute the dressing vary from 4-7 mm down to less than 1 mm in the super thin ones, obtaining dressings with different capacities of exudate absorption.
They can be equipped with an upper covering film which makes the dressing impermeable to liquids and bacteria; they may have a hydrophilic adhesive in the portion which comes into contact with the wound in order to avoid the use of secondary dressing for fixing.
We should also point out the wide availability of dressing shaped to suit different anatomical areas.

The table below summarises the characteristics of the dressings referred to above.

The use of advanced types of dressing in the course of the last two decades has highlighted their advantages but has also revealed some of their limitations; some types of dressing can in fact cause maceration and other types of dehydration of the ulcer.
These findings have led to the production of new types of dressing based however on previous ones (new polyurethane foams, new hydrocolloids, etc.).
In particular attempts have been made to pay attention to the interaction between the dressing and the bed of the ulcer, to its powers of absorption and to the trauma and pain caused by removing dressings.
New products have therefore been marketed, such as hydrofibres and polyurethane foams with silicone on the face which comes into contact with the wound.
So-called "biologically" active types of dressing have also been marketed (dressings based on collagen, hyaluronic acid, peptides and growth factors).
For some years now the use of larvae (maggot therapy) for the detersion of ulcers has been re introduced in clinical practice, especially in the UK and USA.
Also many types of dressing which are based on antimicrobials (with silver, with iodine) have recently been introduced and finally some types of dressing which base their activity on the modulation of metalloproteinases and other pro-inflammatory factors.

In order to conclude the section on dressing we ought to mention other alternative therapies such as VAC therapy (Negative Pressure Wound Therapy) which is based on the applying negative pressure to the bed of the ulcer.
Just this year a controlled study has been published (Wound 2004) conducted on 24 diabetic patients. Its results are encouraging even if more extensive subsequent studies are required to determine the indications and to check the real benefits of this promising alternative therapy.
There are other alternative approaches which do however require in-depth and wide-reaching studies to check the actual efficacy (hyperbaric oxygen therapy in addition to the well-known indications, electrical transcutaneous stimulation of nerves, topical oxygen therapy, ultrasound and therapies using heat, lamps, etc).

It is however essential to emphasise, right at the end of this section, that it is of primary importance to obtain a precise diagnosis before commencing any treatment and before using any particular type of dressing.
We frequently see patients for whom advanced dressings have been used where there is no indication for this or even more often no rational; a typical example is treating ischaemic ulcerative wounds for months and months which, if re-vascularisation does not take place, in most cases leads to amputation ( Figure 66) and ( Figure 67).