Modern wound care clinicians have witnessed the development of a bewildering array of new technologies, many of which have emerged as a result of the failings of previous products. One of the more successful recent advances has been the introduction of Hydrofiber® Technology. Hydrofibers are one of the most widely used modern wound care dressings and this article examines their qualities and the evidence for their efficacy.

INTRODUCTION
In the past many different materials have been used in the treatment of wounds, ranging from grease-soaked bandages to what can best be described as 'sophisticated' cloths or gauzes. Traditionally wound care was the remit of surgeons or doctors but the specialty has now expanded to include nurses and other healthcare professionals. This increasingly multidisciplinary approach has been aided by the evolution of other clinical areas such as endocrinology and diabetes and treatment options have become increasingly sophisticated.

One of the most influential figures in the evolution of wound treatment was George Winter[1]. Up until the 1960s, traditional practice dictated that clinicians use gauze to 'soak up' any wound fluid then allow the wound to dry out, scab over and ultimately heal. That was until Winter discovered that keeping the wound moist led to faster and better healing. As a result of Winter's work researchers and clinicians in the 1970s[2] began to develop newer dressings out of plastics, with the first film dressings utilising polyurethane technology[3]. During the 1980s, a better understanding of the limitations of film dressings led to the development of alternative technologies, such as alginate and hydrocolloid dressings, with each new product building on the developments that had gone before[4]. In the 1990s Hydrofiber® Technology was introduced leading to significant changes in practice.


HYDROFIBERS
A Hydrofiber is defined as a soft, sterile, non-woven pad or ribbon dressing composed of sodium carboxymethylcellulose, which is incorporated in the form of a fleece held together by a needle-bonding process. This conformable material can absorb a large amount of wound fluid, such as exudate with bacteria. This is then transformed into a soft gel, which creates a moist environment to support the body's healing process. The gel also aids the removal of non-viable tissue from the wound (autolytic debridement), without damaging newly formed tissue. Hydrofibers are versatile and can be incorporated into a variety of dressing formats[5].

Hydrofibers are neither hydrocolloids nor alginates, but a separate category incorporating the benefits of both, while also addressing their weaknesses (eg cohesive gelling, aggressive adhesion etc). As the term Hydrofiber has been trademarked, similar dressings cannot refer to themselves as Hydrofibers and as such this category may become renamed as it expands. However, since all of the pioneering work in this category has so far been driven by Hydrofiber Technology, Hydrofibers will be the focus of this review.

The first Hydrofiber dressing to be launched was Aquacel® (ConvaTec) in 1997[6]. By the mid-2000s new formulations were introduced for different clinical situations[7] and these now include the addition of antimicrobial ionic silver, or the use of Hydrofiber as a specific layer in composite dressings. Hydrofiber dressings also come in a variety of formats for different wound types and situations, for example Aquacel Hydrofiber ribbon can be used in deep cavity wounds. Different shapes and sizes of dressings are also produced for specific anatomical areas.


BRANDS
The main brands of Hydrofiber dressing are Aquacel, Aquacel Ag and Versiva® XC™ (ConvaTec).
 
Aquacel Ag is a silver-impregnated antimicrobial dressing that contains 12mg of silver per 10 x 10cm² of dressing[8]. Like any Hydrofiber it absorbs exudate to form a soft, hydrophilic, gas permeable gel[8] but also provides a barrier to bacterial penetration and helps to reduce infection[9] through a sustained release of silver ions, which can last for up to 14 days[10].

Versiva XC has an absorbent core consisting of a layer of sodium carboxymethylcellulose fibres placed upon a thin sheet of polyurethane foam/film laminate. The wound contact surface of the dressing is coated with a perforated layer of a hydrocolloid adhesive that extends to the outer margins of the dressing[8]. Versiva XC traps wound fluid and prevents lateral leakage or backflow into the wound, even under compression[11]. The outer foam/film layer is permeable to moisture vapour, which further enhances the fluid-handling properties of the dressing, whilst providing an effective bacterial/viral barrier[12]. Versiva XC is manufactured to be easy to remove without causing pain or trauma and leaves minimal residue on the wound surface[13].