Overview

Semi-permeable films were one of the first major advances in wound management. They consist of sterile plastic sheets of polyurethane coated with hypoallergenic acrylic adhesive and are used mainly as a transparent primary wound cover. They are semi-permeable and transmit moisture vapour, but do not absorb exudate. They provide a protective environment that is impermeable to bacteria and liquids, and can stay in place for up to 7 days. They are indicated for dry, superficial wounds as a primary dressing however can be used as a secondary dressing on top of dressing pads or foam dressings in heavier exuding wounds. They can also assist with friction reduction when applied to intact skin on vulnerable areas. Caution is required when removing film dressings as the adhesive can damage the epidermal layer (66). Examples: C View, Tegaderm, Hydrofilm, and Opsite (8). Indication: Lightly exuding wounds, wounds with eschar. Pros: Highly comfortable, transparent film permits constant observation, used to protect patients at risk of minor skin damage due to shear or pressure. Cons: Fluid may accumulate leading to tissue maceration and wrinkling at adhesive contact site, no absorbency. Notes: should be avoided in infected, large heavily exuding wounds and chronic leg ulcers (8).

 

Description of System

These dressings have been used for a long time and their effects on moist wound healing were first investigated by Winter, Hinman and Maibach. Film dressings were originally made from nylon derivatives supported in an adhesive polyethylene frame which made them occlusive. The original nylon derived film dressings however, led to skin maceration, bacterial proliferation and risk of infection and therefore requiring regular changing and irrigation of the wound with saline, making them unsuitable. The original nylon dressings are also difficult to apply and tend to wrinkle on removal from their packs (8).

 

Opsite is a thin semi-permeable film made from polyurethane covered with hypoallergenic acrylic derivatives and is more porous and permeable to water vapour and gases. The films can be transparent, conform to contours such as elbows, knees and sacral areas and do not require additional taping. However, they are too thin to be packed into deep or cavity wounds and only suitable for relatively shallow wounds. Most of the existing brands differ in terms of vapour permeability, adhesiveness, conformability and extensibility (8). They are unable to cope with large amounts of exudate and may cause maceration of skin surrounding the wound bed if they are used inappropriately (8).  

 

Mechanisms Involved

The control of water vapour is dependent on the moisture and vapour transmission rate, which varies depending on the brand (Vapour transmission rates range from 300 - 800g/m2/24 hours). This way, this dressing creates a moist wound environment (66). One example of a medicated film dressing is Tegaderm™ Plus (3M), a thin polyurethane membrane coated with a layer of acrylic adhesive that contains 2% iodine in form of an iodophor. When it comes into contact with skin, the iodophor slowly releases the iodine; reducing bacterial load and protecting against infection (66).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Costs and Evidence

Several studies have concluded that Tegaderm CHG (3M Tegaderm CHG IV securement dressing)  is associated with a lower rate of major catheter‑related infections than non‑CHG dressings and that adopting Tegaderm CHG reduce bacterial numbers on the skin and reduce the bacterial load at the central venous catheter insertion site compared with standard dressings (e.g. gauze) (68). Tegaderm (Film dressing with adsorbent pad) by 3M healthcare Ltd ranges from £0.26 – £2.60 (54). It’s therefore relatively inexpensive, factoring unit costs only.