Zinc Paste Bandages

The medicinal properties of zinc in the form of calamine were documented more than 3,000 years ago in ancient Ayurvedic manuscripts (43). As well as being beneficial in wound healing, it provides effective antimicrobial action. Many of the biochemical and molecular events in wound repair can be expedited by adding supplementary zinc ions through up-regulation of zinc metalloenzymes. Furthermore, defects in the expression of zincfinger transcription factors in mRNA coding of growth factors is consistent with impaired wound healing. Evidence for the role of zinc in repair is demonstrated by zinc metalloenzymes (e.g. alkaline phosphatase). Alkaline phosphatase is a sensitive marker for fine dermal blood vessels and early stages of angiogenesis associated with increased inflammatory activity and tissue proliferation (43).

 

Zinc oxide has been found to be as effective as an enzymatic topical debriding agent in the treatment of pressure ulcers. In diabetic foot ulcers, a zinc oxide-medicated occlusive dressing was significantly more effective in debridement vs autodebridment using a standard hydrocolloid occlusive dressing. Zinc paste bandages or Unna boot, composed of open wove cotton gauze impregnated with zinc oxide paste remains the standard treatments for leg ulcers. Unna boot provides a protective barrier and anti-inflammatory benefit to varicose eczema.

 

Zinc itself may occasionally cause burning, stinging, itching, and tingling when applied to inflamed tissues. Hypersensitivity to topical zinc oxide is rare and is most commonly associated with the dressings excipients. Zinc paste bandages must be applied loosely and lightly and the bandage covered by a retention or a compression bandage if the arterial circulation is adequate. Paste bandages can be left in place for up to a week for treatment of ulcers and up to 2 weeks if treating the skin alone (43).

 

Evidence: In a double-blind, placebo-controlled trial, zinc oxide promoted healing of leg ulcers. A three-armed randomized controlled trial involving 113 venous leg ulcer patients compared a zinc paste bandage with a zinc oxide-medicated stocking and a calcium alginate dressing. The zinc products and alginate dressing were applied in conjunction with compression bandages. The ulcers healed significantly faster in patients treated with the zinc paste bandage compared with the zinc stocking and the alginate dressing (43). 

 

 

 

 

 

 

 

 

 

 

Gauze

Using gauze to dress and bandage wounds was firmly established by the fifth century BC and is still used today. ‘Gauze’ represents woven gauze (100% natural cotton cloth) that we are familiar with. Non-woven gauze refers to more modern, synthetic dressings made of rayon or synthetic fibre blends. Woven gauze is problematic in dressing and packing wounds as it sheds fibres when cut and may leave debris in the wound bed on removal. It tends to stick to the wound, resulting in trauma on removal as it quickly dries out the wound, becoming trapped within the eschar (45).

 

Until recently, this was considered advantageous as a dry wound was considered optimal for healing and the removal of the embedded dry eschar was seen as a form of physical debridement. The perception that a wound healed best under dry conditions persisted from the Hippocrates until relatively recent research promoted maintaining a moist wound environment. Gauze strips soaked in antibiotics such as EUSOL, proflavin or chlorhexidine were used to pack wounds to prevent closure and promote granulation from the wound base. This was later changed to saline soaked gauze because using antibiotics this way was thought to be cytotoxic. Saline was employed as a hypertonic solution but quickly dried out, resulting in painful removal. Today, woven gauze is seen as a ‘wet to dry’ dressing and is used in various wound care strategies (45).

 

Despite its non-selective mode of physical debridement, trauma to the wound bed and pain, it is still the most utilised wound dressing in the world (45). It is also used as a vehicle for antimicrobial agents but has complications such as degradation or inactivation of the antimicrobial agent upon exposure to high protein levels within wound fluid and lateral bacterial migration into the wound bed within the moist environment. Factors such as cost, education and the ability to follow best practise may account for continued use of this ancient product, apparently surpassed by modern dressings. Although gauze is commonly used, more appropriate dressings have been available for years. These dressings employ many technological advancements and exhibit qualities considered to be essential in the ‘perfect’ wound dressing. Although the perfect dressing is yet to be developed, wound dressings have evolved from simple, impregnated gauzes to being ‘smart’ (45).  

 

Cotton Wool

Cotton wool was traditionally used as a primary dressing or to clean wounds, which can cause trauma to tissues and shed fibres in the wound bed, creating an opportunity for infections. This greatly limits the use of cotton wool for the mentioned roles, however its used in dressing pads or wadding as a secondary dressing. Cotton gauze is still used in some countries for “wet to dry” debridement. It’s then ripped out. It’s proven to be a successful debriding method but isn’t used in UK due to the associated pain (gauze is soaked in saline, placed in wound and allowed to dry). (35)

 

Tulle Dressings

Examples include jelonet. These are often cheap, sheets of gauze impregnated with various quantities of paraffin. Antiseptics or antibiotics can also be added. It’s only suitable for superficial wounds and require frequent changing to prevent adherence, particularly as paraffin is hydrophobic and cannot be freed by irrigation once stuck to a wound bed (35).

 

 

 

 

 

 

 

 

 

 

 

 

Sugar Paste

This is useful for malodorous and colonised wounds as sugar has an osmotic effect on bacteria and “pulls” fluid out of the cell; killing it. Odour is reduced upon bacterias removal. It appears to promote autolysis and is cheap, but very messy. Some pastes contain iodine or hydrogen peroxide and come as thick or thin pastes. They are difficult to obtain and largely unresearched (35).