What are the most effective wound dressings?

It depends. Transparent film dressing is an adhesive layer that is vapor permeable but moisture resistant. It allows oxygen to pass through to the wound. It is impermeable to water and bacteria. It is adherent; applying a skin protectant to surrounding skin is advisable. It allows visualization of the wound bed, but does absorb wound exudate. 

Hydrocolloid dressings, usually used for moderately exudating wounds, are wafers made from cellulose, gelatin, pectin and elastomers. The wafer is fixed to a semipermeable sheet and applied directly to the skin.  

Hydrogel dressings are 96% water-based and were developed to provide water molecules or moisture to desiccated, dry wounds. Hydrogel dressings are dispensed in gel, impregnated gauze, or fiber-meshed sheets. They can absorb minimal exudate and conform to the shape of the wound. They do add moisture, requiring a secondary dressing. 

Calcium alginate dressings are made from seaweed. These dressings are used for wounds with moderate to heavy exudate because they can absorb 15 to 30 times their weight, but they are contraindicated with dry wounds.  

Foam dressings are a polymer material or film-coated gels. They are capable of absorbing exudate and can be used as primary or secondary dressings. Many foam dressings have silicone adhesives that are waterproof. 

Hydrofiber dressings are 100% sodium carboxymethylcellulose. These dressings are applied dry but become a gel when they come in contact with exudate. 

Polymeric membrane dressing is a hydrophilic foam dressing with a nontoxic cleanser, glycerin to help keep the dressing from adhering to the wound, starch copolymer that absorbs exudate, and a semipermeable back layer.