Bandages and dressings are two different things. A dressing is a material which is in direct contact with a wound, whereas a bandage is a material placed or wrapped over top of the dressing to keep it in place and absorb fluids. A wound is any damage to the body that cuts, punctures, tears or otherwise damages the skin. That could include open wounds like lacerations or closed wounds like bruises.
A dressing can have multiple purposes to keep in mind, although not all of the following apply to any given dressing. These purposes include:
- The maintenance of high humidity where the dressing meets the wound. A dry environment can cause dehydration and cell death at the wound site. A moist environment causes wounds to heal three to five times more quickly, and also less painfully
- The removal of excess fluids coming from the wound, including blood
- The movement of air around the wound
- The provision of thermal insulation
- Impermeability to bacteria. Infection, local or systemic, can delay or impede healing. The most common complication to would healing is infection, and hemorrhage is the most serious.
- Freedom from particles and toxic wound contaminants, so a dressing which sheds particles or fibres into the wound would not be very suitable.
- Removal without causing trauma (such as by tearing) since trauma will worsen the wound and delay healing.