An occlusive dressing is an air- and water-tight trauma dressing used in first aid

First aid

First aid is the provision of initial care for an illness or injury. It is usually performed by non-expert, but trained personnel to a sick or injured person until definitive medical treatment can be accessed. Certain self-limiting illnesses or minor injuries may not require further medical care...

. These dressings are generally made with a waxy coating so as to provide a total seal, and as a result do not have the absorbent properties of gauze

Gauze

Gauze is a thin, translucent fabric with a loose open weave.-Uses and types:Gauze was originally made of silk and was used for clothing. It is now used for many different things, including gauze sponges for medical purposes. When used as a medical dressing, gauze is generally made of cotton...

 pads. They are typically used to treat open, or "sucking," chest wounds (pneumothorax

Pneumothorax

Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...

) to alleviate or prevent a tension pneumothorax (a serious complication of a simple pneumothorax). They are also used in conjunction with a moist sterile dressing for intestinal evisceration

Evisceration

An evisceration is the removal of the eye's contents, leaving the scleral shell and extraocular muscles intact. The procedure is usually performed to reduce pain or improve cosmesis in a blind eye, as in cases of endophthalmitis unresponsive to antibiotics...

.

Occlusive dressings come in various forms, including Vaseline Gauze, which sticks to the skin surrounding the wound using Vaseline.

They can also be used to enhance the penetration and absorption of topically-applied medications, such as ointments and creams

Cream (pharmaceutical)

A cream is a topical preparation usually for application to the skin. Creams for application to mucus membranes such as those of the rectum or vagina are also used. Creams may be considered pharmaceutical products as even cosmetic creams are based on techniques developed by pharmacy and...

. Furthermore, they may be used in in vivo

In vivo

In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...

 acute toxicity tests of dermal irritation and sensitization. The test animal is shaved and the test material is applied to the skin and wrapped in an occlusive material. The skin is then exposed after 23 hours and an assessment for redness and edema

Edema

Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

is made. This assessment is repeated 48 hours later.