A dressing for covering a wound of a patient, for example in the case of a penetrating chest wound to assist the patients breathing, comprises a sheet member adapted to be adhered to the patients skin in use to provide an airtight seal around the wound. The skin-adhesion is provided by a hydrogel layer 10 on the skin-facing face of the sheet member. The sheet member defines in use a substantially enclosed space 5 above the wound. A plurality of mutually spaced-apart flutter valves formed by holes 5 in a thin film 13 overlying an upper face of a layer 12 of the sheet member permits one-way air, blood and/ or other fluid flow communication from the space 5 above the wound to the exterior of the dressing.
