The present invention relates to wound dressings for use in cases of a patient suffering a penetrating chest trauma. The wound dressing comprises a base layer having a lower surface facing the wound and an upper surface facing away from the wound, and an aperture therethrough for locating over the wound, and a top layer extending over the aperture and at least a part of the upper surface. The base layer is connected to the top layer such that the wound dressing can transition from an open configuration in which the aperture and an area external to the wound dressing are in fluid communication via at least one opening at a perimeter between the base layer and the top layer, to a closed configuration in which the top layer forms a seal over the aperture.
