A medical dressing configured to be applied to a chest wound, the dressing including: a flexible main membrane including a front surface configured to face a chest of a patient and a back surface opposite to the front surface, wherein the flexible main membrane includes an opening； an adhesive layer on the front surface of the main membrane wherein the adhesive layer extends entirely around the opening； a flexible sealing membrane entirely covering the opening of the flexible main and overlapping at least a portion of the main membrane； an annular array of joints sandwiched between the sealing membrane and the main membrane, wherein the array of joints extends around the opening； and vent passages sandwiched between the main membrane and the sealing membrane, wherein vent passages each extend between an adjacent pair of the joints and defines an air passage from the opening and to an outer edge of the sealing membrane.
