A long term wound dressing with a semi-permeable membrane containing a plurality of raised capillaries with internal capillary channels. A closable aperture, such as a slit, runs parallel to the capillary channels. The closable apertures open upon increased pressure caused by flushing fluid or other fluid between the dressing and the wound, allowing the fluid to drain away from the wound. The long term wound dressing may contain additional apertures for attaching flushing and drainage tubes.
