An apparatus for promoting the healing of an exuding wound includes a wound cover for defining a reservoir over a wound in which a negative pressure may be maintained. The cover may form a substantially fluid-tight seal around the wound and permit fluid communication between the reservoir and a vacuum source suitable for providing an appropriate negative pressure to the reservoir to stimulate healing of the wound. A wound filler positioned between the wound and the wound cover includes a fibrous material treated with a surface modification additive.
