Some embodiments are directed to a system 10 for the application of topical negative pressure therapy to a site 18 on the body of a mammal. Some embodiments of the system 10 comprise a piston 22 and cylinder 24 device 12 having a self-contained power source for the generation of a reduced pressure and for aspirating the site 18. Some embodiments of the system 10 comprise a dressing 14 sealably surrounding the site 18 that can be operably connected to the device 12 by a conduit means 16 to apply the reduced pressure to the site 18.