The actuator 1 has a pump head 20 detachably connecting to an external motor (52, fig 4) via a driven connector 23. An inlet connection 30 from the wound is attached to the pump head 20 and a fluid connector 11 in a shell 10. A liquid limit device such as a spiral tube with an inner spiral wall 33 is located in the part of the connection attached to the shell. An outlet 40 extends from the pump head. In use fluid only flows through the pump head 20 so that only the pump head 20 needs to be made of biocompatibility materials.
