The apparatus comprises an inflatable sleeve 6 to be wrapped around a limb, typically a thigh, of a patient. The sleeve 6 comprises three inflatable chambers 3, 4, 5. Inflation is controlled by a pump 1 so that the distal chamber 3 is inflated first to a low pressure to act as a tourniquet, followed by inflation of the central chamber 4 to a pressure to drive fluid flow upwards, and then inflation of the proximal chamber 5 to a low pressure to act as a tourniquet and deflating both the distal 3 and central 4 chambers to produce a negative pressure gradient down-stream in the limb causing fluid to be drawn up the limb. This cycle is repeated a number of times over a period of two minutes before allowing the limb to rest for two minutes, resulting in increased mean arterial blood flow.