Limb blood flow in the presence of a tourniquet.

There is little accurate data on the blood flow to a limb distal to the site of application of a tourniquet. This has been studied in Rhesus monkeys with 50 mu diameter microspheres labelled with 51Cr and by the washout of 22Na injected into the tissues. One limb was exsanguinated and the circulation occluded with a pneumatic tourniquet and the opposite limb used as a control. The results show that blood flow to the occluded limb is less than 1 per cent of the flow to the control limb. It is unlikely that this relieves the ischaemia in any way as has been suggested.