Tourniquet assemblies and systems, and methods for controlling tourniquets

A method of controlling a tourniquet comprising the steps of:

• (a) providing an inflatable tourniquet on a limb together with a proximal strain gauge positioned on the limb proximally of the tourniquet and a distal strain gauge positioned on the limb distally of the tourniquet, wherein the proximal and distal strain gauges provide respective output signals indicative of volumetric changes in the limb proximally of and distally of the tourniquet, respectively;
• (b) inflating the tourniquet to a working pressure which exceeds the limb occlusion pressure (LOP) of said body part, such that the distal strain gauge output signal is indicative of a constant volume;
• (c) determining, from the proximal strain gauge output, a characteristic of the time-varying volumetric changes in the proximal limb volume;
• and
• (d) responsive to a change in said characteristic indicative of a reduction in the time-varying volumetric changes in the proximal limb volume, reducing the working pressure in the tourniquet by an amount which reduces pressure on the limb while remaining above the limb occlusion pressure.