2. Justification Many studies have shown that both tourniquet pressure and time should be minimised to reduce the risk of tourniquet related injuries and post operative complaints. As the purpose of the tourniquet is to maintain a bloodless surgical field, in theory the minimum cuff pressure required to occlude arterial flow (the 'Limb Occlusion Pressure' or LOP), plus a safety margin to allow for changing conditions during the procedure, should be used. In practice, most surgeons use a standard pressure based on experience, or based on an indirect measurement of systolic blood pressure.