tailieunhanh - The Tourniquet Manual: Principles and Practice - part 3

Vòng bít nên được làm bằng vật liệu không có thể làm nở do đó, càng nhiều càng tốt, một áp lực thậm chí còn tác dụng trong suốt vòng bít. Còng hiện đại có ốc vít mà làm cho nó không cần thiết để quấn vòng bít dài khoảng chi. Huyết áp ở bắp đùi được đo bằng một túi 18-20 cm và túi hơi lớn hơn một cách thích hợp. | The Tourniquet Manual @ @ @ The cuff should be made of non-distensible material so that as far as possible an even pressure is exerted throughout the cuff. Modern cuffs have fasteners that make it unnecessary to wrap a long cuff around the limb. Blood pressure in the thigh is measured by an 18-20-cm bag and an appropriately larger cuff. Although there is no consensus about the exact cuff size for thighs of different diameters and shapes it is important that the cuff is wider and longer than that for the arm in order to allow for the greater girth. Standard straight tourniquet cuffs are designed to fit optimally on cylindrically shaped limbs. However sometimes limbs are conical in shape especially in very muscular or obese individuals. Curved tourniquet cuffs have been designed for conical limbs and are more effective than straight cuffs at lower pressures in such limbs Figure .2 Comparison of intra-arterial blood pressure in the arms and legs in humans shows that the femoral systolic blood pressure is approximately the same as that in the brachial artery. Figure Schematic representation of a a straight tourniquet and b a curved tourniquet. Straight tourniquets fit optimally on cylindrical limbs while curved tourniquets are designed to fit conical limbs. Reprinted with permission of Lippincott Williams Wilkins from Pedowitz RA Gershuni DH Botte MJ et al. 1993 . The use of lower tourniquet inflation pressures in extremity surgery facilitated by curved and wide tourniquets and an integrated cuff inflation system. Clinical Orthopaedics and Related Research 287 237-243. @ @ @ Effect of the Tourniquet on the Limb The principles for cuffs used as sphygmomanometers are also applicable to cuffs used as tourniquets although allowances must be made for the situation in the operating theatre. Fluctuations of blood pressure may occur due to operative trauma for the upper limb an additional pressure of 50-75 mm Hg above systolic pressure limb occlusion pressure should be