No abstract

The literature indicates that tourniquet-induced neurological injuries are relatively common and frequently occur at a subclinical level. In order to evaluate the pressure transmitted to the major peripheral nerves of the arm by an externally applied pneumatic tourniquet, a fully implantable biomedical pressure transducer was placed adjacent the radial, median and ulnar nerves in six cadaver upper extremities of average dimensions. This sensor allowed accurate, reproducible measurements of perineural pressures without requiring significant disruption of the normal anatomical structures of the test limb for its installation. At levels of tourniquet cuff inflation which are commonly used in clinical practice, there was little or no decrease in the pressure detected in the perineural regions over that applied to the surface of the limb. In addition, there was a steep gradient of perineural pressure between locations beneath the edge of the cuff and those under its midpoint. This was most marked at the highest levels of tourniquet inflation. At presently accepted levels of inflation, pneumatic tourniquet cuffs transmit high pressures to the peripheral nerves without any significant attenuation by the intervening soft tissues. The distribution of these forces is one which may subject the underlying nerves to deleterious shear forces, especially at higher levels of inflation.

No abstract

The tourniquet pressure at which blood flow occlusion occurs was measured in the laboratory on 34 subjects and conelated with three basic parameters: tourniquet cuff width, limb circumference, and blood pressure. Blood flow occlusion data was also obtained and verified by clinically measuring occlusion pressure on 23 patients in the operating mom. Using this data empirical relationships were obtained to allow prediction of blood flow occlusion under a tourniquet cuff for normal use in orthopaedic ~Urgery.

No abstract