[Blood pressure-dependent, process-controlled hemostasis to minimize tourniquet syndrome]

The usual limitation of the pneumatic blood arrest period to 1.5 hours is a protective measure in order to prevent permanent injuries due to tissular hypoxia and local pressure. The generally applied cuff pressure of 300 mm Hg for the upper and 500 mm Hg for the lower extremity is an arbitrary value which has been obtained by empiric research and is completely lacking in scientific foundation. The risk of damaging tissues lying under the cuff which are sensitive to pressure would be considerably reduced by decreasing this pressure to a value just beyond the systolic blood pressure. The differences between systolic pressure and cuff pressure leading to a safe blood arrest in the extremity operated upon have been determined in narcotized patients. It was shown that the cuff pressure only has to be a little higher than the systolic blood pressure in order to produce a constant blood arrest. This difference, however, is also dependent on the circumference of the extremity as well as on the age and sex of the patient and the tissue turgor. It was therefore necessary to construct a unit providing a permanent pressure control in the pneumatic blood arrest cuff depending on the variations of blood pressure during surgical intervention. This was obtained by the use of rapidly working minicomputers and new monitoring devices.