Abstract: Apparatus for assisting in the administration of anesthesia in a portion of a patient's limb distal to a cuff comprises in combination: applied pressure transducing means for generating an applied pressure signal representative of a pressure applied to a limb by a cuff which encircles the limb and applies pressure to the limb; anesthetic pressure sensing means for sensing the pressure of anesthetic liquid in a vein distal to the cuff and for generating an anesthetic liquid pressure signal indicative of the pressure; and alarm means for producing an alarm signal when the difference between the pressures corresponding to the applied pressure signal and the anesthetic liquid pressure signal is less than a preassigned safety limit.

Abstract: Tourniquet apparatus for use in intravenous regional anesthesia and limb surgery includes a pressurizing cuff for substantially encircling a limb and applying a varying pressure to an underlying vein in response to variations in a pressure control signal, applied venous pressure sensing means for producing an applied venous pressure signal representative of a pressure applied by the cuff to the underlying vein, venous fluid pressure estimation means for producing a venous fluid pressure signal representative of the pressure of fluid in the vein distal to the cuff, and pressure control means responsive to the venous fluid pressure signal and applied venous pressure signal for generating a pressure control signal to maintain a predetermined relationship between the applied venous pressure signal and the venous fluid pressure signal. The apparatus automatically controls the introduction, retention and release of anesthetic fluid in the limb.