A occlusion detector for a dual-port surgical tourniquet system comprises: atourniquet cuff for encircling a patient's limb and including an inflatableportion that communicates pneumatically with a first cuff port and thatcommunicates pneumatically with a second cuff port independently of the firstcuff port； a tourniquet instrument that is releasably connectable to the firstand second cuff ports to establish first and second pneumatic passagewaysbetween the tourniquet cuff and the tourniquet instrument, wherein thetourniquet instrument includes pressure sensing means communicating with thefirst pneumatic passageway for producing an indication of the pressure in thecuff over a time period suitably long for the performance of a surgicalprocedure, pressure regulation means communicating with the second pneumaticpassageway for regulating the pressure in the cuff near a reference pressurelevel, and an occlusion detector for introducing a pneumatic pressure pulseinto the first pneumatic passageway during an occlusion detection time period,for monitoring the pressure in the second pneumatic passageway during theocclusion detection time period, and for producing an occlusion alarm if afluctuation of pressure in the second pneumatic passageway is not detectedwithin the occlusion detection time period.
