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Blood loss meter

  • US 3,182,252 A
  • Filed: 12/16/1960
  • Issued: 05/04/1965
  • Est. Priority Date: 12/16/1960
  • Status: Expired due to Term
First Claim
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1. A BLOOD LOSS METER COMPRISING A MEASURING VESSEL ADAPTED TO RECEIVE A WASHING LIQUID OF KNOWN ELECTRIC CONDUCTIVITY, AN AGITATOR IN SAID MEASURING VESSEL ADAPTED FOR MIXING THE BLOOD ADSORBED BY DRESSINGS WITH SAID WASHING LIQUID, AN A.C. BRIDGE CIRCUIT INCLUDING FOUR JUNCTIONS AND FOUR ARMS CONNECTED BETWEEN THE SAID JUNCTIONS, AN ALTERNATING CURRENT SOURCE CONNECTED BETWEEN TWO DIAMETRICALLY OPPOSED JUNCTIONS, A PAIR OF ELECTRODES IN SAID MEASURING VESSEL AND CONNECTED IN A FIRST ARM OF SAID BRIDGE CIRCUIT, A FIRST RESISTOR, A SECOND RESISTOR IN SERIES WITH SAID FIRST RESISTOR AND CONNECTED TOIGETHER WITH THE SAME IN A SECOND ARM OF SAID BRIDGE CIRCUIT DIAMETRICALLY OPPOSED TO SAID FIRST ARM, A VARIABLE THIRD RESISTOR IN PARALLEL WITH SAID FIRST RESISTOR, A FOURTH RESISTOR CONNECTED IN A THIRD ARM OF SAID BRIDGE CIRCUIT, A RESISTIVE IMPEDANCE CONNECTED IN THE FOURTH ARM OF SAID BRIDGE CIRCUIT, AN AMPLIFIER HAVING AN INPUT CONNECTED WITH THE REMAINING DIAMETRICALLY OPPOSED JUNCTIONS OF SAID BRIDGE CIRCUIT, A SERVO-MOTOR COUPLED TO SAID AMPLIFIER AND CONTROLLING SAID THIRD RESISTOR TO KEEP THE BRIDGE CIRCUIT IN EQUILIBRIUM, AN INDICATOR MECHANICALLY COUPLED WITH SAID THIRD RESISTOR, A SCALE CALIBRATED IN VOLUME PARTS OF BLOOD AND POSITIONED OPPOSITE TO SAID INDICATOR, MEANS FOR ADJUSTING THE RATIO BETWEEN THE RESISTANCE VALUES OF SAID FIRST AND SAID SECOND RESISTOR, SO THAT THIS RATIO MAY BE ADJUSTED, FOR A GIVEN PATIENT, TO (G2-G1):

  • G1, WHEREIN G1 IS THE ELECTRIC CONDUCTIVITY OF THE

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