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Method of determining the conductivity of blood

  • US 5,827,192 A
  • Filed: 08/21/1996
  • Issued: 10/27/1998
  • Est. Priority Date: 08/21/1996
  • Status: Expired due to Fees
First Claim
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1. In a process of determining cardiac volume by the conductance catheter method, the improvement comprising a method of determining the absolute electrical conductivity of blood as a part of said process comprising the steps of positioning in the ventricle of a mammalian heart a catheter comprising an elongate body having an outer surface and a plurality of spaced electrodes disposed on its outer surface, determining which pair of adjacent electrodes of the plurality of electrodes is optimally positioned to determine resistivity of the blood in the ventricle and selecting the pair of electrodes, applying a current of known magnitude to the selected pair of electrodes, measuring the voltage between the selected pair of electrodes and determining the absolute conductivity of the blood from the expression:

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    space="preserve" listing-type="equation">S=IKc/VwhereI=the applied current,V=the measured voltage, andKc=a calibration ratio dependent upon electrode geometry and spacing.

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