Impedance plethysmograph

• US 3,340,867 A
• Filed: 08/19/1964
• Issued: 09/12/1967
• Est. Priority Date: 08/19/1964
• Status: Expired due to Term

• Current Assignee: David A. Witsoe, Edwin Kinnen, Robert P. Patterson, William G. Kubicek
• Original Assignee: David A. Witsoe, Edwin Kinnen, Robert P. Patterson, William G. Kubicek
• Inventors: Kubicek, William G., EDWIN KINNEN, Patterson, Robert P., Witsoe, David A.
• Application Number:
  US04/390,555
• Time in Patent Office: 1,119 Days
• US Class Current: 600/526
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295

Claims

1. A PLETHYSMOGRAPH FOR MEASURING CARDIAC OUTPUT COMPRISING IN COMBINATION EXCITATION ELECTRODE MEANS ADAPTED TO BE CONNECTED TO A MAMMALIAN SUBJECT AT THE SUPERIOR AND INFERIOR ENDS OF THE THORAX, A CURRENT GENERATOR MEANS COMPRISING AN ELECTRONIC OSCILLATOR CONDUCTIVELY CONNECTED TO THE ELECTRODE MEANS FOR SUPPLYING A FLUCTUATING EXCITATION CURRENT THERETO, SENSOR MEANS ADAPTED TO BE CONDUCTIVELY CONNECTED TO SAID THORAX FOR CARRYING A SENSED ELECTRICAL SIGNAL WHICH VARIES AS THE IMPEDANCE CHANGES IN THE THORAX BETWEEN SAID ELECTRODE MEANS, A CONTROL MEANS CONDUCTIVELY CONNECTED TO THE OSCILLATOR FOR BALANCING THE CURRENT FROM THE OSCILLATOR WITH THE SENSED SIGNAL, A FIRST AMPLIFIED CONDUCTIVELY CONNECTED TO THE CONTROL MEANS, A SECOND AMPLIFIER CONNECTED TO SAID SENSOR MEANS WHEREBY SIGNALS OF APPROXIMATELY EQUAL STRENGTH ARE FED TO SAID FIRST AND SECOND AMPLIFIERS FROM SAID CONTROL AND SAID SENSOR MEANS RESPECTIVELY AND A VOLTAGE SUBSTRACTING MEANS CONDUCTIVELY CONNECTED TO EACH OF THE AMPLIFIERS FOR COMPARING THE OUTPUT OF EACH SAID AMPLIFIER.