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Respiratory calorimeter with bidirectional flow monitors for calculating of oxygen consumption and carbon dioxide production

  • US 5,178,155 A
  • Filed: 12/31/1991
  • Issued: 01/12/1993
  • Est. Priority Date: 06/29/1988
  • Status: Expired due to Term
First Claim
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1. An indirect calorimeter operative to measure the respiratory oxygen consumption and carbon dioxide production per unit time of a subject breathing respiratory gases comprising:

  • a respiratory connector operative to be supported in contact with the subject so as to pass inhaled and exhaled gases as the subject breathes;

    means for connecting to a source of said respiratory gases;

    a first pass-through bidirectional flow meter adapted to generate electrical signals as a function of the volume of gases which pass through it in either direction;

    a second flow meter adapted to generate electrical signals as a function of the gases that pass through it;

    a pass-through carbon dioxide scrubber operative to absorb carbon dioxide from gases which pass through it;

    conduits interconnecting said respiratory connector said means for connecting to a source of respiratory gases, said scrubber and said first and second flow meters so that upon inhalation by the patient gases are passed from the source of respiratory gases, through the first flow meter, to the subject through the respiratory connector and upon exhalation by the subject the exhaled gases are passed first through the second flow meter, then through the scrubber, then through the first flow meter in a direction opposite to the inhaled gases; and

    means for receiving the signals from the first and second flow meters and for generating a first signal proportional to the integrated difference between the inhaled and exhaled gas volumes after passage through the scrubber over a period of time to calculate the oxygen consumption and a second signal proportional to the integrated differences between the exhaled gas volumes before and after being scrubbed to calculate the carbon dioxide production.

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