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Non-airtight pulmonary measuring device

  • US 4,221,224 A
  • Filed: 06/29/1978
  • Issued: 09/09/1980
  • Est. Priority Date: 06/29/1978
  • Status: Expired due to Term
First Claim
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1. A method of sampling and analyzing alveolar air in a human subject without requiring an air-tight seal between the subject and the monitoring equipment to determine alveolar ventilation, carbon dioxide production and oxygen uptake comprising the steps of;

  • (a) determining the onset of inspiration,(b) directly introducing a known amount of an inert tracer gas into the airway of the patient by non-airtight catheter means during inspiration such that the inert tracer gas is distributed in the inspired air and is carried to the alveoli, leaving essentially no tracer gas in the anatomical dead space,(c) determining the onset of expiration of alveolar air and directly sampling a portion of alveolar air by a non-airtight catheter means and monitoring the inert gas concentration of a portion of the alveolar air stream by non-airtight means,(d) repeating cycles (b) and (c) until a steady state in the concentration of inert tracer gas is reached,(e) continuing cycles (b) and (c) and monitoring the oxygen and carbon dioxide concentrations in the portion of the alveolar air stream at steady state inert tracer gas concentrations, and,(f) determining the alveolar ventilation, carbon dioxide production and oxygen uptake from the monitored inert tracer gas, carbon dioxide and oxygen values.

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