Non-airtight pulmonary measuring device
First Claim
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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Accused Products
Abstract
A non-airtight method for determining alveolar ventilation, oxygen uptake and carbon dioxide production which comprises introducing a known amount of an inert gas into the airway of a patient during inspiration and monitoring the expired gas until a steady state is reached wherein the volume of inert gas inhaled is equal to the amount exhaled and subsequently monitoring the expired air containing a known volume of inert gas for inert gas, carbon dioxide and oxygen concentrations.
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Citations
17 Claims
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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;
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(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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system suitable for determining alveolar ventilation, carbon dioxide production and oxygen consumption comprising,
(a) means which do not require an airtight seal to a patient adapted to supply a known amount of an inert tracer gas into the airway of a patient duriing inspiration, (b) sampling means which do not require an airtight seal to a patient adapted to withdraw a portion of expired alveolar air stream from the airway of a patient, (c) actuator means adapted to sense the onset of inspiration in a patient and immediately terminate operation of said sampling means in response thereto and to initiate operation of said inert tracer gas supplying means at a predetermined time relative to the onset of inspiration, (d) actuator means adapted to sense the onset of expiration and to initiate operation of said sampling means at a time subsequent to the onset of expiration according to a predetermined sensed parameter, (e) means for analyzing gas collected from said sampling means and from ambient air, (f) means for supplying gas from said sampling means and from ambient air to said analyzing means, (g) means connected to said analyzing means adapted to receive signals from said analyzing means and to translate said signals into visual results indicating alveolar ventilation, carbon dioxide production and oxygen uptake.
Specification