Cyclic injection method for continuous measurements of pulmonary parameters

Claim 1

In a method of sampling and analyzing alveolar air is a human subject without requiring an airtight seal between the subject and monitoring equipment to determine alveolar ventilation by means of injecting a known amount of an insoluble inert tracer gas into the airway of a subject by non-airtight means, during inspiration and directly sampling expired alveolar air by non-airtight means and monitoring the inert tracer gas concentration in expired air under steady state conditions to determine alveolar ventilation, the improvement which consists of determining additional pulmonary parameters, comprising the steps of: (a) directly introducing the known amount of insoluble inert tracer gas during each inspiratory cycle for a given period of time designated as a washin cycle and then halting the introduction of such gas for a given period of time designated as a washout cycle, (c) simultaneous with the introduction of the insoluble tracer gas, introducing one or more additional tracer gases which are at least partially soluble in blood for the same washing cycle and then halting the introduction of said soluble tracer gas or gases for the same washout cycle, (c) continuously repeating said washin and washout cycles and sampling and monitoring the insoluble and soluble gas fractions in sampled expired alveolar air, and (d) utilizing the monitored data to determine the desired pulmonary parameter.

Claim 11

A method for determining the ventilation-perfusion distribution in a human subject which comprises: a. directly introducing a gaseous mixture of tracer gases into the airway of said subject during each inspiratory cycle for a given period of time designated as a washin cycle and then halting the introduction of such mixture for a given period of time designated as a washout cycle, said gas consisting of one inert tracer gas which is relatively insoluble in blood and one or more inert tracer gases which are at least partially soluble in blood wherein the ratio of each soluble gas to the insoluble gas is known, b. continuously repeating said washin and washout cycles, c. sampling expired alveolar air from each cycle and monitoring the one or more ratios of said one or more soluble tracer gases to insoluble tracer gas in the sampled expired alveolar air, and d. utilizing the monitored data obtained from sampled alveolar air along with the known ratios of tracer gases cyclically introduced to determine ventilation-perfusion distribution.

Claim 12

A method for determining the ventilation-perfusion distribution in a human subject which comprises: a. directly introducing a gaseous mixture of tracer gases into the airway of said subject during each inspiratory cycle for a given period of time designated as a washin cycle and then halting the introduction of such mixture for a given period of time designated as a washout cycle, said gas consisting of one inert tracer gas which is relatively insoluble in blood and one or more inert tracer gases which are at least partially soluble in blood wherein the ratio of each soluble gas to the insoluble gas is known, b. continuously repeating said washin and washout cycles, c. sampling expired alveolar air from each cycle and monitoring the one or more ratios of said one or more soluble tracer gases to insoluble tracer gas in the sampled expired alveolar air, and d. utilizing the monitored data obtained from sampled alveolar air along with the known ratios of tracer gases cyclically introduced to determine ventilation-perfusion distribution.