Method for measuring the concentration of gas molecules in the respiratory and circulatory system in exhaled breath

Abstract

The invention provides a measuring method for the concentration of gas molecules from a respiratory and circulatory system in expired gas to realize acquisition and analysis of nitric oxide gas in expired gas in a tidal breathing state. According to the method, when tidal breathing flow is greater than 150 ml / s and airway retention time is less than 1 s, changes of the concentration of CO2 in the expired gas are monitored by using a CO2 monitoring module; the concentration Ce of the expired gas X at different time points is measured; according to the breathing state displayed by a CO2 curve, the concentration Ce at at least two time points, i.e., Ce(t1) and Ce(t2), when the expired gas X is in an alveolar area is selected; since the contribution of Caw in an airway area can be neglected during high flow, Ce(t) is approximately equal to Calv(t); thus, the concentration Ca of X in the alveolar area and the concentration Cw of X entering alveoli after circulation can be calculated according to the equation that Calv(t) = Ca + kCw.

Description

technical field [0001] The invention relates to a method for measuring the concentration of gas molecules in exhaled air. Background technique [0002] It is known that the measurement of various gas molecular components and their concentrations in the exhaled air of the human body can assist doctors in diagnosing patients' diseases, monitoring disease states and observing treatment effects, etc. The source of a certain gas molecule X in the breath is mainly the sum of the gas X1 produced and exhaled by the respiratory system and the gas X2 produced by other systems and passed to the respiratory system through the circulatory system and exhaled. The respiratory system can be subdivided into airway and alveolar parts, so X can be subdivided into airway produced and exhaled gas X11, alveolar produced and exhaled gas X12, and other systems produce gas that is delivered to the alveoli through the circulatory system sum of x2. [0003] CASE1: For some gas molecules X, such as C...

AI Technical Summary

Problems solved by technology

For example, for exhaled CO molecules, CareFusion’s Micro CO analyzer or Natus Medical, Inc.’s CO-STAT end-tidal analyzer are only used to analyze and measure the end-tidal CO concentration, and cannot distinguish whether the CO concentration is From the concentration of gas X12 produced by the alveoli or the concentration of gas X2 circulating to the alveolar area from other systems

For exhaled NO molecules, the prior art J.Breath Res. 6 (2012) 047103 proposes to distinguish airway gas NO and alveolar NO, which distinguishes airway NO (X11) and alveolar NO ( sum of X12 and X2), but cannot distinguish X12 produced by the alveoli from X2 produced by other systems and diffused to the alveoli

[0009] Since CO or NO produced by the alveoli and other systems cannot be distinguished, the measurement of end-tidal CO or NO in the alveolar area has not yet formed a standardized or quantitative diagnostic technique

Images