Method and apparatus for assessing blood-concentration of a volatile constituent
First Claim
1. A method of assessing the blood concentration level, in a human or animal subject, of a volatile blood constituent, the method comprising the steps of:
- positioning sensor means within the expiratory gas-flow of the subject, the sensor means being configured to detect the presence of the constituent and provide a first output signal representative of the concentration of the constituent, and to detect the presence of carbon dioxide and provide a second output signal representative of the concentration of carbon dioxide; and
sampling a flow of expiratory gases from the subject using the sensor means to provide the first output signal and the second output signal for the expiratory gases substantially simultaneously; and
inputting the first and second output signals obtained by the sampling step into an algorithm configured to compare the variation of the first output signal over time with the variation of the second output signal over time and, depending on the result of the comparison, to make the second signal representative of the degree of dilution of the expiratory airflow whereby the blood concentration level of the blood constituent is assessed.
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Abstract
A method and apparatus for of assessing the blood concentration level in a human or animal subject, of a volatile blood constituent (preferably alcohol) is disclosed. The method comprises steps of positioning a sensor (21, 22) within the expiratory gas flow of the subject, wherein the sensor (21, 22) is configured to detect the presence of the constituent and provide a first output signal representative of the concentration of said constituent in air, and also to detect a presence of carbon dioxide and to provide a second output signal representative of the concentration of carbon dioxide in air. The flow of expiratory gases from the subject is sampled to provide a first signal and second signal in respect of the expiratory gases substantially simultaneously. The method also comprises the step of inputting said first and second signals obtained by the sampling step into an algorithm configured to compare the variation of the first signal over time with the variation of the second signal over time and, depending on the result of the comparison, to make said second signal representative of the degree of dilution of said expiratory airflow. The invention further includes an apparatus for carrying out the method.
43 Citations
30 Claims
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1. A method of assessing the blood concentration level, in a human or animal subject, of a volatile blood constituent, the method comprising the steps of:
- positioning sensor means within the expiratory gas-flow of the subject, the sensor means being configured to detect the presence of the constituent and provide a first output signal representative of the concentration of the constituent, and to detect the presence of carbon dioxide and provide a second output signal representative of the concentration of carbon dioxide; and
sampling a flow of expiratory gases from the subject using the sensor means to provide the first output signal and the second output signal for the expiratory gases substantially simultaneously; and
inputting the first and second output signals obtained by the sampling step into an algorithm configured to compare the variation of the first output signal over time with the variation of the second output signal over time and, depending on the result of the comparison, to make the second signal representative of the degree of dilution of the expiratory airflow whereby the blood concentration level of the blood constituent is assessed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
- positioning sensor means within the expiratory gas-flow of the subject, the sensor means being configured to detect the presence of the constituent and provide a first output signal representative of the concentration of the constituent, and to detect the presence of carbon dioxide and provide a second output signal representative of the concentration of carbon dioxide; and
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27. An apparatus to access the blood concentration level of a volatile blood constituent of a human subject comprising sensor means positionable within the expiratory gas-flow of the subject, the sensor means being configured to detect the presence of the blood constituent and provide a first output signal representative of the concentration of the blood constituent, and to detect the presence of carbon dioxide and provide a second output signal representative of the concentration of carbon dioxide, a processor for processing the first and second output signals and implementing a sampling step using an algorithm to compare the variation of the first output signal over time with the variation of the second output signal over time, a memory carrying the algorithm:
- and the processor configured to process the output signals in accordance with the algorithm stored in the memory and accessing the concentration level of the blood constituent.
- View Dependent Claims (28, 29, 30)
Specification