Improved breath alcohol analysis with use of carbon dioxide as the tracer gas

Mälardalen University Press Dissertations

No. 83

IMPROVED BREATH ALCOHOL ANALYSIS WITH USE OF

CARBON DIOXIDE AS THE TRACER GAS

Annika Kaisdotter Andersson

2010

         

Copyright © Annika Kaisdotter Andersson, 2010

ISSN 1651-4238

ISBN 978-91-86135-77-5

Mälardalen University Press Dissertations

No. 83

IMPROVED BREATH ALCOHOL ANALYSIS WITH USE OF CARBON DIOXIDE AS

THE TRACER GAS

Annika Kaisdotter Andersson

Akademisk avhandling

som för avläggande av teknologie doktorsexamen i elektronik vid Akademin för

innovation, design och teknik kommer att offentligen försvaras fredagen

den 10 september, 2010, 10.15 i Milos, Mälardalens högskola, Västerås.

Fakultetsopponent: Dr. Johannes Lagois, Dräger Safety AG & CO

Abstract

State-of-the-art breath analysers require a prolonged expiration into a mouthpiece to obtain the accuracy required for evidential testing and screening of the alcohol concentration. This requirement is unsuitable for breath analysers used as alcolock owing to their frequent use and the fact that the majority of users are sober drivers; as well as for breath testing in uncooperative persons.

This thesis presents a method by which breath alcohol analysis can be improved, using carbon dioxide (CO2) as the tracer gas, offering quality control of the breath sample, enabling the mouthpiece to be

eliminated, and bringing about a significant reduction in the time and effort required for a breath alcohol screening test. With simultaneous measurement of the ethanol and the CO2 concentrations in the expired

breath, the end-expiratory breath alcohol concentration (BrAC) can be estimated from an early measurement, without risk of underestimation.

Comparison of CO2 and water as possible tracer gases has shown that the larger intra- and

inter-individual variations in the (end-expiratory) concentration is a drawback for CO2 whereas the

advantages are a low risk of underestimation of the BrAC, and the limited influence from ambient conditions on the measured CO2 concentration. The latter is considered to be of importance because the

applications likely imply that the breath tests will be conducted in an uncontrolled environment, e.g., in a vehicle or ambulance. In emergency care, the measurement of the expired CO2 concentration also

provides the physicians with information about the patient's respiratory function.

My hope and belief, is that with a more simple, reliable and, user-friendly test procedure, enabled with the simultaneous measurement of the CO2 in the breath sample, the screening for breath alcohol will

increase. An increased number of breath alcohol analysers installed as alcolocks and more breath alcohol tests conducted in emergency care, is likely to save lives and diminish the number and severity of injuries.

ISSN 1651-4238

Abstract

State-of-the-art breath analysers require a prolonged expiration into a mouthpiece to obtain the accuracy required for evidential testing and screening of the alcohol concentration. This requirement is unsuitable for breath analysers used as alcolock owing to their frequent use and the fact that the majority of users are sober drivers; as well as for breath testing in uncooperative persons.

This thesis presents a method by which breath alcohol analysis can be improved, using carbon dioxide (CO2) as the tracer gas, offering quality control of the breath sample, enabling the mouthpiece to be

eliminated, and bringing about a significant reduction in the time and effort required for a breath alcohol screening test. With simultaneous measurement of the ethanol and the CO2 concentrations in the expired

breath, the end-expiratory breath alcohol concentration (BrAC) can be estimated from an early measurement, without risk of underestimation.

Comparison of CO2 and water as possible tracer gases has shown that the larger intra- and

inter-individual variations in the (end-expiratory) concentration is a drawback for CO2 whereas the

advantages are a low risk of underestimation of the BrAC, and the limited influence from ambient conditions on the measured CO2 concentration. The latter is considered to be of importance because the

applications likely imply that the breath tests will be conducted in an uncontrolled environment, e.g., in a vehicle or ambulance. In emergency care, the measurement of the expired CO2 concentration also

provides the physicians with information about the patient's respiratory function.

My hope and belief, is that with a more simple, reliable and, user-friendly test procedure, enabled with the simultaneous measurement of the CO2 in the breath sample, the screening for breath alcohol will

increase. An increased number of breath alcohol analysers installed as alcolocks and more breath alcohol tests conducted in emergency care, is likely to save lives and diminish the number and severity of injuries.

ISSN 1651-4238

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