The impact of total body water on breath alcohol calculations
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Wien Klin Wochenschr https://doi.org/10.1007/s00508-020-01663-4
The impact of total body water on breath alcohol calculations Gregor S. Reiter · Markus Boeckle · Christian Reiter · Monika H. Seltenhammer
Received: 1 March 2020 / Accepted: 12 April 2020 © The Author(s) 2020
Summary Due to a legislative amendment in Austria to determine breath alcohol (BrAC) instead of blood alcohol (BAC) in connection with traffic offences, many results of blood alcohol calculations were simply converted using distinct conversion factors. In Austria, the transformation of BAC to BrAC was carried out by using a factor of 1:2000, which, however, is commonly known to be too low. Noticing the great demand for a calculation method that is not exclusively based on blood alcohol, a formula for calculating breath alcohol based on blood alcohol was published in 1989, but in which the body surface area (BSA) was considered the most important influencing variable. In order to refine this new method, a liquor intake experiment was conducted combined with measurements of total body water (TBW) as an additional variable, using hand to foot bioelectrical impedance assessment (BIA). The test group comprised 37 men and 40 women to evaluate the accuracy of TBW and BSA as an individual parameter for alcohol concentration. The correlation coefficient of
BrAC with TBW was constantly higher than with BSA (maximum = 0.921 at 1 h and 45 min after cessation of alcohol intake). These results are valid for both men and women as well as in a gender independent calculation. Hence, for an accurate back calculation of BrAC adjusted values of eliminations rates had to be found. This study describes mean elimination rates of BrAC for both men (0.065 ± 0.011 mg/L h–1) and women (0.074 ± 0.017 mg/L h–1). As previously shown women displayed a significantly higher elimination rate than men (p = 0.006). Keywords Bioelectrical impedance assessment (BIA) · Blood alcohol concentration (BAC) · Forensic back calculation · Body surface area (BSA) · Genderspecific differences
Introduction
M. H. Seltenhammer Division of Life Stock Sciences, University of Natural Resources and Life Sciences, Vienna, Austria
Evidence of alcohol in the breath was already mentioned in the nineteenth century [1, 23]. In 1927 a potential relationship between blood alcohol concentration (BAC) and breath alcohol concentration (BrAC) was described by Bogen [4]. Soon afterwards, Liljestrand and Linde presented a conversion factor of 1:2000 from BAC to BrAC [23, 29]. This specific conversion factor, commonly shortened to Q, has already been discussed and revised in many different publications [10, 16, 21, 26, 33]. Basically, the threshold of blood alcohol level punishable under Austria’s legislation is 0.5 parts per thousand, which corresponds to 0.25 mg/L BrAC. Due to practical reasons, the usage of BrAC has a more important role than BAC in Austria because of the 13th amendment of the Road Traffic Act (StVO) in 1986 in which blood sampling was almost entirely replaced by breath testing [38]. Whil
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