## Introduction

_{p}stands for BrAC at time zero measured in g/l, gAlk for the amount of alcohol intake measured in grams, ES for the contents of the stomach, which has a value between 0 for empty stomach and 1 for full stomach and BSA [14].

^{2}[15]. Based on these considerations an improvement of the calculation of BrAC has to be found which does not only include the height and weight of the tested person, but also an individual volume of distribution for alcohol.

## Material and methods

### Subjects and conditions

### Breath alcohol concentration analysis

### Bioelectrical impedance assessment

### Calculation of derived variables

_{0}) had to be calculated. In doing so, BrAC measurements at 90 min and 150 min were used for each participant and integrated at 0, with a largely zero-order kinetics of alcohol elimination being assumed. A safety time distance after the peak BrAC and the moderate amount of intake before changing to a different kind of kinetics at a low alcohol concentration was taken into account [18, 21, 31, 32].

_{0}. Individualized elimination rates were calculated by subtracting the value of the BrAC at 150 min from the BrAC at 90 min.

### Statistical analysis

_{0}, in particular to clarify whether BSA or TBW is the better predictor for BrAC

_{0}. The BrAC

_{0}was determined by interpolating the slope between 90 min and 150 min. Additional candidate variables used were sex, age, body weight, and body size. Corrected Akaike information criteria (AIC

_{c}) were used to select the most parsimonious model [5]. Significant differences between models were calculated using ANOVA. All analyses were calculated with IBM SPSS Statistics for Mac v. 21 (IBM Österreich, Vienna, Austria). All residuals of the models conformed to normality. The alpha level was set at 0.05 (two-tailed). Descriptive statistical values are presented in mean ± standard deviation.

## Results

Mean | Standard deviation | Minimum | Maximum | ||
---|---|---|---|---|---|

All (N = 77) | Age (years) | 31.09 | 11.88 | 18 | 60 |

Body size (cm) | 174.14 | 8.84 | 155 | 194 | |

Body weight (kg) | 71.87 | 17.34 | 47.6 | 140 | |

Male (N = 37) | Age (years) | 30.62 | 11.88 | 21 | 60 |

Body size (cm) | 181.19 | 5.28 | 166 | 194 | |

Body weight (kg) | 80.35 | 15.67 | 57 | 140 | |

Female (N = 40) | Age (years) | 31.52 | 12.02 | 18 | 55 |

Body size (cm) | 167.63 | 5.99 | 155 | 178 | |

Body weight (kg) | 64.03 | 15.08 | 47.6 | 127 |

^{2}, and a BrAC

_{0}of 0.358 ± 0.093 mg/L. The mean BrAC

_{0}for men was 0.291 ± 0.044 mg/L, whereas the mean BrAC

_{0}for women was 0.421 ± 0.084 mg/L. The mean volume of TBW for men was 43.549 ± 4.935 L and 31.28 ± 3.743 L for women. The elimination rate of breath alcohol per hour was 0.0699 ± 0.015 mg/L h

^{−1}. There was a sex-specific difference in the elimination rate (T

_{75}= 2.847; p = 0.006; N = 77) whereby the male elimination rate was 0.065 ± 0.011 mg/L h

^{−1}while the female elimination rate was 0.074 ± 0.017 mg/L h

^{−1}(Fig. 1).

_{0}correlated significantly in the complete sample with TBW (r

_{s}= −0.889; p ≤ 0.001; N = 77) and BSA (r

_{s}= −0.865; p ≤ 0.001; N = 77). When correlations were calculated in the female sample BrAC

_{0}showed a negative correlation with TBW (r = −0.835; p ≤ 0.001; N = 40) and BSA (r = −0.801; p ≤ 0.001; N = 40). We found similar correlations in males (BrAC_TBW: r = −0.759; p ≤ 0.001; N = 37; BrAC_BSA: r = −0.682; p ≤ 0.001; N = 37). The correlations were not significantly different (p > 0.05) between sexes.

BrAC _{0} | 90min | 120min | 150min | |||
---|---|---|---|---|---|---|

All (N = 77) | TBW | r _{s} | −0.889 | −0.919 | −0.921 | −0.901 |

BSA | r _{s} | −0.865 | −0.897 | −0.899 | −0.879 | |

Female (N = 40) | TBW | r | −0.827 | −0.896 | −0.909 | −0.884 |

BSA | r | −0.804 | −0.852 | −0.868 | −0.829 | |

Male (N = 37) | TBW | r | −0.682 | −0.763 | −0.733 | −0.693 |

BSA | r | −0.652 | −0.745 | −0.714 | −0.684 |

_{0}based on TBW was the model including TBW alone with an AIC

_{c}of −470.75. The BrAC

_{0}is best predicted by TBW (F

_{1.75}= 234.257; p ≤ 0.001), with a large influence of TBW on BrAC

_{0}(β = −0.011; t = −15.305; p ≤ 0.001). The final model for predicting BrAC

_{0}based on BSA results in a significant influence of BSA (F

_{1.74}= 84.103; p ≤ 0.001) and sex (F

_{1.74}= 11.704; p ≤ 0.001) with an AIC

_{c}of −468.55. The BSA has a large influence (β = −0.285; t = −9.171; p ≤ 0.001) and females showed a higher elimination rate than males (β = −0.047; t = −3.421; p ≤ 0.001). When calculating a model with the influence of BSA (AIC

_{c}= −459.41) on BrAC

_{0,}we found just such an influence (F

_{1.75}= 191.913; p ≤ 0.001) with a large effect (β = −0.353; t = −13.853; p ≤ 0.001). When comparing the three models TBW best explains the variance of BrAC

_{0}data (p ≤ 0.05).

## Discussion

^{–1}; depending on the type of offense. Still, it is well known that elimination rates can be higher, especially for women [11, 21]. Different elimination rates for BAC were demonstrated and verified in several experiments [11, 24, 21]. When applying blood alcohol testing these results are useful enough; however, as soon as breath alcohol testing is carried out, new values have to be utilized in order to avoid bias from the conversion process. Unfortunately, the units of BrAC differ in many countries. Pavlic et al. as well as Dettling et al. published breath alcohol elimination rates using the unit mg/L h

^{−1}, which was also performed in this study [11, 34]. The mean elimination rate for both sexes in our study was 0.0699 ± 0.002 mg/L h

^{−1}. For men the mean elimination rate was 0.065 ± 0.002 mg/L h

^{−1}, for women 0.074 ± 0.003 mg/L h

^{−1}. These results are quite comparable with those already described and can definitely be used for more accurate elimination rates of breath alcohol.

## Conclusion

^{−1}with the mean elimination rates of 0.065 ± 0.002 mg/L h

^{−1}in men and 0.074 ±0.003 mg/L h

^{−1}in women. The results from this study are comparable with those in the current literature. The expectation that women have a significant higher elimination rate than men could be confirmed (p = 0.006).