Breath Alcohol Concentration Measurements Research Articles

Changes in alcohol consumption during the COVID-19 pandemic: a longitudinal cohort study using smart-breathalyzer data

Previous studies relying on alcohol sales, alcohol-related injuries, and surveys have suggested that alcohol consumption increased during the COVID-19 pandemic. We sought to leverage over 1 million Breath Alcohol Concentration (BrAC) measurements from Bluetooth-enabled breathalyzers to conduct an objective and longitudinal assessment of alcohol use during the pandemic. Serial BrAC measurements revealed a decrease in drinking between January 1, 2020 and March 30, 2020, an increase between March 30, 2020 and May 25, 2020, a statistically insignificant decrease between May 25, 2020 and January 1, 2021, and an increase again between January 1, 2021 and June 4, 2021. No statistically significant relationships between shelter-in-place orders and alcohol consumption were detected. These findings demonstrate the complex relationship between the pandemic and alcohol consumption patterns, providing insights that may be relevant to the use of this commonly consumed substance with implications relevant to long-term effects from the patterns observed.

Measurement of transdermal alcohol concentration using a wrist-wornenzymatic transdermal monitor.

New-generation transdermal monitors such as the ION Research Alpha Prototypes (ION RAP) hold promise for real-time alcohol measurement, with improvements in design features such as sampling frequency, size, and comfort. This paper aims to provide the first comparisons of the wrist-worn enzyme-based ION RAP and the fuel cell-based SCRAM-CAM against breath alcohol concentration (BrAC) readings. Participants (N=23) completed a total of 69 laboratory alcohol administration sessions while wearing both a prototype of the ION RAP wristband and a SCRAM-CAM ankle monitor; they also gave breath samples each 10min. Analyses focused on latencies of transdermal alcohol concentration (TAC) after alcohol ingestion, correlations, and cross-correlations between BrAC and TAC measurements. A high failure rate of the ION RAP was observed (61.5% of the sessions were excluded due to the sessions not containing enough valid data). On average, the SCRAM-CAM and ION RAP detected alcohol 43 (SD=21) and 50 (SD=27) minutes after the first drink, with peak values reached after 138 (SD=47) and 154 (SD=56) minutes, respectively. SCRAM-CAM TAC peak (r=0.185, p=0.375) and area under the curve (AUC; r=0.320, p=0.118) showed small- and medium-sized correlations to BrAC. ION RAP TAC peak (r=-0.082, p=0.698) and AUC (r=0.040, p=0.852) correlations to BrAC were close to zero. In this study, the new-generation ION RAP and the traditionally used SCRAM-CAM show similar delays in detection and similar TAC curves over time, despite using either enzyme- or fuel cell-based technologies, respectively. Due to high failure rates of the ION RAP prototypes and close to zero correlations to BrAC, further developments and improvements of these TAC wristbands are required for reliable and valid use in real-time alcohol measurement.

Alcohol binge-drinking damage on the vestibulo-oculomotor reflex.

Binge drinking is associated with several adverse effects in multiple organs. This study aimed at evaluating the effects of a binge-like-drinking on the vestibulo-oculomotor reflex (VOR) using the video Head Impulse Test (vHIT) and the functional Head Impulse Test (fHIT). Eleven healthy men (age range 32-35years) with moderate drinking habits and no history of vestibular dysfunction were enrolled. A preliminary assessment of breath alcohol concentration (BrAC) to check for zero alcohol value and a pre-intake evaluation of VOR using the vHIT and the fHIT were carried on. Then, the subjects were asked to take drinks with different alcohol content (8-40% ethanol by volume) according to their choice, consuming at least 5 standard drinks. Volunteers stopped drinking after 3h. After a further 30min, post-intake BrAC measurements and VOR analysis were repeated. After alcohol intake, vHIT recorded an overall significant reduction of VOR gain (0.82 ± 0.07 on both sides) although the outcomes were below the normal range only in the four subjects with the highest blood alcohol levels. The post-intake fHIT outcomes were substandard in 9 participants, with a significant deterioration in performance (% of exact answers = 84.54 ± 11.05% on the left, 83.18 ± 14.53 on the right). Binge drinking severely affects VOR; fHIT seems more sensitive than vHIT in the assessment of VOR function for complex vestibular lesions, such as those determined by ethanol, suggesting that fHIT could support vHIT in vestibular dysfunction assessment.

The alcohol breath test in practice: effects of exhaled volume.

Alcohol breath test (ABT) measurements are sensitive to the volume of the exhaled breath. Although a minimum breath volume is required for a legally acceptable sample, any additional increase in the volume of exhaled air increases the measurement of breath alcohol concentration (BrAC). Using a sample of 115 ABTs collected by police agencies for evidentiary purposes, we studied the influence of exhaled air volume on the measurement of BrAC. The 115 ABTs were performed on 30 different Alcotest 9510s. Each of the tests included paired, time series measurements of exhaled breath flow rates and breath alcohol content. The exhalation flow rates and exhalation times were used to create exhalation volume-BrAC plots. On average, exhaled air volumes were ~50% of the subjects' age-, height-, race-, and sex-predicted vital capacities (VC). More than 80% of the samples had exhaled air volumes ranging between 30 and 70% of the subject's predicted VC. Breath volumes for duplicate breath samples were similar. For all breath samples, BrAC increased with exhalation volume, an expected behavior for any very high blood solubility compound such as alcohol. Beyond the legally accepted minimum expiratory volume, BrAC increased, on average, at a rate of 9.2 ± 2.8%/liter air exhaled. As a result, a person who exhales just beyond the minimum volume will have a lower BrAC compared with a person who exhales a full VC. Exhaled volume materially impacts the measurement of an ABT. NEW & NOTEWORTHY Subjects who provide breath samples for evidentiary alcohol breath tests exhale, on average, about half of their predicted vital capacity. Because breath alcohol concentration increases with greater exhaled air volume, subjects who exhale more than average volume will have a greater breath alcohol concentration, whereas subjects who exhale less than average volume will have a lesser breath alcohol concentration. A quantification of air volume impact on breath alcohol concentration is provided.

Strictly conservative expected values in the case of heteroscedastic errors and their application to evidential breath alcohol confidence intervals for concentration measurements

AbstractIn this study, 2 different methods for determining strictly conservative confidence intervals for expected values in the case of heteroscedastic errors are presented. A conservative confidence interval means that a given false positive error rate is not exceeded. The novelty in both approaches is in carrying out the required approximations in such a way that this property holds. The other method is based on variance stabilizing transformations and given as 2 variants, Transformation Models I and II. For variant II, a rigorous proof is given to show that a given false positive error rate is not exceeded if the underlying distributional assumptions are valid. The second method is based on modeling the variance as a function of the expected value, and this is also given as 2 variants, Variance Models I and II. In all cases, only random errors are considered. The methods were tested and compared by applying them to a real case of breath alcohol concentration measurements performed by the Finnish law enforcement authorities, and also by simulation studies. The methods compared were studied by simulating a sample that had the same distributional properties as the real data. These studies showed that Variance Model I is overly conservative, and Variance Model II doesn't quite satisfy the set rate. Both transformation models give too many false positives at concentrations levels exceeding the prosecution limits, but in the range of prosecution limits they could be used.

Alcohol Exposure Rate Control Through Physiologically Based Pharmacokinetic Modeling

The instantaneous rate of change of alcohol exposure (slope) may contribute to changes in measures of brain function following administration of alcohol that are usually attributed to breath alcohol concentration (BrAC) acting alone. To test this proposition, a 2-session experiment was designed in which carefully prescribed, constant-slope trajectories of BrAC intersected at the same exposure level and time since the exposure began. This paper presents the methods and limitations of the experimental design. Individualized intravenous infusion rate profiles of 6% ethanol (EtOH) that achieved the constant-slope trajectories for an individual were precomputed using a physiologically based pharmacokinetic model. Adjusting the parameters of the model allowed each infusion profile to account for the subject's EtOH distribution and elimination kinetics. Sessions were conducted in randomized order and made no use of feedback of BrAC measurements obtained during the session to modify the precalculated infusion profiles. In one session, an individual's time course of exposure, BrAC(t), was prescribed to rise at a constant rate of 6.0 mg% per minute until it reached 68 mg% and then descend at -1.0 mg% per minute; in the other, to rise at a rate of 3.0 mg% per minute. The 2 exposure trajectories were designed to intersect at a BrAC (t = 20 minutes) = 60 mg% at an experimental time of 20 minutes. Intersection points for 54 of 61 subjects were within prescribed deviations (range of ± 3 mg% and ± 4 minutes from the nominal intersection point). Results confirmed the feasibility of applying the novel methods for achieving the intended time courses of the BrAC, with technical problems limiting success to 90% of the individuals tested.

Preparation of calibration gas mixtures for the measurement of breath alcohol concentration

Calibration gas mixtures for breath alcohol measuring techniques need to have a defined ethanol concentration in water-saturated air. For the calibration of evidential breath analysers in Germany, these gases are prepared at the Physikalisch-Technische Bundesanstalt according to the saturation method. The ethanol concentration is calculated via the air–liquid partition ratios of the air–water–ethanol substance system. This article deals with the selection and critical consideration of different preparation methods for test gases and their applicability to the specific gas mixture required for breath alcohol measurements.

Influence from breathing pattern on alcohol and tracer gas expirograms—Implications for alcolock use

Measurement of breath alcohol concentration is strongly influenced by timing and the breathing pattern. In particular, shallow expiration and hyperventilation leads to underestimation of the breath alcohol concentration. In the present study, expirograms of alcohol, water and carbon dioxide were recorded in 30 healthy individuals at various breathing manoeuvres (tidal volume, slow maximum and vital capacity expiration, breath holding, and hyperventilation). Estimation of the end expiratory alcohol concentration with the use of simultaneously measured carbon dioxide was shown to reverse the tendency of underestimation at shallow expiration and hyperventilation. These findings indicate that breath alcohol estimations can be performed at shorter expiration time and reduced expired volume compared to existing alcolocks. This is believed to improve their usability and to prevent a possible route for manipulation.

A study concerning the blood/breath alcohol conversion factor Q: Concentration dependency and its applicability in daily routine

The conversion factor Q, obtained by division of blood alcohol concentration (BAC) by breath alcohol concentration (BrAC) is a widely discussed topic due to its great variance. By Austrian law, regulations frequently require an estimation of a corresponding BAC by a measured BrAC. It is known that Q depends among other things, on the alcohol kinetic state of the person being tested, which mathematically can be transformed to a dependency on the BrAC. Theoretically calculated Q values per BrAC level form a hyperbola shaped curve, thus decreasing with increasing BrAC values. Applying Austrian forensic standards for BAC and BrAC measurements, these calculations were verified in a study under practical conditions with BAC and BrAC data of 390 individuals. Q decreases from 2629 (±455) for BrAC levels <0.1 mg/l to 2229 (±160) for a BrAC range of 0.4–0.5 mg/l and increases again to 2428 (±124) for BrAC levels >0.6 mg/l. Since these results were obtained under realistic practical conditions they can be directly applied in routine forensic expert opinion and can eliminate avoidable variances in the calculation of Q.

Comparative regression analysis of concurrent elimination-phase blood and breath alcohol concentration measurements to determine hourly degradation rates

Following the introduction of limit values for blood alcohol and breath alcohol concentrations of 0.5 g/kg and 0.25 mg/L, respectively, as provided under s. 24 a of the German Road Traffic Act the question is whether also breath alcohol concentrations can be back calculated to the time of the traffic offence in cases where it is definite that the person to be examined is in the period of alcohol elimination. To this end, a study was performed in which 56 healthy volunteers consumed 0.5, 0.8 and 1.0 g of ethanol mixed with fruit juice per kilogram of body weight over a period of 10–20 min. Calculations included all 391 pairs of concurrent blood alcohol and breath alcohol concentration values obtained after 2 h following the end of drinking. All volunteers exceeded the peak value of the alcohol curve. The measured values included were above 0.1 g/kg and 0.05 mg/L. For an average intake of alcohol of 0.88 g/kg the following regression lines were calculated for the period starting 2 h after the end of drinking: blood alcohol concentration [g/kg]=1.318−0.172 h and breath alcohol concentration [mg/L]=0.589−0.079 h. Subtracting the simple standard deviation from the mean value yielded hourly degradation rates above 0.1 g/kg and above 0.05 mg/L, respectively. Subtracting two standard deviations, the values fell below this level in both cases. In fact, back calculation of breath alcohol concentrations based on 0.05 mg/h seems to be possible for traffic offences if certain conditions are complied with, such as the use of Evidential 7110, a calibrated breath alcohol analyser approved by the Federal Physical–Technical Laboratory for measuring the breath alcohol concentration.

Capacitive porous silicon sensors for measurement of low alcohol gas concentration at room temperature

Capacitive alcohol gas sensors using a porous silicon (PS) layer were fabricated and investigated for the measurement of breath alcohol concentration. Since the PS layer shows high adsorption against ethanol along with a large internal surface area, detecting low alcohol gas concentrations without any heating may be realized in comparison with metal oxide sensors. In this work, we measured the capacitance for the range of 0–0.5% alcohol concentrations using the proposed sensors, and observed how illumination of UV light affected the sensitivity. In addition, the effect of CO2 and N2 gases involved commonly in exhaling breath was estimated, and the same experiment for methanol gas was executed to compare qualitatively with ethanol gas.

A Physiologically‐Based Pharmacokinetic (PBPK) Model for Alcohol Facilitates Rapid BrAC Clamping

Alcohol clamping is a technique that maintains a constant breath alcohol concentration (BrAC) for prolonged intervals, thereby reducing experimental variance in the time course of organ exposure to alcohol, when compared with oral alcohol administration paradigms. The technique employs an intravenous (i.v.) infusion of an ethanol solution at a rate that is intermittently adjusted based on real-time BrAC measurements. In earlier studies, when the clamped state was induced with an oral ethanol loading dose, the vagaries of gastric emptying and absorption were associated with a 45 min delay (RST: reliable start time) before collection of dependent measurements could be planned with confidence. The objective of the present study was to develop an induction method that provides an earlier RST, and to compare the performance of the two methods. The "quick-clamping" method replaced the oral loading dose with a preprogrammed infusion rate profile. A three-compartment physiologically-based pharmacokinetic (PBPK) model for ethanol was constructed, then tailored to each subject using individualized estimates of model parameters. The model was used to compute the infusion-rate profile that would produce the desired time course of BrAC when infused in the corresponding subject. The two clamping methods were compared in a two-session crossover study in 20 healthy young subjects (10 males, 10 females). Compared with the oral/i.v. method, quick clamping produced a comparable precision in the control of BrACs during the clamped interval, and provided a much earlier RST (mean +/- SE for quick-clamp: 17 +/- 4 min; for oral/i.v. clamp: 45 +/- 7 min). The quick-clamping method enables, for the first time, the examination of the early-phase neuroadaptive responses to alcohol in human subjects.

The alcohol breath test--a review.

The alcohol breath test (ABT) is evaluated for variability in response to changes in physiological parameters. The ABT was originally developed in the 1950s, at a time when understanding of pulmonary physiology was quite limited. Over the past decade, physiological studies have shown that alcohol is exchanged entirely within the conducting airways via diffusion from the bronchial circulation. This is in sharp contrast to the old idea that alcohol exchanges in the alveoli in a manner similar to the lower solubility respiratory gases (O2 and CO2). The airway alcohol exchange process is diffusion (airway tissue) and perfusion (bronchial circulation) limited. The dynamics of airway alcohol exchange results in a positively sloped exhaled alveolar plateau that contributes to considerable breathing pattern-dependent variation in measured breath alcohol concentration measurements.

Acute and chronic alcohol tolerance in humans: effects of dose and consecutive days of exposure.

Male social drinkers received doses of either 0.75 or 1.0 g/kg body weight of alcohol over 5 consecutive days. The beverage was divided into three equal drinks, and subjects performed an eye-hand coordination motor task after each drink. The breath alcohol concentration (BAC) was assessed at each performance measurement period. Performance was also assessed when the BAC level on the descending limb of the BAC curve was similar to each of the three BAC measurements on the ascending curve. Each group developed chronic tolerance (comparing the daily postalcohol performance with the daily prealcohol performance) by the 4th day of exposure. The development of a degree of acute tolerance (assessed by comparing the performance on the ascending and descending limbs of the BAC curve) was not observed consistently in the 1.0 g/kg dose group, but was seen in more than half of the subjects in the 0.75 g/kg dose group by the 4th and 5th day of exposure.

Blood and Breath Alcohol Concentration Measurements Are Typically Invalid Indicators of Intoxication and Impairment

Opinions about alcohol intoxication and impairment are often invalid when based on blood alcohol concentration (BAC) or breath alcohol concentration (BrAC), particularly when BAC is converted from BrAC. This paper discusses serious problems in measuring alcohol concentrahon that substance abuse counselors should consider when formulating opinions using BAC or BrAC.

Applying a data acquisition system to the analysis of breath alcohol profiles

A breath alcohol profile is generated as a continuous function of time while a person is providing a breath sample. This paper describes a data acquisition system which samples breath alcohol concentrations at discrete intervals during exhalation. The data are stored on disk for later analysis. It is shown that the area under the profile curve for samples preceded by breath-holding is significantly larger than when breathing is normal prior to sample provision (p less than 0.001). The differences between the breath alcohol concentration measurements are also statistically significant (p less than 0.001) for the two different breathing patterns prior to breath exhalation. These results have physiological implications and suggest another means of evaluating breath alcohol profiles.

Accuracy and precision of breath alcohol measurements for subjects in the absorptive state.

Published data are analyzed in order to estimate the accuracy of breath-alcohol measurements for subjects during absorption of orally ingested ethanol. Simultaneous measurements of breath alcohol concentration (BrAC) and venous blood alcohol concentration (VBAC) show that actual VBAC can be overestimated by more than 100% for a significant amount of time after drinking stops. The maximum error found for four individual subjects is +230%, +190%, +60%, and +30%. The magnitude of these errors indicates that results from quantitative evidential breath alcohol analyzers are far less accurate for the absorptive state than they are during the postabsorptive state, but the specifications for accuracy and precision given by manufacturers of these instruments do not reflect this. The results also indicate that there is a significant likelihood that subjects will be in the absorptive state when tested under field conditions. I conclude that estimates of BAC based on BrAC measurements are not reliable in the absorptive state and that the uncertainty associated with such estimates should be accounted for, particularly when the results are used in connection with law enforcement.

Electrochemical measurement of breath-alcohol concentration: precision and accuracy in relation to blood levels

This paper deals with the precision and accuracy of an electroanalytical device (Alcolmeter AE-D1) used for the determination of alcohol in human breath. Experiments were made under in vitro conditions with air-ethanol vapour mixtures and in vivo with human volunteers after they consumed alcohol. The standard deviation (SD) of single determinations of ethanol in breath or standard vapour increased with increase in the concentration in the samples. At a mean concentration of about 50 mg/dl blood ethanol equivalent, the sd in vitro was 1.5 mg/dl and in vivo 1.6 mg/dl. The blood and breath concentration-time profiles were well-matched after ethanol intake of 0.54, 0.72 and 0.90 g/kg body wt. The regression equation relating breath instrument reading ( y) with blood alcohol ( x) was y = −0.20 + 0.93 x. The y intercept was not significantly different from zero and the correlation coefficient was 0.98. The breath alcohol determinations were, however, more variable at higher levels of blood-ethanol and the results were therefore evaluated with log transformations. The regression equation now became y = 0.91 x with 95% confidence limits of y = 0.72 x and y = 1.16 x. For unbiased estimates of blood-ethanol concentration the instrument should be calibrated with a blood/breath ethanol ratio of 2,300:1.