In vivo evaluation of BACtrack® Skyn™: a discrete wrist-worn transdermal alcohol monitoring device marketed to the public

A discrete wrist-worn transdermal alcohol monitoring device, the BACtrack® Skyn™, was evaluated in a subject over three drinking sessions. The relationship between transdermal alcohol concentration (TAC) and breath alcohol concentration (BrAC) was evaluated. The relationship amongst contemporaneous TAC/BrAC measurements revealed an R of 0.65, while the relationship in the 45-minute post-drinking phase revealed an R of 0.89. Results obtained show promise for its use. Further research is needed with many subjects in real-world drinking situations.

In vivo evaluation of BACtrack® Skyn™: a discrete wrist-worn transdermal alcohol monitoring device marketed to the public

A discrete wrist-worn transdermal alcohol monitoring device, the BACtrack® Skyn™, was evaluated in a subject over three drinking sessions. The relationship between transdermal alcohol concentration (TAC) and breath alcohol concentration (BrAC) was evaluated. The relationship amongst contemporaneous TAC/BrAC measurements revealed an R of 0.65, while the relationship in the 45-minute post-drinking phase revealed an R of 0.89. Results obtained show promise for its use. Further research is needed with many subjects in real-world drinking situations.

P005 The effect of alcohol on the motor control of the genioglossus muscle

Rationale Alcohol is recognised to worsen snoring and obstructive sleep apnea (OSA). This effect is thought to be due to alcohol’s depressant effect on upper airway dilator muscles such as the genioglossus, but how alcohol reduces genioglossus activity is unknown. The aim of this study was to investigate alcohol’s effect on genioglossus single motor units (SMUs). Methods Healthy individuals visited the lab on two days (Alcohol: breath alcohol concentration ~0.08% or Placebo). They were instrumented with a nasal mask, 4 intramuscular genioglossus SMU EMG wires and an ear oximeter. They were exposed to 8–12 hypoxia trials (45-60s of 10%O2 followed by one breath of 100%O2) while awake. The SMUs were sorted according to their firing patterns with respect to respiration and were quantified during baseline, hypoxia, hyperoxia and recovery. Results The total number of SMUs recorded at baseline (68 and 67 respectively) and their distribution (ET: 29 vs 22, IP: 5 vs 10, IT: 8 vs 20 and TT: 26 vs 15 respectively) was similar between conditions. The discharge frequency did not differ between conditions (21Hz vs 22.4Hz, p>0.08). There was no difference between placebo and alcohol in the number (101 vs 88 respectively) and distribution (ET: 35 vs 32, IP: 22 vs 16, IT: 14 vs 22 and TT: 30 vs 17 respectively, p<0.05) of SMUs during hypoxia. Afterdischarge following hypoxia was also not different between conditions. Conclusion Alcohol has little effect on genioglossus SMUs and afterdischarge. OSA following alcohol may be related to increased upper airway resistance/nasal congestion.

Comparison of Breath and Blood Alcohol Concentrations in a Controlled Drinking Study

In this work, 114 volunteers were dosed with 80-proof liquor to produce peak blood- or breath- alcohol concentration of 0.040 to 0.080 g/100mL blood or g/210L breath. This was followed by a 30-minute deprivation period before simultaneous blood and breath samples were collected and the alcohol concentration quantified. Blood alcohol concentration was determined by gas chromatography with flame ionization detection and breath alcohol concentration by a dual-sensor Intox EC/IR II instrument. Paired Student t-tests showed that differences between paired blood and breath alcohol results differed significantly. Results from these two measurement methods are highly correlated and, on average, measured blood alcohol concentration was 11.3% greater than breath alcohol concentration. There were ten instances of breath alcohol concentration being greater than the corresponding blood alcohol concentration, and the average difference between these two values was 0.0059 g/100mL. Agreement plots of coupled blood and breath alcohol concentration revealed a mean bias of 0.00754 g/100mL and 95% limits of agreement at -0.00705 and 0.0221 g/100mL. Once breath alcohol concentration values were truncated to the hundredths place as required by Wisconsin state statute, only three participants had greater breath alcohol concentration than corresponding blood alcohol concentration, with an average difference between these values of 0.008 g/100mL. Agreement plots with truncated breath alcohol concentration values gave a mean bias of 0.0120 g/100mL and 95% limits of agreement at -0.00344 and 0.0275 g/100mL. Data showed that typically, blood samples had greater alcohol concentrations than corresponding breath values. Differences were exacerbated by Wisconsin’s statutory requirement that reported breath alcohol measurements be truncated to the hundredths place whereas blood has no corresponding mandate.

Deconvolving breath alcohol concentration from biosensor measured transdermal alcohol level under uncertainty: a Bayesian approach

<abstract><p>The posterior distribution (PD) of random parameters in a distributed parameter-based population model for biosensor measured transdermal alcohol is estimated. The output of the model is transdermal alcohol concentration (TAC), which, via linear semigroup theory can be expressed as the convolution of blood or breath alcohol concentration (BAC or BrAC) with a filter that depends on the individual participant or subject, the biosensor hardware itself, and environmental conditions, all of which can be considered to be random under the presented framework. The distribution of the input to the model, the BAC or BrAC, is also sequentially estimated. A Bayesian approach is used to estimate the PD of the parameters conditioned on the population sample's measured BrAC and TAC. We then use the PD for the parameters together with a weak form of the forward random diffusion model to deconvolve an individual subject's BrAC conditioned on their measured TAC. Priors for the model are obtained from simultaneous temporal population observations of BrAC and TAC via deterministic or statistical methods. The requisite computations require finite dimensional approximation of the underlying state equation, which is achieved through standard finite element (i.e., Galerkin) techniques. The posteriors yield credible regions, which remove the need to calibrate the model to every individual, every sensor, and various environmental conditions. Consistency of the Bayesian estimators and convergence in distribution of the PDs computed based on the finite element model to those based on the underlying infinite dimensional model are established. Results of human subject data-based numerical studies demonstrating the efficacy of the approach are presented and discussed.</p></abstract>

Circadian regulation of breath alcohol concentration

Study objectives The role of the circadian clock in regulating blood/breath alcohol levels after consuming alcohol is uncertain. Our goal was to evaluate the degree to which the circadian system regulates breath alcohol concentration (BrAC) pharmacokinetic parameters. Methods Twenty healthy adults aged 21-30 y took part in a 4-d laboratory study. A 40-h constant routine procedure was used to assess circadian rhythms. Every 4 h, participants were given a fixed oral dose of alcohol with breathalyzer measurements taken every 5 min to construct BrAC curves. Sinusoidal models were used to test for circadian variation of the peak BrAC, the time to reach peak BrAC, the absorption rate, the elimination rate, and the time for BrAC to return to zero after alcohol was ingested. Results A significant circadian rhythm was detected for group-averaged peak BrAC values and the time for BrAC to return to zero, but not other BrAC variables. Peak BrAC values were lowest in the evening near the peak of the core body temperature rhythm and nadir of the salivary cortisol rhythm. Peak BrAC values increased during the night and reached their highest levels in the morning and afternoon. The time needed for BrAC to return to zero was also longest in the late morning and afternoon. Conclusion The circadian system modulates some BrAC pharmacokinetic parameters. In normally entrained individuals, taking the same oral dose of alcohol at different times of day can result in different BrAC responses. These findings have potential implications for alcohol-related accidents and alcohol toxicity.