Comparison of spectroscopically measured tissue alcohol concentration to blood and breath alcohol measurements

Abstract

Abstract. Alcohol testing is an expanding area of interest due to the impacts of alcohol abuse that extend well beyond drunk driving. However, existing approaches such as blood and urine assays are hampered in some testing environments by biohazard risks. A noninvasive, in vivo spectroscopic technique offers a promising alternative, as no body fluids are required. The purpose of this work is to report the results of a 36-subject clinical study designed to characterize tissue alcohol measured using near-infrared spectroscopy relative to venous blood, capillary blood, and breath alcohol. Comparison of blood and breath alcohol concentrations demonstrated significant differences in alcohol concentration ͓root mean square of 9.0 to 13.5 mg/ dL͔ that were attributable to both assay accuracy and precision as well as alcohol pharmacokinetics. A first-order kinetic model was used to estimate the contribution of alcohol pharmacokinetics to the differences in concentration observed between the blood, breath, and tissue assays. All pair-wise combinations of alcohol assays were investigated, and the fraction of the alcohol concentration variance explained by pharmacokinetics ranged from 41.0% to 83.5%. Accounting for pharmacokinetic concentration differences, the accuracy and precision of the spectroscopic tissue assay were found to be comparable to those of the blood and breath assays.

Intravenous Ethanol Infusion Decreases Human Cortical γ-Aminobutyric Acid and N-Acetylaspartate as Measured with Proton Magnetic Resonance Spectroscopy at 4 Tesla

“…Given a recent report that capillary and breath alcohol are very similar, while venous ethanol lags significantly (49), the current observations suggest that brain ethanol is determined primarily by rapid transfer from the capillary beds. Rapid perfusion is consistent with MRS measurements in rats (50) and with other measurements in organs with high blood flow, including brain (51).…”

Comparison of spectroscopically measured finger and forearm tissue ethanol concentration to blood and breath ethanol measurements

“…Similar methods for in vivo spectroscopy have been previously described. 1,2,24,30 Prior works have indicated that the pharmacokinetic differences between blood and tissue alcohol concentrations can be pronounced during the initial period following the ingestion of the alcohol dose (termed the absorption phase) relative to the descending portion of the alcohol experiment (termed the elimination phase).…”

“…The forearm device was identical in design to the device reported in previous works. 1,2 The only fundamental difference between the finger and forearm devices was the optical probe design (discussed in Sec. 2.5).…”

“…(1)] through tissue of a given optical probe design. 1,23,24 Similarly, Monte Carlo simulations were used in this work to provide insights into the differences in effective path-length between the two optical probe designs under investigation. The effective path-length is defined as:…”

“…1,2 That work showed a first order kinetic model used by other researchers to explain alcohol pharmacokinetics between arterial and venous blood [3][4][5][6] also reasonably explained the pharmacokinetic differences between forearm tissue and blood alcohol concentrations. However, the kinetic constants associated with the forearm tissue measurement were smaller in magnitude (a larger pharmacokinetic difference) than those observed when comparing blood types to each other.…”