The measurement of breath alcohol. The laboratory evaluation of substantive breath test equipment and the report of an operational police trial

Glucose and Ethanol Detection with an Affinity-Switchable Lateral Flow Assay

The lateral flow assay (LFA) is one of the most successful analytical platforms for rapid on-site detection of target substances. This type of assay has been used in many rapid diagnoses, for example, pregnancy tests and infectious disease prevention. However, applications of LFAs for very small molecules remain a demanding challenge due to the problem of obtaining the corresponding binding partners to form sandwich complexes. In this paper, we report an affinity-switchable (AS) LFA (ASLFA) for the rapid and selective detection of hydrogen peroxide (H₂O₂), glucose, and ethanol in blood serum and urine samples. Unlike classical LFAs, which rely on the "always on" interaction between the antigen and the antibody, the working principle of ASLFA is based on the gold nanoparticle-conjugated AS biotin probe Au@H₂O₂-ASB, which can be activated by H₂O₂ for binding with the streptavidin (SA) protein. In the presence of glucose and ethanol, glucose oxidase and alcohol oxidase can react with the substrate to generate H₂O₂ and thereby activate Au@H₂O₂-ASB for binding with SA. Therefore, this ASLFA approach can be an alternative for classical glucose and ethanol detection methods in a wide variety of samples, where simple and rapid on-site detection is essential.

Reflections on variability in the blood-breath ratio of ethanol and its importance when evidential breath-alcohol instruments are used in law enforcement

Variability in the blood–breath ratio (BBR) of alcohol is important, because it relates a measurement of the blood-alcohol concentration (BAC) with the co-existing breath-alcohol concentration (BrAC). The BBR is also used to establish the statutory BrAC limit for driving from the existing statutory BAC limits in different countries. The in-vivo BBR depends on a host of analytical, sampling and physiological factors, including subject demographics, time after end of drinking (rising or falling BAC), the nature of the blood draw (whether venous or arterial) and the subject’s breathing pattern prior to exhalation into the breath analyzer. The results from a controlled drinking study involving healthy volunteers (85 men and 15 women) from three ethnic groups (Caucasians, Hispanics and African Americans) were used to evaluate various factors influencing the BBR. Ethanol in breath was determined with a quantitative infrared analyzer (Intoxilyzer 8000) and BAC was determined by headspace gas chromatography (HS-GC). The BAC and BrAC were highly correlated (r = 0.948) and the BBR in the post-absorptive state was 2 382 ± 119 (mean ± SD). The BBR did not depend on gender (female: 2 396 ± 101 and male: 2 380 ± 123, P > 0.05) nor on racial group (Caucasians 2 398 ± 124, African Americans 2 344 ± 119 and Hispanics 2 364 ± 104, P > 0.05). The BBR was lower in subjects with higher breath- and body-temperatures (P < 0.05) and it also decreased with longer exhalation times into the breath-analyzer (P < 0.001). In the post-absorptive state, none of the 100 subjects had a BBR of less than 2 100:1.

Paradigm shift for the alcohol breath test

The alcohol breath test (ABT) has been used for quantification of ethyl alcohol in individuals suspected of driving under the influence for more than 50 years. In this time, there has been little change in the concepts underlying this single breath test. The old model, which assumes that end-exhaled breath alcohol concentration is closely related to alveolar air alcohol concentration, is no longer acceptable. This paper reviews experimental research and mathematical modeling which has evaluated the pulmonary exchange processes for ethyl alcohol. Studies have shown that alcohol exchanges dynamically with the airway tissue both during inspiration and expiration. The airway tissue interaction makes it impossible to deliver air with alveolar alcohol concentration to the mouth. It is concluded that the ABT is dependent on physiological factors that need to be assessed for accurate testing.

Elimination rates of breath alcohol

Legal driving limits are set coequally with 0.5 g/L blood alcohol concentration (BAC) or 0.25 mg/L breath alcohol concentration (BrAC) in Austria as well as in other European countries. As mostly some time elapses between BrAC measurement and driving offence, a back calculation of alcohol concentrations is often required. The calculation of hourly BrAC elimination rates can thereby help to avoid unnecessary variances. A study with 59 participants was performed under social conditions. BrAC was determined with the legally accredited Alcotest 7110 MK III A every 30 min, and concomitantly venous blood samples were drawn. Five hundred and four BrAC/BAC value pairs were evaluated. The overall mean peak BrAC was calculated with 0.456 mg/L (+/-0.119 mg/L standard deviation). The mean hourly BrAC elimination rate was overall determined with 0.082 mg/L per h (0.050-0.114, 95% range). Mean rate of females (0.087 mg/L h(-1)) and the according 95% limits were statistically significantly higher than of males (mean rate 0.078 mg/L h(-1), p<0.04). Our results confirm the possibility to implement hourly BrAC elimination rates, provided that adequate statistical ranges and basic forensic scientific rules that have been set up for alcohol back calculations are observed.

Impact of Alcohol on Vestibular Function in Relation to the Legal Limit of 0.25 mg/l Breath Alcohol Concentration

The aim of this study was to investigate the effect of alcohol on sacculocollic and vestibulo-ocular reflex systems, when the breath alcohol concentration (BrAC) is close to the legal limit of 0.25 mg/l. Twenty healthy male volunteers underwent vestibular evoked myogenic potential and caloric coupled with visual suppression tests. These tests were conducted prior to imbibing alcohol at a dosage of 0.5 g/kg to achieve a peak BrAC of around 0.25 mg/l. Once the peak BrAC was reached, these tests were performed again. Predosing and postdosing analytical results were compared, as were those with BrAC levels > or = 0.25 mg/l and <0.25 mg/l. After ingesting alcohol, 36 ears (90%) showed vestibular evoked myogenic potential responses, with a significantly increased latency of peak p13. The mean slow-phase velocity of caloric nystagmus in 40 ears after dosing was significantly reduced, and that with BrAC > or =0.25 mg/l was significantly less than that with BrAC <0.25 mg/l. Likewise, the visual suppression index decreased considerably after alcohol ingestion. In conclusion, from the perspective of vestibular function, the 0.25-mg/l BrAC limit gains clinical significance, because the vestibulo-ocular reflex performance deteriorates further, when the BrAC exceeds 0.25 mg/l. However, impaired performance of sacculocollic reflex and vestibulocerebellar interaction has occurred, when the BrAC was <0.25 mg/l, suggesting that a lower legal threshold is appropriate.

Role of variability in explaining ethanol pharmacokinetics: research and forensic applications

Variability in the rate and extent of absorption, distribution and elimination of ethanol has important ramifications in clinical and legal medicine. The speed of absorption of ethanol from the gut depends on time of day, drinking pattern, dosage form, concentration of ethanol in the beverage, and particularly the fed or fasting state of the individual. During the absorption phase, a concentration gradient exists between the stomach, portal vein and the peripheral venous circulation. First-pass metabolism and bioavailability are difficult to assess because of dose-, time- and flow-dependent kinetics. Ethanol is transported by the bloodstream to all parts of the body. The rate of equilibration is governed by the ratio of blood flow to tissue mass. Arterial and venous concentrations differ as a function of time after drinking. Ethanol has low solubility in lipids and does not bind to plasma proteins, so volume of distribution is closely related to the amount of water in the body, contributing to sex- and age-related differences in disposition. The bulk of ethanol ingested (95-98%) is metabolised and the remainder is excreted in breath, urine and sweat. The rate-limiting step in oxidation is conversion of ethanol into acetaldehyde by cytosolic alcohol dehydrogenase (ADH), which has a low Michaelis-Menten constant (Km) of 0.05-0.1 g/L. Moreover, this enzyme displays polymorphism, which accounts for racial and ethnic variations in pharmacokinetics. When a moderate dose is ingested, zero-order elimination operates for a large part of the blood-concentration time course, since ADH quickly becomes saturated. Another ethanol-metabolising enzyme, cytochrome P450 2E1, has a higher Km (0.5-0.8 g/L) and is also inducible, so that the clearance of ethanol is increased in heavy drinkers. Study design influences variability in blood ethanol pharmacokinetics. Oral or intravenous administration, or fed or fasted state, might require different pharmacokinetic models. Recent work supports the need for multicompartment models to describe the disposition of ethanol instead of the traditional one-compartment model with zero-order elimination. Moreover, appropriate statistical analysis is needed to isolate between- and within-subject components of variation. Samples at low blood ethanol concentrations improve the estimation of parameters and reduce variability. Variability in ethanol pharmacokinetics stems from a combination of both genetic and environmental factors, and also from the nonlinear nature of ethanol disposition, experimental design, subject selection strategy and dose dependency. More work is needed to document variability in ethanol pharmacokinetics in real-world situations.

Within- and between-subject variations in pharmacokinetic parameters of ethanol by analysis of breath, venous blood and urine

AIMS

To evaluate the prerequisites for using ethanol dilution to estimate total body water, we studied the within- and between-subject variation in the parameter estimates of a two-compartment model for ethanol pharmacokinetics with parallel Michaelis-Menten and first-order renal elimination. Because sampling of breath might be preferable in some clinical situations the parameter estimates derived from breath and venous blood were compared.

METHODS

On two occasions, ethanol 0.4 g kg-1 was given by intravenous infusion to 16 volunteers after they had fasted overnight. The proposed model was fitted by means of nonlinear regression to concentration-time data measured in the breath, venous blood and urine during 360 min. The model contained six parameters: Vmax and Km (Michaelis-Menten elimination constants), CLd (intercompartmental distribution parameter), VC and VT (volumes of the central and tissue compartment, respectively) and CLR (renal clearance). The volume of distribution, Vss, was calculated as the sum of VC and VT.

RESULTS

The mean +/- total s.d. of the parameter estimates derived from blood data were Vmax 95 +/- 25 mg min-1, Km 27 +/- 19 mg l-1, CLd 809 +/- 232 ml min-1, VC 14.5 +/- 4.3 l, VT 21. 2 +/- 4.4 l, CLR 3.6 +/- 2.0 ml min-1 and Vss 35.8 +/- 4.3 l. The variation within subjects amounted to 3%, 9%, 21%, 21%, 17%, 26% and 2%, respectively, of the total variation. Breath samples were associated with a similar or lower variation than blood, both within and between subjects. About 1.5% of the infused ethanol was recovered in the urine.

CONCLUSIONS

The low within-subject variation of the key parameter Vss (only 2%) suggests that ethanol dilution analysed by the pharmacokinetic model applied here may be used as an index of the total body water. Breath samples yielded at least as good reproducibility in the model parameters as venous blood.

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.

Ethanol elimination-rates determined by breath analysis as a marker of recent excessive ethanol consumption

The rate of ethanol elimination was studied in two groups of men by means of an Alcotest 7010 breath analyser. The experimental group consisted of 15 skid-row alcoholics undergoing detoxification. Their median daily ethanol consumption was 211 (range 26-476) g pure ethanol during the last year. The control group was made up of 12 age-matched healthy social drinkers consuming 9 (range 4-23) g day-1 pure ethanol during the last year. The median ethanol elimination-rate in the elimination phase was 0.25 (range 0.13-0.31) g 1-1 h-1 during the detoxification period in the experimental group. This value was approximately 70% higher than in the control group (0.14(0.12-0.17) g 1-1 h-1). Some correlation was found between reported ethanol intake, and the calculated ethanol elimination-rate, as well as gamma glutamyl transferase (GGT), alanine amino transferase (ALAT), aspartate amino transferase (ASAT), glutamate dehydrogenase (GLDH), mean corpuscular volume (MCV) and HDL-cholesterol. Of these measures, ethanol elimination-rate showed highest sensitivity and efficiency for detection of ethanol consumption above the limit of 50 g per day.

Analytical toxicology

1. Major advances in analytical toxicology followed the introduction of spectroscopic and chromatographic techniques in the 1940s and early 1950s and thin layer chromatography remains important together with some spectrophotometric and other tests. However, gas- and high performance-liquid chromatography together with a variety of immunoassay techniques are now widely used. 2. The scope and complexity of forensic and clinical toxicology continues to increase, although the compounds for which emergency analyses are needed to guide therapy are few. Exclusion of the presence of hypnotic drugs can be important in suspected 'brain death' cases. 3. Screening for drugs of abuse has assumed greater importance not only for the management of the habituated patient, but also in 'pre-employment' and 'employment' screening. The detection of illicit drug administration in sport is also an area of increasing importance. 4. In industrial toxicology, the range of compounds for which blood or urine measurements (so called 'biological monitoring') can indicate the degree of exposure is increasing. The monitoring of environmental contaminants (lead, chlorinated pesticides) in biological samples has also proved valuable. 5. In the near future a consensus as to the units of measurement to be used is urgently required and more emphasis will be placed on interpretation, especially as regards possible behavioural effects of drugs or other poisons. Despite many advances in analytical techniques there remains a need for reliable, simple tests to detect poisons for use in smaller hospital and other laboratories.

Serum alcohol levels, toxicology screens, and use of the breath alcohol analyzer

The emergency physician sees a large number of patients with problems related to the ingestion of alcohol, drugs, and toxins, and must be prepared to deal with them in an efficient and cost-effective manner. This article discusses a rationale for ordering serum alcohol levels and toxicology screens, as well as use of the breath alcohol analyzer. A serum alcohol level should be reserved for patients in whom the alcohol level is necessary to confirm a diagnosis or to guide treatment. An alcohol level is indicated when alcohol use is combined with a significant alteration in mental status, multiple drug overdose, head injury, coma, major trauma, seizures, or psychosis. The breath alcohol analyzer is useful when rapid determination of alcohol levels is desired, particularly with coma or coexisting head trauma. A low or negative level in this case rapidly alerts the physician to the presence of another condition that may require additional testing. Toxicology screening should be performed when suspected drug or toxin ingestion is combined with coma, convulsions, head injury with altered mental status, unstable vital signs, alterations in acid-base or electrolyte status, or psychosis. The screen also may be used to determine the need for a specific antidote or means of increasing excretion of a toxin, or to determine the presence of a drug that should be quantified to guide management. Open communication with the laboratory and the use of rapid screening tests markedly increase the benefit of toxicology screening.

Accuracy and usefulness of a breath alcohol analyzer

We evaluated the accuracy of a hand-held breath alcohol analyzer in the rapid determination of blood alcohol levels in the emergency patient with suspected ethanol intoxication. The Alco -Sensor III breath alcohol analyzer was used to measure alcohol levels in orally and nasally obtained end-expiratory breath samples in 55 patients. These levels were compared to directly measured blood alcohol levels. The patients were categorized into cooperative and uncooperative groups. The mean oral breath alcohol level obtained was 0.187 +/- 0.100 g/dL (range, 0.000 to 0.419) while the mean serum level was 0.217 +/- 0.113 g/dL (range, 0.00 to 400). The overall correlation between these two methods of measuring blood alcohol level was strong (r = .879, P less than .001). In cooperative patients the correlation was even stronger (r = .963, P less than .001), while in uncooperative patients the correlation was less but still significant (r = .723, P = .001). Nasally obtained samples correlated well with blood levels in cooperative patients (r = .874, P less than .001), but the correlation was less strong in uncooperative persons (r = .694, P = .003). Our study indicates that the Alco -Sensor III breath alcohol analyzer is sufficiently accurate to be of use in rapidly assessing blood alcohol levels, even when a patient is unable to cooperate fully.

Breath ethyl alcohol concentration and analysis in the presence of chronic obstructive pulmonary disease

We have made continuous measurements of exhaled ethanol concentration vs volume during slow expiration in subjects with plasma ethanol concentrations up to 700 mg/L. Subjects included individuals with normal pulmonary function and those with severe chronic obstructive pulmonary disease (COPD). In addition to the measurements of breath ethanol made using a flame ionization detector, paired measurements were also made of plasma ethanol and breath ethanol using a Model 900A Breathalyser. In normal subjects, the breath ethanol concentration was found to increase continuously during expiration until the very end of the expiration when a decline in concentration was noted. In the presence of COPD the ethanol concentration/volume tracing was essentially flat during the middle portion of expiration, but many subjects showed a decrease in concentration at the end of the expiration. One subject showed a sharp rise in breath concentration at the end of expiration. The results suggest that fluctuations in the ethanol concentration are caused by variation in the ventilation/perfusion ratio of regions of the lung supplying the expirate, and that breath with ethanol in equilibrium with the plasma is not routinely obtained, especially at the end of a maximal expiration. Thus, exhaled air at the end of maximal expiration does not always provide the best, or a close, indication of the plasma (or blood) ethanol concentration. The peak breath ethanol concentrations found were, as an equivalent plasma concentration, = -25 + 0.924 X plasma ethanol, mg/L. The Breathalyser readings = -45 + 0.898 X plasma ethanol, mg/L, with a mean difference of -81 mg/L.

How breathing technique can influence the results of breath-alcohol analysis

This paper reports experiments to test how a person's breathing technique can influence the concentration of ethanol and the temperature of end-expired breath samples. The experiments were performed with healthy men after they drank a moderate dose of ethanol and the concentration of ethanol in breath was determined by gas chromatography. The results were compared with control breaths, which were deep inspirations and forced expirations of room air, analysed within 2–3 minutes of the test-breath sample. With breath-holding (30 seconds) before expiration, the concentration of ethanol increased by 15.7 ± 2.24 per cent (mean ± SE) and the temperature of breath rose by 0.6 ± 0.09°C. Hyperventilating for 20 seconds, immediately before the analysis of breath, decreased the concentrations of ethanol by 10.6 ± 1.37 per cent and the breath temperature dropped by 1.0 ± 0.22°C. Keeping the mouth closed for 5 minutes (shallow breathing) increased expired ethanol concentration by 7.3 ± 1.2 per cent and the breath temperature rose by 0.7 ± 0.14°C. After a slow (20 second) exhalation expired ethanol increased by 2.0 ± 0.71 per cent but breath temperatures remained unchanged from control tests. My results suggest that the changes in expired-ethanol concentrations are partly caused by the rise or fall in the temperature of breath. But an equally important factor is the amount of time the breath spends in contact with the mucous membranes of the upper respiratory tract. A long contact time increases the concentration of ethanol and rapid ventilation lowers it. Regardless of the breathing technique tested, the results recovered to control values immediately the subjects began breathing normally again.