Laboratory evaluation of a new evidential breath-alcohol analyser designed for mobile testing--the Evidenzer

Forensic perspective of detecting ethanol with a breath analyser

Breathalysers are commonly employed to diagnose drunk drivers but their ability to accurately measure levels of ethanol will depend on a number of variables, including the instrument's quality, environmental temperature, pattern of respiration, the consumption of food and drugs, pathological condition, metabolic state, and mouth alcohol. This article will consider how these factors affect results and provides suggestions on how to improve the test's admissibility in evidence.

Assessment of the breath alcohol concentration in emergency care patients with different level of consciousness

BACKGROUND

Many patients seeking emergency care are under the influence of alcohol, which in many cases implies a differential diagnostic problem. For this reason early objective alcohol screening is of importance not to falsely assign the medical condition to intake of alcohol and thus secure a correct medical assessment.

OBJECTIVE

At two emergency departments, demonstrate the feasibility of accurate breath alcohol testing in emergency patients with different levels of cooperation.

METHOD

Assessment of the correlation and ratio between the venous blood alcohol concentration (BAC) and the breath alcohol concentration (BrAC) measured in adult emergency care patients. The BrAC was measured with a breathalyzer prototype based on infrared spectroscopy, which uses the partial pressure of carbon dioxide (pCO₂) in the exhaled air as a quality indicator.

RESULT

Eighty-eight patients enrolled (mean 45 years, 53 men, 35 women) performed 201 breath tests in total. For 51% of the patients intoxication from alcohol or tablets was considered to be the main reason for seeking medical care. Twenty-seven percent of the patients were found to have a BAC of <0.04 mg/g. With use of a common conversion factor of 2100:1 between BAC and BrAC an increased agreement with BAC was found when the level of pCO₂ was used to estimate the end-expiratory BrAC (underestimation of 6%, r = 0.94), as compared to the BrAC measured in the expired breath (underestimation of 26%, r = 0.94). Performance of a forced or a non-forced expiration was not found to have a significant effect (p = 0.09) on the bias between the BAC and the BrAC estimated with use of the level of CO₂. A variation corresponding to a BAC of 0.3 mg/g was found between two sequential breath tests, which is not considered to be of clinical significance.

CONCLUSION

With use of the expired pCO₂ as a quality marker the BrAC can be reliably assessed in emergency care patients regardless of their cooperation, and type and length of the expiration.

Study I: effects of 0.06% and 0.10% blood alcohol concentration on human postural control

Alcohol intoxication causes many accidental falls presented at emergency departments, with the injury severity often related to level of blood alcohol concentration (BAC). One way to evaluate the decline in postural control and the fall risk is to assess standing stability when challenged. The study objective was to comprehensively investigate alcohol-related impairments on postural control and adaptive motor learning at specific BAC levels. Effects of alcohol intoxication at 0.06% and 0.10% BAC were examined with posturography when unperturbed or perturbed by calf vibration. Twenty-five participants (mean age 25.1 years) were investigated standing with either eyes open or closed. Our results revealed several significant findings: (1) stability declined much faster from alcohol intoxication between 0.06% and 0.10% BAC (60-140%) compared with between 0.0% and 0.06% BAC (30%); (2) sustained exposure to repeated balance perturbations augmented the alcohol-related destabilization; (3) there were stronger effects of alcohol intoxication on stability in lateral direction than in anteroposterior direction; and (4) there was a gradual degradation of postural control particularly in lateral direction when the balance perturbations were repeated at 0.06% and 0.10% BAC, indicating adaptation deficits when intoxicated. To summarize, alcohol has profound deteriorating effects on human postural control, which are dose dependent, time dependent and direction specific. The maximal effects of alcohol intoxication on physiological performance might not be evident initially, but may be revealed first when under sustained sensory-motor challenges.

Blood alcohol concentration at 0.06 and 0.10% causes a complex multifaceted deterioration of body movement control

Alcohol-related falls are recognized as a major contributor to the occurrence of traumatic brain injury. The control of upright standing balance is complex and composes of contributions from several partly independent mechanisms such as appropriate information from multiple sensory systems and correct feedback and feed forward movement control. Analysis of multisegmented body movement offers a rarely used option for detecting the fine motor problems associated with alcohol intoxication. The study aims were to investigate whether (1) alcohol intoxication at 0.06 and 0.10% blood alcohol concentration (BAC) affected the body movements under unperturbed and perturbed standing; and (2) alcohol affected the ability for sensorimotor adaptation. Body movements were recorded in 25 participants (13 women and 12 men, mean age 25.1 years) at five locations (ankle, knee, hip, shoulder, and head) during quiet standing and during balance perturbations from pseudorandom pulses of calf muscle vibration over 200s with eyes closed or open. Tests were performed at 0.00, 0.06, and 0.10% BAC. The study revealed several significant findings: (1) an alcohol dose-specific effect; (2) a direction-specific stability decrease from alcohol intoxication; (3) a movement pattern change related to the level of alcohol intoxication during unperturbed standing and perturbed standing; (4) a sensorimotor adaptation deterioration with increased alcohol intoxication; and (5) that vision provided a weaker contribution to postural control during alcohol intoxication. Hence, alcohol intoxication at 0.06 and 0.10% BAC causes a complex multifaceted deterioration of human postural control.

Breath alcohol analysis incorporating standardization to water vapour is as precise as blood alcohol analysis

A novel breath-alcohol analyzer based on the standardization of the breath alcohol concentration (BrAC) to the alveolar-air water vapour concentration has been developed and evaluated. The present study compares results with this particular breath analyzer with arterial blood alcohol concentrations (ABAC), the most relevant quantitative measure of brain alcohol exposure. The precision of analysis of alcohol in arterial blood and breath were determined as well as the agreement between ABAC and BrAC over time post-dosing. Twelve healthy volunteers were administered 0.6g alcohol/kg bodyweight via an orogastric tube. Duplicate breath and arterial blood samples were obtained simultaneously during the absorption, distribution and elimination phases of the alcohol metabolism with particular emphasis on the absorption phase. The precision of the breath analyzer was similar to the determination of blood alcohol concentration by headspace gas chromatography (CV 2.40 vs. 2.38%, p=0.43). The ABAC/BrAC ratio stabilized 30min post-dosing (2089±99; mean±SD). Before this the BrAC tended to underestimate the coexisting ABAC. In conclusion, breath alcohol analysis utilizing standardization of alcohol to water vapour was as precise as blood alcohol analysis, the present "gold standard" method. The BrAC reliably predicted the coexisting ABAC from 30min onwards after the intake of alcohol.

Alcohol intoxication at 0.06 and 0.10% blood alcohol concentration changes segmental body movement coordination

Alcohol intoxication is the cause of many falls requiring emergency care. The control of upright standing balance is complex and comprises contributions from several partly independent mechanisms like coordination, feedback and feedforward control and adaptation. Analysis of the segmental body movement coordination offers one option to detect the severity of balance problems. The study aims were (1) to investigate whether alcohol intoxication at 0.06 and 0.10% blood alcohol concentration (BAC) affected the segmental movement pattern under unperturbed and perturbed standing; (2) whether alcohol affected the ability for movement pattern adaptation; (3) whether one's own subjective feeling of drunkenness correlated to the movement pattern used. Twenty-five participants (13 women and 12 men, mean age 25.1 years) performed tests involving alcohol intoxication. Body movements were recorded at five locations (ankle, knee, hip, shoulder and head) during quiet standing and pseudorandom pulses of calf muscle vibration for 200 s with eyes closed or open. There was no significant effect of alcohol on the general movement pattern in unperturbed stance or on adaptation. However, when balance was repeatedly perturbed, knee movements became significantly less correlated to other body movements over time at 0.10% BAC and when visual information was unavailable, suggesting that the normal movement pattern could not be maintained for a longer period of time while under 0.10% BAC intoxication. Subjective feelings of drunkenness correlated often with a changed upper body movement pattern but less so with changed knee movements. Thus, an inability to relate drunkenness with changed knee movements may be a contributing factor to falls in addition to the direct effect of alcohol intoxication.

Methodology investigation of expirograms for enabling contact free breath alcohol analysis

The present techniques for breath alcohol determination have usability limitations concerning practical use and the time and effort required for the test person. The rationale of the physiological assumptions in a recently demonstrated technique for breath analysis without a mouthpiece is investigated in this paper. Expirograms quantifying ethanol, carbon dioxide (CO(2)) and water (H(2)O) from 30 test subjects were analysed, with respect to the influence of individual variations in end-expiratory CO(2) and H(2)O concentrations, and possible benefits from simultaneous measurement of CO(2) or H(2)O. Both healthy subjects and patients suffering from pulmonary diseases performed breath tests with small and maximum volume expiration. The breath tests were recorded basically with a standard evidential instrument using infrared absorption spectroscopy, and equipped with a mouthpiece. Average concentrations were significantly higher for the maximum than for the small expirations. For the maximum expirations, the healthy subjects had a significantly higher end-expired PCO(2) of 4.4 ± 0.5 kPa (mean ± standard deviation) than the patients (3.9 ± 0.7 kPa). The corresponding values for H(2)O were 39 ± 1 and 38 ± 1 mg l(-1). The results indicate that the CO(2) variability is consistent with the requirements of accuracy for alcohol ignition interlocks. In addition, CO(2) as tracer gas is preferable to H(2)O due to its low concentration in ambient air. In instruments for evidential purposes H(2)O may be required as tracer gas for increased accuracy. Furthermore, the study provides support for early determination of breath alcohol concentration, indicating that determination after 2 s will introduce an additional random error of 0.02 mg l(-1) or less.

Increased visual dependence and otolith dysfunction with alcohol intoxication

Alcohol intoxication affects the vestibular system and balance control in many ways. We have investigated how acute, moderate (blood alcohol concentrations of 0.06+/-0.01%), and high (0.10+/-0.02%) alcohol intoxication affects the ability to perceive the visual horizontal and vertical and the visual field dependence measured with the rod and frame tests in 24 healthy participants. Alcohol ingestion impaired the ability to use gravitational vestibular cues when determining the visual vertical and horizontal, and caused increased visual field dependence. With conflicting gravitational and visual information, alcohol seems to promote a reweighting in balance control from a vestibular to a more visual dependency. Furthermore, the results indicate that alcohol intoxication at these levels start instigating a decompensation of minute subclinical vestibular asymmetries.

Breath alcohol concentration determined with a new analyzer using free exhalation predicts almost precisely the arterial blood alcohol concentration

A new breath alcohol (ethanol) analyzer has been developed, which allows free exhalation, standardizes measured exhaled alcohol concentration to fully saturated water vapor at a body temperature of 37 degrees C (43.95 mg/L) and includes a built-in self-calibration system. We evaluated the performance of this instrument by comparing standardized alcohol concentration in freely expired breath (BrAC) with arterial (ABAC) and venous (VBAC) blood alcohol concentrations in fifteen healthy volunteers who drank 0.6 g of alcohol per kg body weight. The precision (coefficient of variation, CV) of the analyzer based on in vivo duplicate measurements in all phases of the alcohol metabolism was 1.7%. The ABAC/BrAC ratio was 2251+/-46 (mean+/-S.D.) in the post-absorptive phase and the mean bias between ABAC and BrAC x 2251 was 0.0035 g/L with 95% limits of agreement of 0.033 and -0.026. The ABAC and BrAC x 2251 were highly correlated (r=0.998, p<0.001) and the regression relationship was ABAC = 0.00045 + 1.0069 x (BrAC x 2251) indicating excellent agreement and no fixed or proportional bias. In the absorption phase, ABAC exceeded BrAC x 2251 by at most 0.04+/-0.03 g/L when tests were made at 10 min post-dosing (p<0.05). The VBAC/BrAC ratio never stabilized and varied continuously between 1834 and 3259. There was a proportional bias between VBAC and BrAC x 2251 (ABAC) in the post-absorptive phase (p<0.001). The pharmacokinetic analysis of the elimination rates of alcohol and times to zero BAC confirmed that BrAC x 2251 and ABAC agreed very well with each other, but not with VBAC (p<0.001). We conclude that this new breath analyzer using free exhalation has a high precision for in vivo testing. The BrAC reflects very accurately ABAC in the post-absorption phase and substantially well in the absorption phase and thereby reflects the concentration of alcohol reaching the brain. Our findings highlight the magnitude of arterio-venous differences in alcohol concentration and support the use of breath alcohol analyzers as a stand-alone test for medical and legal purposes.

Driving under the influence of chlormethiazole

This article describes a case of driving under the influence of the sedative-hypnotic-anticonvulsant drug chlormethiazole. The suspect, who was a physician, was driving dangerously on a busy highway and caused a traffic collision. When apprehended by the police, the man had bloodshot and glazed eyes and pupil size was enlarged. He could not answer the questions properly and his gait was unsteady. A roadside breath-alcohol screening test was positive but an evidential breath-alcohol test conducted about one hour later was below the legal limit for driving of 0.10 mg/L (10 microg/100 mL or 0.021 g/210 L). Because of the special circumstances of the traffic crash and the man's appearance and behaviour, the police suspected that drugs other than alcohol were involved and obtained a venous blood sample for toxicological analysis. The blood contained 0.23 mg/g alcohol, which is above the legal limit for driving in Sweden 0.20 mg/g (20 mg/100 mL or 0.020 g/100 mL), and codeine was also present at a therapeutic concentration of 0.02 mg/L. The conflict between the clinical signs of impairment and the toxicology report prompted a reanalysis of the blood sample with major focus on sedative-hypnotic drugs. Analysis by capillary GC-NPD identified chlormethiazole at a concentration of 5mg/L, the highest so far encountered in traffic cases in Sweden. In 13 other impaired driving cases over 10 years the mean (median) and range of concentrations of chlormethiazole were 1.6 mg/L (1.6 mg/L) and 0.3-3.3 mg/L. This case report underscores the need to consider clinical observations and the person's behaviour in relation to the toxicology report when interpreting and testifying in drug-impaired driving cases.