Evaluating alleged drinking after driving--the hip-flask defence. Part 1. Double blood samples and urine-to-blood alcohol relationship

This two-part article examines the strengths and weaknesses of various ways of investigating claims of drinking alcohol after driving, commonly known as the hip-flask or glove-compartment defence. In many countries the onus of proof in hip-flask cases rests on the prosecution. With good co-operation from the police and timely sampling of body fluids, such as blood and urine for forensic analysis of ethanol, useful evidence can be mustered to support or challenge the truthfulness of alleged drinking after driving. The person's blood-alcohol concentration (BAC) can be compared with values expected on the basis of the amount of alcohol consumed after driving, according to theoretical Widmark calculations. The actual BAC measured is then adjusted for the additional amount of alcohol consumed in the after-drink. Double blood samples, that is, taking two specimens of venous blood about 30-60 minutes apart and looking at the magnitude and direction of change in BAC provides little or no more information than a single blood specimen. However, the relationship between alcohol in blood and urine is very useful in hip-flask cases whereby the concentration expected in the primary urine is compared with the concentration in the bladder urine voided. The concentration of alcohol determined in a second urine sample collected 30-60 min later gives supporting evidence in hip-flask cases. A graphical method, which entails plotting ethanol concentrations in blood and urine as a function of time provides a robust and practical way to investigate hip-flask defences. In the second part of the review, congener analysis is presented, which entails comparing the concentrations of n-propanol, isobutanol and occasionally other congeners in the alcoholic beverage allegedly consumed after driving with the volatiles present in the suspect's blood and urine determined by headspace gas chromatography.     

Alcohol congener analysis and the source of alcohol: a review

For many decades traditional alcohol congener analysis has provided the concentrations of fermentation by-product congeners found in blood, to ascertain if the claims of an individual regarding the alcoholic beverage(s) they have consumed were feasible, assisting in cases where after-drinking is involved. However, this technique does not provide information on the exact alcoholic beverage(s) consumed. More recently, ingredient biomarker congeners specific to certain alcoholic beverages have been detected in blood, making it possible to identify the particular alcoholic beverage consumed and therefore the source of alcohol (albeit only for a limited number of beverages). This novel approach may reduce current limitations that exist with traditional methods of detecting fermentation by-product congeners, which restrict the use of alcohol congener analysis internationally and for other medico-legal scenarios. This review examines the forensic application of alcohol congener analysis in determining the source of alcohol and other techniques.     

Survey of pilots' attitudes and opinions about drinking and flying

A mailed questionnaire was used to obtain biographic, attitude, and reported behavioral data from pilots with regard to consumption of alcoholic beverages and flying. A 40.8% return of 835 mailings was obtained. Only 12 pilots reported having flown after drinking. Approximately 50% of the respondents indicated it would be safe to fly within 4 h after drinking some amount of alcoholic beverage. Based upon alcohol absorption and oxidation rates, it was estimated that 27-32% of the respondents considered flying after drinking, within a time period which would result in a 15mg% BAC or higher, to be safe behavior. Discriminant analysis showed liquor consumption and opinions regarding number of mixed drinks which could safely be consumed within 1 h before flying would correctly classify 67.5% of the respondents in terms of attitude toward drinking and flying.     

Alkoholbedingte Fahruntüchtigkeit

The judgement and evidence on offences related to alcohol impaired driving by expert witnesses essentially relates to the following areas: the analysis of blood and breath alcohol, back calculation of blood alcohol concentrations (BAC) to the time of the offence, absconding after an accident, and calculation and judgement of post-offence drinking, including congener analysis, calculation of BAC from consumption statements, judgment of relative driving inability and responsibility in case opinion on functional and metabolic alcohol tolerance, alcohol abuse and medical psychological investigation. Relevant basics of alcohol physiology (“ethanology”) and of widely accepted forensic standards are presented.     

Diagnostic meaning of urinary ethyl glucoside concentrations in relationship to alcoholic beverage consumption

Incidents and accidents often involve the drinking of alcoholic beverages. We investigated compounds that indicate the consumption of alcoholic beverages even after ethanol (EtOH) becomes undetectable in blood and urine. Ethyl glucoside (EG) has been isolated as a possible drinking marker, and a GC–MS/MS method for EG isomers has been developed. EG isomers in several alcoholic beverages were analyzed. In sake, only αEG was observed in high concentrations. In wine and beer, both α and βEG were detected. Whisky, however, did not contain EG. EtOH and EG concentrations were analyzed in urine up to 48 h after ingestion. Maximum EtOH concentrations were reached in 1–2 h and was mostly eliminated in 6 h. Maximum EG concentrations were reached in 3–6 h, gradually decreased, and remained low after 24 h. After drinking sake, the αEG concentrations were much higher than that of other alcoholic beverages. After drinking wine or beer, βEG was detected, but lower than αEG. Also, αEG was detected in urine after drinking whisky that contained no EG. This suggested that αEG may be synthesized in vivo. Disaccharide-degrading enzymes such as α-glucosidase are present in the human small intestine. It was considered that αEG was synthesized when alcohol was consumed with certain foods, such as carbohydrates. In actual forensic autopsy cases, EtOH and EG isomer analysis provided useful information regarding drinking history. In conclusion, it is considered that urinary EG isomers can be used as drinking markers that complement EtOH analysis.     

"Cognac alibi" as a drunk-driving defense and medico-legal challenge

Some drivers with positive forensic ethanol analyses, offer an explanation that they consumed alcohol a short time before a traffic accident or after driving. In medico legal practice this is commonly known as hip-flask defense, but to us as "cognac alibi" defense. In these cases, the lawyers require the medico legal experts to offer as much information as possible so that the court may come to the most reliable conclusions about the driver's blood alcohol concentration at the moment of the traffic accident (BAC(Acc)). At the Institute of Forensic Medicine our own analytical approach was established to study this medico legal problem. It consists of three inter-related phases in which it combines the obtained BAC values, with testimonies of the drunk driving suspect andalso witnesses. A specific algorithm was designed for calculating absorption and elimination of consumed alcohol. All the above-mentioned elements and blood-ethanol values calculated according to Widmark's method were inserted into appropriate cells of MS Excel software in order to calculate BAC in the function of time. The result is a relevant analysis of the drunk driving suspect's BAC in 5-minute intervals, as well as a graphic representation in chart form.     

Binge drinking, drinking and driving, and riding with a driver who had been drinking heavily among Air National Guard and Air Force Reserve Personnel

Heavy drinking is associated with significant health problems and increased risk for injury and death. Although several studies have investigated alcohol use among active duty and civilian populations, little is known about the alcohol use patterns of reserve personnel. This study examined the prevalence and correlates of binge drinking, driving after drinking, and riding in a vehicle with a driver who had consumed alcohol among 4,836 guardsmen and reservists who were taking part in basic military training (mean age = 21.3 years; 29.4% female). Forty-six percent reported one or more binge drinking episodes in the month before basic military training. Four percent drove after consuming five or more drinks, while 8.9% rode as a passenger with a driver who had been drinking heavily. Several demographic, behavioral, and attitudinal correlates of risky drinking patterns were identified. Findings have potentially important implications for the health, safety, and military readiness of reserve personnel.     

Pilots' attitudes toward alcohol use and flying

Questionnaires were sent to a national sample of licensed pilots. Respondents reported their flying experience and their drinking behavior. They also indicated the number of drinks that they believed could be safely consumed 3 hours (h) before flying or driving, and estimated the numbers of hours a person should wait, after drinking, before attempting to fly or drive. Similar questions were included regarding marijuana use. Respondents were much more conservative in their attitudes toward the use of alcohol prior to flying than prior to driving. This relationship held both for the number of drinks judged safe 3 h prior to flying or driving and for estimates of the waiting interval that would be appropriate following alcohol consumption. In addition, attitudes toward alcohol use were related to respondents' own drinking behavior, with moderate and heavy drinkers more tolerant of alcohol use in flying and driving situations than abstainers.     

In vivo proton magnetic resonance spectroscopy detection of human alcohol tolerance

Alcohol tolerance was ascertained with in vivo proton magnetic resonance spectroscopy (MRS) in men who regularly consumed either large (10–20 drinks/week) or small (2–4 drinks/week) amounts of beverage alcohol. Brain ethanol concentrations were determined by MRS, and blood ethanol levels were measured by gas chromatography after controlled ethanol administration (0.8 g/kg). Brain-blood ethanol concentration ratios for heavy drinkers were significantly greater than ratios for occasional drinkers (P < 0.002). Inasmuch as ethanol tolerance covaries with the severity of dependence, MRS procedures may facilitate our understanding of alcohol tolerance and treatment of alcoholism.     

Elevated blood ethanol levels caused by 'non-alcoholic' beer

With the availability of non-alcoholic beer, many patients are substituting non-alcoholic beer for regular beer. Moreover, several clinicians advocate the use of non-alcoholic beer by alcoholics when there is a possibility of relapse. However, patients with alcoholic end-stage liver disease can accumulate substantial circulating ethanol levels even when they consume non-alcoholic beer. We present a case of a patient with end-stage liver disease who achieved a blood alcohol level of 57 mg/dL after drinking non-alcoholic beer.     

A low right-to-left hepatic lobe ratio. Is streamlining of ethanol to the right lobe of the liver the cause?

The anterior view of a liver-spleen scintigram performed with Tc-99m sulfur colloid was used to calculate the right-to-left (R/L) hepatic lobe ratio in three patients (acute hepatitis, normal, alcoholic cirrhosis). Emission computed tomography (ECT) was also performed, and the images correlated with the data obtained from the planar images. A low R/L hepatic lobe ratio correctly identified the patient with alcoholic cirrhosis. Streamlining of ethanol to the right (R) lobe of the liver has been suggested as the principal reason why the R/L hepatic ratio is decreased in alcoholic cirrhosis. The evaluation of the ECT images, however, suggest that the count density in each lobe of the liver is similar in the patient with alcoholic cirrhosis. The latter and known information regarding the absorption of ethanol from the gastrointestinal tract are not in agreement with the alcohol streamlining theory.     

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

The Evidenzer is a new kind of forensic breath-alcohol analyser, designed for use both at a police station (stationary) and also in a police vehicle (mobile) at the roadside. In this paper we report the accuracy and precision of the Evidenzer, determined under controlled laboratory conditions. The results were compared with a well-established breath-alcohol instrument (Intoxilyzer 5000S) and also with the concentration of alcohol in venous blood. Twenty healthy volunteers (10 men and 10 women) consumed ethanol (0.4 g/kg) in 15 minutes starting two to three hours after their last meal. Venous blood and breath were obtained for determination of ethanol at 15-30 minute intervals for up to four hours post-dosing. There was a good overall agreement between the two breath-alcohol instruments and the mean bias was only 0.003 mg/L (95% limits of agreement of -0.016 to 0.023 mg/L). The standard deviation (SD) of measuring ethanol in breath was about the same for both instruments, being 0.006 mg/L, and this corresponds to a relative precision or coefficient of variation (CV) of 4.7%. When the Evidenzer was used to analyse ethanol vapour (0.50 mg/L) generated from a wet-bath simulator, i.e. in-vitro conditions, the coefficient of variation was 0.7% indicating high analytical precision. The concentration of ethanol in venous blood and breath were highly correlated (r = 0.95) although systematic differences existed depending on time after drinking when comparisons were made. Both breath-alcohol instruments gave results higher than venous blood alcohol in tests made at 15 minutes after the end of drinking whereas at all later times the venous blood-alcohol concentration was higher     

Effect of exercise and fluid consumption on salivary flow and pH

Recent claims have been made regarding the putative erosive effects of regularly ingesting low-pH beverages on the integrity of tooth enamel. The purpose of this study was to determine whether fluid consumption during exercise affects the body's defenses against enamel erosion: saliva flow and salivary pH. Males and females (n=50) exercised in the heat (26.7 degrees C, 40 % RH) for 75 min on four occasions. Within each session, subjects consumed ad-lib either water, a sports drink (Gatorade), diluted orange juice, or a homemade sports drink, with the latter three fluids all having low pH values (3.0 to 4.0). Prior to and following exercise, subjects performed a standard stimulated saliva collection procedure. Immediately following collection, saliva flow rate and pH were determined for each sample. Repeated-measures ANOVA were used to evaluate the data. Compared to pre-exercise salivary flow rates (2.6+/- 0.8 ml/min), the post-exercise rate was not different when consuming the sports drink (2.6+/- 0.9 ml/min), but decreased when water or the homemade sports drink was ingested (2.4+/- 0.9 ml/min; p<0.05). A time-by-drink interaction (p<0.05) revealed slight differences in saliva pH after exercise, depending on the beverage consumed; post-exercise saliva pH was highest for water (7.2+/- 0.2) and lowest for the homemade sports drink (7.1+/- 0.2), with the sports drink and diluted orange juice values falling in between. The results suggest that minimal changes occur in saliva pH and the rate of stimulated saliva flow with beverage consumption during exercise. Subsequent research is needed to determine whether maintenance of saliva production by drinking beverages during exercise influences the body's defenses against dental erosion via saliva production.     

Ultra-rapid rate of ethanol elimination from blood in drunken drivers with extremely high blood-alcohol concentrations

The rate of alcohol elimination from blood was determined in drunken drivers by taking two blood samples about 1 h apart. These cases were selected because the individuals concerned had reached an extremely high blood-alcohol concentration (BAC) when they were apprehended. This suggests a period of continuous heavy drinking leading to the development of metabolic tolerance. Use of double blood samples to calculate the elimination rate of alcohol from blood is valid provided that drunken drivers are in the post-absorptive phase of the BAC curve, the time between sampling is not too short, and that zero-order elimination kinetics operates. Evidence in support of this came from other drunken drivers in which three consecutive blood samples were obtained at hourly intervals. The mean BAC (N = 21) was 4.05 g/l (range, 2.71–5.18 g/l), and the average rate of alcohol elimination from blood was 0.33 g l⁻¹ h⁻¹ with a range of 0.20–0.62 g l⁻¹ h⁻¹. The possibility of ultra-rapid rates of ethanol elimination from blood in drunken drivers having extremely high BAC deserves to be considered in forensic casework, e.g., when retrograde extrapolations and other blood-alcohol calculations are made. The mechanism accounting for more rapid metabolism is probably related to induction of the microsomal enzyme (CYP2E1) pathway for ethanol oxidation, as one consequence of continuous heavy drinking. However, the dose of alcohol and the duration of drinking necessary to boost the activity of CYP2E1 enzymes in humans have not been established.     

Spectroscopic imaging of the uptake kinetics of human brain ethanol.

Previous measurements of the ratio of brain to venous blood alcohol have ranged from 21-100%, depending on the experimental model, pulse sequence, and the concentration reference used. The goal of this study was to evaluate the uptake kinetics and visibility of brain ethanol in comparison to venous blood levels using a pulse sequence that minimizes uncertainties due to differences in J-modulation, T(1), and T(2) between ethanol and the concentration standard. This was achieved using a short TE (24 msec) spin echo sequence with a semiselective refocusing pulse to minimize J-modulation losses of the ethanol. Brain ethanol levels were measured with 10-min time resolution using a 16 x 16 spectroscopic imaging matrix with nominal voxels of 1.44 cc. During the course of the study, the brain/blood alcohol ratio declined from a value of 1.54 +/- 0.74 at 35 min after drinking to a final value of 0.93 +/- 0.16 at 85 min postdrinking. Magn Reson Med 42:1019-1026, 1999.     

Measurement of direct ethanol metabolites in a case of a former driving under the influence (DUI) of alcohol offender,now claiming abstinence

A 37-year-old female subject had been convicted of driving under the influence of alcohol, and 19 months later, claimed abstinence after supervised disulfiram treatment. Our aim was to elucidate the value of direct ethanol metabolites as measures of abstinence. Ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEE) in hair, phosphatidylethanol in whole blood and EtG and ethyl sulphate in urine were measured. The results were compared with self-report of alcohol consumption and traditional blood biomarkers for chronically elevated alcohol consumption as carbohydrate deficient transferrin (CDT), gamma glutamyl transpeptidase, mean corpuscular erythrocyte volume, aspartate aminotransferase and alanine aminotransferase. EtG was found in distal parts of hair only, whereas the proximal parts were negative. Furthermore, FAEE concentrations were found in the typical distribution over the hair length and showed values typical for either moderate social drinking or abstinence. CDT was above cut-off in 9 out of 16 analyses with a decreasing tendency and the lowest values in the last 2 months before the end of sampling. The data suggest that in addition to traditional markers, a combination of direct ethanol metabolites can be useful in the expert assessment of judging driving ability. A careful individual interpretation of the results for the different markers, however, is an absolute necessity.     

Acetonaemia as an initial criterion of evaluation of a probable cause of sudden death

The archived head-space chromatograms of ethanol determinations in autopsy blood in the years 1996-2003 were analysed. One hundred and two cases with elevated acetone level >250mmol/l were selected in which the biochemical profiles of volatile alcohols (methanol, isopropanol and n-propanol) were determined after "post-hoc" calibration of the constant internal standard. Based on the files obtained from the Prosecutor's Office, the circumstances of death and those preceding death (alcoholism, prolonged or single consumption of alcohol, intoxications with other substances, hypothermia, undernourishment, diabetes) were analysed and the most probable cause of endogenous or exogenous ketonaemia were determined. All cases of unexplained deaths in alcoholics with the ethanol concentration <0.4g/l occurred after withdrawal of long-term consumption of alcohol while all alcoholics with the ethanol concentration >0.4g/l died during the so-called drinking bout. In the group of hypothermia-related deaths with ethanol concentrations <0.4g/l, the acetone concentration was statistically significantly higher than that in hypothermia group with ethanol concentration >0.4g/l in which "congeneric" concentrations of methanol and isopropanol were additionally observed. Furthermore, an algorithm of further diagnostic management was suggested to distinguish the most likely origin of acetonaemia, i.e. accumulation of exogenous "denaturants" of alcohol consumed and cases of endogenous ketogenesis.     

Nystagmus among suspected amphetamine impaired drivers

Clinical signs of drug use can be helpful to identify which drug has been consumed. Amphetamine intake has traditionally not been considered to cause nystagmus. The aim of this study was to explore whether there is a relationship between amphetamine use and nystagmus in a population of apprehended drivers in a naturalistic setting. We evaluated drivers suspected of drug-impaired driving where blood samples were collected and a clinical test of impairment (CTI) was performed. Evaluation of nystagmus is one of the CTI subtests. The samples were analysed for alcohol and psychoactive drugs. Cases with a nystagmus test were recorded and amphetamine-only cases were compared with alcohol-only cases and with cases where alcohol or drugs were not detected, respectively. Samples from 507 amphetamine-only cases were compared to 485 alcohol-only cases and 205 drug-negative cases. The median blood amphetamine concentration was 0.37 mg/L and the median alcohol concentration was 1.57 g/kg. The proportion of cases with nystagmus was similar in amphetamine-only cases (21%) and drug-negative controls (25%), p = 0.273, but higher in alcohol-only cases (53%), p < 0.001. No association was found between the blood amphetamine concentration and degree of nystagmus (Spearman's ρ = 0.008, p = 0.860), whereas an association between blood alcohol concentration and degree of nystagmus was demonstrated (ρ = 0.249, p < 0.001). In conclusion, our study did not find that apprehended drivers using amphetamine had more frequently nystagmus than a control group that tested negative for alcohol and drugs, even at high amphetamine concentrations in blood. Hence, nystagmus should not be considered a tool for identifying amphetamine-induced impairment in drivers.     

Blood analysis by headspace gas chromatography: does a deficient sample volume distort ethanol concentration?

This study was prompted by a recent judgment in the Royal Courts of Justice (Gregory v. Director of Public Prosecutions, 2002) in a case of driving a motor vehicle after consuming too much alcohol (Road Traffic Act 1988). An expert witness for the defence alleged that a deficient volume of blood in the tube sent for analysis meant an excess amount of sodium fluoride (NaF) preservative, which would increase the concentration of ethanol, determined by headspace gas chromatography (HS-GC), owing to a salting-out effect. The prosecution did not produce expert evidence to rebut this argument and the drunk driving suspect was acquitted. A small volume of blood and excess sodium fluoride might have increased the concentration of ethanol in the air-space in the tube sent for analysis but this does not mean that the result of the HS-GC analysis would be higher. This follows because prior to analysis an aliquot of blood is removed and diluted (approximately 10 times) with n-propanol as the internal standard. The dilution lowers the concentration of NaF in the blood and for quantitative analysis the ratio of the ethanol to n-propanol response is measured. The use of a ratio also helps to compensate for any salting-out effect of ethanol. Our experiments showed that a deficient volume of blood and excess NaF actually lowered the concentration of ethanol by 2-3% compared with heparinised blood. Seemingly, n-propanol (n-PrOH) a 3-carbon straight chain alcohol is salted out slightly more effectively than the 2-carbon ethanol (EtOH) causing a lower peak area ratio (EtOH/n-PrOH) and a lower apparent concentration of ethanol. In a separate study, we showed that the concentration of ethanol was lowered even more when a 4-carbon alcohol (t-butanol) was used as the internal standard.     

On determining the relationship between blood alcohol concentration and smooth pursuit eye movements

Residual impairment after alcohol consumption implies that the relationship between blood alcohol concentration (BAC) and deficits in performance of some task is not the same when becoming intoxicated as it is when returning to sobriety. A pilot study was performed to determine the feasibility of and the appropriate methodology for studies on residual impairment of smooth pursuit performance. Four subjects consumed alcohol for 2 h. Measurements of BAC and smooth pursuit eye movements were made every 30 min during drinking and for 4 h after drinking. Pursuits were elicited by having subjects track a sinusoidal target (0.40 Hz and 0.60 Hz) for 10 s. Impairment of smooth pursuit was quantified with frequency analysis scores. Frequency analysis scores declined as BAC increased. As BAC decreased, frequency analysis scores tended to increase toward pre-drink levels. The relationship between BAC and frequency analysis score was not significantly different on the ascending and descending limbs of the blood alcohol curve. However, the idea that residual impairment does not occur could not be conclusively demonstrated for several reasons. First, as BAC returned to pre-drink levels, frequency analysis scores were inconsistent for each subject perhaps because of boredom and fatigue. Second, the relationship between BAC and frequency analysis score varied between subjects. Finally, because the recording periods were short, the effect of alcohol on sustained attention could not be assessed. In this paper, potential artifacts in studies of residual impairment of pursuits are discussed and potential solutions to the methodological problems encountered in the pilot study are provided.