The estimation of blood alcohol concentration

Expert witnesses and others involved in toxicology are frequently asked to perform retrograde extrapolation of blood alcohol concentration (BAC) or to estimate BAC based on a proposed drinking scenario. Although many individuals are reluctant to perform these calculations and some jurisdictions expressly prohibit them, a significant number of practitioners routinely estimate BAC based on this type of calculation, using as a basis the fundamental work of Widmark. Although improvements to the Widmark formula and other data pertaining to the pharmacology of alcohol have been published, these improvements are frequently ignored when estimating BAC. This article summarizes five published models for the estimation of BAC and proposes a sixth model that incorporates recent data on the rate of absorption of alcohol from the GI tract into the existing five models. The five improved models can be computerized and used to construct comparative snapshots of the BACs calculated by the different algorithms. This will allow practitioners to provide a more balanced picture of the variability in BAC calculations.     

Pharmacokinetic analyses using absorption kinetics in low-alcohol dose cases of drunken driving

In Japan, low-alcohol dose cases of drunken driving, where drivers drink just before getting behind the wheel, are increasing for expert witnesses since the penalties for drunken driving have become stricter. Widmark’s equation has generally been used for the pharmacokinetic analysis of blood alcohol concentration, which encompasses the one-compartment model with zero-order elimination kinetics but ignores absorption kinetics. We therefore propose that the formula might not be applicable to the analysis of low-alcohol dose cases of drunken driving because the issue is focused on the absorption phase. In this paper, we present two representative low-alcohol dose cases, which were analyzed using the one-compartment model with first-order absorption and zero-order elimination kinetics. This formula is thought to be more suitable and useful for medicolegal practice than Widmark’s formula.     

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.     

Treffsicherheit der Berechnung der Tatzeitblutalkoholkonzentration in Nachtrunkkonstellationen

Background

The calculation of a detectable minimum or maximum blood alcohol concentration (BAC) in the legal sense follows rules based on the basic principle of in dubio pro reo. In traffic law the question of the minimum detectable BAC is often asked in a situation concerning an irrefutable hip flask defence. In this situation the legal principle of in dubio pro reo currently requires the extreme upper and lower values to be included in the calculation, even if this is very problematic from a pharmacokinetic aspect.

Aim

The study aimed to estimate the accuracy of BAC calculations in hip flask defence constellations.

Material and methods

Drinking experiments were carried out with 55 volunteer subjects to simulate a hip flask defence constellation. In group 1 (n?=?32) a large amount of alcohol was drunk before the theoretical offence followed by a small amount of alcohol after the event and in group 2 (n?=?23) a small amount of alcohol was drunk before the theoretical offence followed by a large amount of alcohol after the event. In group 1 there was a time lapse of approximately 60 min between drinking before and after the theoretical event and of 30 min between the two alcohol intake times in group 2. Within this lapse of time, a particular time for the alleged offence was defined shortly before the start of the second alcohol intake. A back calculation to the theoretical time of the offence was performed starting from two fictive points in time of blood sampling of 120 min after the last alcohol intake before the offence occurred. The results of the back calculation were compared with the values measured at the theoretical time of the event.

Results

In most cases the estimated results of the back calculation were approximately 0.05 g alcohol/kg body weight lower than the measured values; however, in three male subjects the back calculation was higher than the analysis values.

Conclusion

The well-established equations for back calculation of the BAC at the time of the event lead to false estimations where resorption is greatly prolonged or where diffusion is drastically affected. However, overestimation can be justified due to a strong resorptive phase and in cases of extreme underestimation this at least does not lead to a disadvantage for the affected individual. The comparatively few miscalculations do not fundamentally cast doubt on the basic principles for estimating the amount of alcohol consumed after an offence. It could be shown that this concerns cases where the amount of alcohol present in the subject’s body, formulated according to current legislation, would have led to a clearly higher blood alcohol concentration irrespective of the alcohol consumed after the offence.     

Computer simulation analysis of blood alcohol

A mathematical model using an iterative algorithm based on the Widmark formula is used to simulate a continuous spectrum of the expected blood alcohol concentration from start of alcohol dosage to time of specific event in numerical and graphic form. Absorption is based on flexible first order rates with provision for an optional good-fit model of the delaying effect of food. Elimination is based initially on selectable zero order rates followed by first order kinetics at low blood alcohol concentrations. A correlation coefficient of 0.94 was obtained in comparisons of projected to observed blood alcohol concentrations. A measurement of the area under the curve is provided. The software program utilizing the algorithm is suitable for forensic and clinical applications.     

Pilots' knowledge of blood alcohol levels and the 0.04% blood alcohol concentration rule

A national sample of licensed pilots was surveyed regarding their knowledge of the Federal Aviation Administration's (FAA) 0.04% blood alcohol concentration (BAC) limit, the relationship between the number of drinks and BAC, and the manner in which BAC decays with time. A majority of the 1039 respondents were unaware of the 1985 0.04% BAC rule change. In addition, many lacked an understanding of the relationship between the amount of alcohol consumed and the resulting BAC, and of the rate at which BAC decays. The number of drinks necessary to raise BAC to specific levels was frequently overestimated, and the amount of time necessary for BAC to decay was frequently underestimated. These errors were more pronounced for moderate and heavy drinkers than for abstainers and infrequent drinkers. These results suggest that pilots could have difficulty if they attempt to use the 0.04% BAC value as a guide to safety in their flying activities.     

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.     

Effects of alcohol on body-sway patterns in human subjects

The vestibulospinal aspects of vestibular function are commonly neglected in the evaluation of alcohol-induced intoxication. Thus, in the present study the effect of an acute intoxication with a low or moderate quantity of alcohol was examined with respect to the equilibrium in 30 healthy subjects. The blood alcohol concentration (BAC) was measured 30 min after the ingestion of the last alcohol, ranging between 0.22 and l.59‰. Stability of stance was quantified by static platform posturography in Romberg-test conditions with eyes open and eyes closed. Among other parameters, the average body sway path (SP) and area of body sway (SA) were assessed. Posturography revealed a significant increase in body sway. There was a positive correlation between SA (or SP) and BAC both with eyes open and eyes closed. Multiple group comparisons revealed that the large-alcohol-dose group (BAC ≥ 1.0‰) could be clearly differentiated from test cases with BAC lower than 0.8‰. Sway area was the most sensitive parameter for detecting increased body sway after alcohol ingestion. The area increase, present not only with eyes closed but with eyes open, revealed an inadequate compensation of the ethanol-induced ataxia by visual stabilization. The Romberg’s quotient, which denotes eyes closed relative to eyes open, remained constant. The increase in sway path with eyes closed showed an omnidirectional sway. A comparison of the sway pattern of subjects after acute ethanol ingestion with the data of patients with permanent cerebellar lesions suggested that the acute effect of alcohol resembles that of a lesion of the spinocerebellum. This finding contrasts with earlier studies, which postulated an acute effect of ethanol resembling that in patients with an atrophy of the anterior lobe of the cerebellum due to chronic alcohol abuse. In seven cases of the lower dose group (BAC ≤ 0.8‰), a reduction in body sway after alcohol ingestion was observed. This finding may be consistent with a dose-related biphasic action of alcohol, which – besides its well-known depressant effects with high doses – also shows stimulatory action with small doses. Received: 5 January 1998 / Received in revised form: 3 July 1998     

Reliability of clinical decisions regarding alcohol influence

In Jordan, pursuing legal procedures related to alcohol intake usually depends on the physicians' clinical judgment. A study was carried out on 825 medico-legal cases over a 2 year period to evaluate the extent of physicians' clinical decisions on patients suspected to be under the influence of alcohol. A significant number of cases (12.6%, n = 104) were found to be positive for alcohol. The study showed that the clinical examination failed to diagnose a large number of cases (78.9%, n = 82). Also, the majority of diagnosed cases (50%, n = 11) had a blood alcohol concentration (BAC) range of 50-100 mg/dl. 32% (n = 33) of the cases with positive BAC were admitted to hospital. A high admission rate was observed when BAC was <50 mg/dl and >150 mg/dl, which constituted 39.3% (n = 13) and 48.5% (n = 16) of the admitted cases respectively. A large number of the admitted cases had either simple or no trauma (48.4%, n = 16) as compared with the control group of cases (21.8%, n = 10). The admission rate of positive BAC cases in traffic accidents was double that of control group. These findings may reflect the unreliability of the clinical decision in positive BAC. Implementing a certain BAC level locally for both clinical and a jurisdiction purposes is strongly recommended.     

不同饮酒量对中老年人体质、血脂及高血压、冠心病发生率的影响

本文根据276例男性中老年人饮酒情况,分别测定体质指数、体重指数及血脂,并观察高血压病、冠心病、高胆固醇血症及高甘油三酯血症的发生率。结果表明,轻度饮酒组的高密度脂蛋白胆固醇(HDL—C)的浓度与对照组相比明显升高(P<0.01),冠心病、高胆固醇血症的发生率较低(P<0.05);重度饮酒组体重指数、总胆固醇(TC)含量及高血压病发生率最高,与对照组相比有显著差异(P<0.01或P<0.05)。体质指数、甘油三酯(TG),低密度脂蛋白胆固醇(LDL—C)水平三组相比则无明显差异(P>0.05)。此结果揭示:重度饮酒对人体是有害的,轻度饮酒虽可升高HDL—C,有利于预防冠心病的发生,但其产生的保护性效果,易被其他方面产生的危险性抵消,所以我们主张中老年人应尽量不饮酒或少饮酒。     

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.     

The use of an alcometer in clinical forensic practice

Forensic physicians are at times required to provide a professional opinion on a person's degree of intoxication through alcohol, particularly with regard to fitness for interview by the police. Inherent to these assessments is an estimation of the blood alcohol concentration (BAC). Most forensic physicians rely on taking a history regarding recent alcohol consumption and a clinical assessment to estimate the BAC. We report a study in which the BAC of 118 detainees was estimated and compared with the BAC measured by an alcometer. Our estimations were accurate in 66% of cases. Most errors resulted from underestimating the BAC. Additionally, we attempted to determine fitness for interview using a single measurement of the BAC without a clinical assessment. 19% of those who were assessed as unfit for interview had a BAC of less than the UK legal limit for driving (currently 80 mg%) and 37% considered fit, had a BAC above that level. We conclude that the routine use of alcometers would enhance the practice of forensic medicine but could not replace its role in the assessment of levels of alcohol intoxication.     

体表面积烧伤复苏公式补液探讨

目的 探讨大面积烧伤休克期液体复苏的方法。方法 156例以体重指数(BMI)分为三组,1组BMI<24、2组BMI24-27和3组BMI>27。全部病例假以60%TBSA,分别用中国复苏公式和体表面积复苏公式计算补液量,进行对比分析。结果 体表面积补液公式估算量为6620.79ml,稍多于中国烧伤复苏公式估算量6287.02ml(p<0.01)。进一步分析,体重指数24-27,两公式计算量无差异;BMI<24中国烧伤液体复苏公式估算量偏少;BMI>27估算量偏多。结论 传统公式估算补液量受体重影响,新公式去除体重参数避免了对估算量的影响,并引入体表面积参数矫正烧伤面积,扩大了公式的适用范围,可用于各类人群烧伤补液量的估算。     

Time since death nomographs implementing the nomogram,body weight adjusted correction factors,metric and imperial measurements

The concept of nomography was developed around 1880 as a means to compute formulas graphically. Regular use has decreased over time in most fields, mainly owing to progress in electronic computation devices. In forensic pathology, nomography is still used in the so-called “nomogram method” for the estimation of time since death. It is the graphical representation of the formula by Marshall and Hoare with the parameters of Henssge. Here, two nomograms exist (for ambient temperatures below and above 23 °C, no imperial measurements). Rounding for body weight input and result reading introduces errors. In addition, correction factors, applied to body weight, allow to adapt for certain conditions on the crime scene and are essential to the method. They are not directly integrated into the nomograms but must be applied in advance. A formula, scaling correction factors for different body weights, was later added by Henssge, along with a simplified table for case work. In this publication, we present newly designed time since death nomographs as representations of Henssge’s parameters with the addition of both metric and imperial measurements, integration of weight adjusted scaling of correction factors, and a geometrically consistent framework for body weight and result reading, which eliminates some rounding steps and reduces the overall rounding-related estimation errors.

     

补充八子补肾胶囊对男子足球运动员赛前准备期和比赛期血液生化指标和运动能力的影响

目的:观察补充八子补肾胶囊对男子足球运动员赛前准备期和比赛期血液生化指标和运动能力的影响。方法:选择16名足球专项男子运动员进行单盲、交叉实验。其中服药期各4周,清洗期2周。每周训练4天,每天进行一堂90 min训练课;每周比赛一场。服药组每天服用八子补肾胶囊的剂量为4粒/次,0.4 g/粒,2次/日;对照组服用外观相同的等量对照胶囊(安慰剂)。服药前后均进行运动能力、体成分和血液生化测试。结果:服用八子补肾胶囊受试者实验后体重、血清睾酮(T)水平和耐力运动成绩未见明显变化;体脂重量和体脂率较实验前明显降低,无氧功率显著提高(P<0.05)。服用对照胶囊受试者实验后体重、血清T水平和耐力运动成绩明显下降(P<0.05),但体脂重量、体脂率和无氧功率未见明显改变。结论:服用八子补肾胶囊能在运动员赛前准备期和比赛期间保持体重、减少体脂重量和体脂率,维持运动耐力并提高无氧运动能力,维持运动员血清睾酮水平稳定。     

Intra-individual and inter-individual variation in breath alcohol pharmacokinetics: The effect of short-term variation

Ten male and 8 female students underwent serial breath alcohol concentration (BrAC) measurements on a CAMIC Datamaster on two consecutive occasions, early evening and again the following morning. Subjects were fasted for 6 h before receiving alcohol as white wine (12.5% by volume) at doses of 38–45 g for males and 26–37 g for females, consumed over 10 min. Specific individual doses were calculated individually from height and weight (according to the Forrest Method) to give target C₀ breath alcohol concentrations of 35 μg/100 ml breath in males and 31 μg/100 ml breath in females.BrAC versus time curves were constructed for each subject and the values of peak BrAC (C_max), BrAC extrapolated at zero time (C₀), time taken to reach peak (T_max) and rate of elimination (ß) were recorded directly from the curves. Values of C₀ taken from the BrAC–time curves varied widely, from 21 to 47 μg/100 ml on visit 1 and from 22 to 45 μg/100 ml on visit 2. Widmark Factors calculated from these C₀ values averaged 0.74 (range, 0.59–1.06) in males and 0.73 (range, 0.58–1.05) in females. Elimination rate was higher in the morning than evening in both males (7.4 versus 5.7 μg/100 ml/h) and females (6.9 versus 5.8 μg/100 ml/h). Elimination rates in males and females were not significantly different. Total body water, measured by electronic scales, averaged 58.7% (range, 56.6–63%) in males and 48.3% (range, 40.9–57.6%) in females. Widmark Factors calculated by various established mathematical methods were 0.73–0.77 in males and 0.61–0.64 in females.     

The blood alcohol concentration at post-mortem in 175 fatal cases of alcohol intoxication

The mean blood alcohol concentration (BAC) in 175 fatal cases of acute alcohol intoxication was found to be 355 mg/100 ml. This figure is less than that quoted in many standard textbooks on forensic medicine. The BAC in fatal cases of acute alcohol intoxication complicated by aspiration was lower than in those cases where there was no evidence of aspiration at autopsy. In those individuals with a previous history of alcohol abuse the BAC causing death was found to be significantly higher than in those without a history of prolonged heavy alcohol consumption suggesting that a degree of tolerance to the effects of alcohol may be induced.     

The influence of alcohol and aging on radio communication during flight

This study finds that alcohol and pilot age impair radio communication during simulated flight. Young (mean age 25 years) and older (mean age 42 years) pilots flew in a light aircraft simulator during alcohol and placebo conditions. In the alcohol condition, pilots drank alcohol and flew after reaching 0.04% BAC, after reaching 0.10% BAC, and then 2, 4, 8, 24, and 48 h after they stopped drinking at 0.10% BAC. They flew at the same times in the placebo condition. Alcohol and age impaired communication-based and overall flying performance during and immediately after drinking. Most important, alcohol and age cumulatively impaired performance, since older pilots were more impaired by alcohol. Notably, performance was as impaired 2 h after reaching 0.10% BAC as it was at 0.10% BAC. Moreover, overall performance was impaired for 8 h after reaching 0.10% BAC.     

Slowing effects of alcohol on voluntary eye movements

The effect of a moderate dosage of alcohol on the latency and saccadic velocity of eye movements was assessed by three kinds of task complexities such as the "simple," "comparison," and "addition response tasks" to displayed stimuli. Six male subjects volunteered for the study. For each subject, a total of 570 trials were made on four consecutive days. In terms of absolute alcohol, the dose was 1.0 ml.kg-1 of body weight. The slowing effect of alcohol on the latency ranged from 8.4 to 16.8% (mean 12.7%) corresponding to the task complexity. The impairment of the saccadic velocity ranged from 17.4 to 25.5% (mean 18.6%). It was suggested that the task complexity reflected on the latency, but not on the saccadic velocity.     

BAK-AAK-Quotient im Konzentrationsbereich von 0,5‰ (0,25 mg/l Ausatemluft) Eine Trinkversuchserie mit dem geeichten Atemalkoholtestgerät Alcotest 7110 MK III A (Österreich-Ausführung)

In this study the analytical performance of the breath alcohol analyser Alcotest MK III A from Dräger was evaluated in the concentration range of 0.25 mg/l to collect data for the determination of the blood alcohol-breath alcohol (BAC-BrAC) quotient. This breath testing device has been approved for use in Austria since 1997 and differs in some technical aspects from the Alcotest 7110 MK III Evidential, which is approved for use in Germany. In 32 controlled experiments the BAC and BrAC of 139 participants were determined simultaneously 30 min after the last consumption of alcohol. The measured BAC and BrAC values ranged between 0.14 and 1.72‰ (g/l), and 0.05 and 0.78 mg/l, respectively. A conversion factor (CF) between BAC and BrAC was determined from these data pairs with a minimum of 1,380 and a maximum 2,720 and a mean value of 2,062. Due to the large variability of the CF, analysis of BAC is preferable to using conversion calculations from a forensic point of view. According to our data, if only BrAC values are available a CF ranging from 1,631 (min) and 2,493 (max) can be used to convert BrAC to BAC with a statisticl significance of 95%.