Mean BAC Research Articles

Waiting for the Patient to ???Sober Up???: Effect of Alcohol Intoxication on Glasgow Coma Scale Score of Brain Injured Patients

Between 35% to 50% of traumatic brain injury (TBI) patients are under the influence of alcohol. Alcohol intoxication may limit the ability of the Glasgow Coma Scale (GCS) to accurately assess severity of TBI. We hypothesized that alcohol intoxication significantly depresses GCS scores of TBI patients. A 10-year, retrospective analysis of a Level I trauma center registry was undertaken. The study population consisted of all blunt injured TBI patients tested for blood alcohol concentration (BAC, n = 1,075). Patients were divided into two groups; intoxicated (mean BAC 202 +/- 77 mg/dL, n = 504) and nonintoxicated (BAC = 0, n = 571). TBI was classified using ICD-9 codes as concussion alone (ICD-9 850, n = 90) and intracranial injury (ICI, ICD-9 851-854, n = 985). Severity was further classified using the Abbreviated Injury Score (AIS). Mean GCS score was compared between the two groups. Patients who were either intubated or hypotensive upon arrival were analyzed separately to rule out confounding effects on GCS score. Severely intoxicated patients (BAC >250 mg/dL, [mean +/- SD] 309 +/- 54 SD, n = 118) were similarly compared. Finally, multivariate linear regression analysis was undertaken to determine whether BAC level was an independent predictor of GCS score while controlling for confounding factors. Intoxicated and nonintoxicated TBI patients were clinically similar. Alcohol intoxication had little effect on GCS score, with less than a single point difference in all types of TBI, except the most severely injured (AIS 5 injuries, GCS score difference 1.4 points). These results were not altered by endotracheal intubation, systemic hypotension, or severe intoxication. Similarly, BAC was not a significant independent predictor of GCS score in a multivariate model. Alcohol intoxication does not result in clinically significant changes in GCS score for patients with blunt TBI. Hence, alterations in GCS score after TBI should not be attributed to alcohol intoxication, as doing so might result in inappropriate delays in monitoring and therapeutic interventions.

Effects of alcohol on perceptual speed.

In moderate to heavy doses, alcohol adversely affects performance on many tasks, and perceptual speed is a component in most performance tasks. Nevertheless, studies of alcohol's effects on perceptual speed have been largely limited to critical flicker frequency and backward masking. The present study extends these limits. 16 men and 12 women were administered four temporal-factors tests before and after the ingestion of alcohol. The four tests were Simultaneity, Apparent Movement, Bistable Stroboscopic Motion, and Backward Masking. At the first postalcohol testing (mean BAC = 0.111), all four tests showed pre-posttest changes indicating slowed perceptual speed. Perceptual speed was still slowed when BAC decreased to .096. When mean BAC decreased to .076, however, only Simultaneity and Backward Masking were still significantly slowed. At moderate BACs and possibly at lower ones, the effects of alcohol on task performance appear to be mediated in part by slowed perceptual speed.

Individual differences in alcohol responsivity: physiological, psychomotor and subjective response domains.

Psychometrically stable measures of individual differences in response to consuming alcohol were developed as part of an ongoing project investigating "high-tolerant" drinking drivers. The derived measures were correlated with diagnostic criteria of alcohol abuse and dependence, as well as drinking frequency, heavy drinking and tolerance estimations. Male subjects (N = 94), 21 to 59 years old, participated in each of two identical alcohol consumption sessions (mean dose = 0.78 g/kg). Multiple response measures obtained before and after drinking (mean BAC = 78 mg/dl, descending) were used to compute postconsumption regression residuals that were factor analyzed. Factors reflecting psychomotor, subjective and physiological responsivity to alcohol were extracted. Confirmatory factor analyses indicated consistent psychomotor and physiological factor structures across the two testing sessions, but a bifurcation of the subjective measures. Test-retest correlations of the responsivity residuals indicated medium to moderately large effect sizes (mean = .32, range = .15-.51). Residuals summated within each response domain indicate moderate internal consistency (mean = .56, range = .45-.72) and higher reliabilities than single measure indices (range = .53-.59). Summated residuals within the response domains suggest diminished responsivity is associated with more severe alcohol-use diagnoses and were differentially predictive of self-reported drinking practices. Alcohol responsivity is multidimensional. Individual differences across different domains can be measured reliably and are associated with different patterns of alcohol use and abuse. Greater attention should be given to the specific domain of alcohol responsivity measures obtained in past and future research that relates individual differences to alcohol-related problems.

Drinking drivers in Sweden who consume denatured alcohol preparations: an analytical-toxicological study.

In the course of analyzing blood samples from drunk drivers, several low molecular weight volatiles were occasionally identified in addition to ethanol on the gas chromatograms. Among 21, 153 blood specimens analyzed during 1986, 77 contained ethanol as well as other volatile agents at the following mean concentrations: ethanol 2090 mg/L (range 830-3410), methanol 49.6 mg/L (range 20-178), acetone 88.3 mg/L (range 12-307), 2-propanol 32.2 mg/L (range 4-99), 2-butanone 49.2 mg/L (range 5-144), and 2-butanol 23.2 mg/L (range 4-64). A technical alcohol widely available in Sweden, trade name T-red, contains 92% w/w ethanol, 2% w/w acetone, and 5% w/w 2-butanone. A red coloring agent and a substance to impart a bitter taste (bitrex) are added to deter consumption. The drinking drivers who consumed technical alcohol were on average older (43 years compared with 35 years) and had higher mean BAC (2090 mg/L compared with 1767 mg/L). Those who drank denatured alcohol were more often apprehended while driving small motorcycles (mopeds) than were control groups of DWI offenders. The use of technical alcohol for intoxication might reflect, at least in part, the high costs and restricted availability of conventional alcoholic beverages in Sweden.

Analysis of body sway pattern after alcohol ingestion in human subjects.

Movements of the centre of gravity during 60 s of standing with eyes closed and eyes open were analysed before and after alcohol ingestion up to 8 h in 37 healthy human subjects. Blood alcohol and acetaldehyde concentrations (BAC and BAcHC) were measured simultaneously. Among the parameters analysed, area of posturogram was the most sensitive indicator; it increased to 3.8 times that of the control value at 60 min, after 3.5 ml/kg of ingested whisky (mean BAC of this group was 1.4 mg/ml), with the eyes open. The Romberg ratio, which denotes eyes closed relative to eyes open, remained constant. By contrast, there was little change in stabilometry in cases of 1.2 ml/kg of whisky ingestion (mean BAC at 60 min was 0.58 mg/ml). It is considered that body sway starts to increase when the BAC level exceeds 0.6 mg/ml on average; this value is only higher than the threshold of positional alcohol nystagmus. Correlation coefficients between BAC and each parameter of the stabilogram in the eyes open condition, such as area, X- and Y-axis diameters, and velocity of body sway, were 0.53, 0.45 and 0.48, respectively (p less than 0.01). There was no positive correlation between BAcHC and these parameters.

Event-related brain potentials in intoxicated and detoxified alcoholics during visuospatial learning

Event-related potentials and visuospatial learning performance were examined to understand the effects of chronic alcohol use on complex information processing. A total of 18 alcoholic male in-patients in an alcohol treatment program served as participants. Nine persons were seen at time of admission to the program while intoxicated (mean BAC = 18.0 mg/dl). The second group of nine persons was seen detoxified after 4 weeks in the treatment program. Learning consisted of a paired-associate paradigm requiring participants to learn the distinct spatial positions of six, randomly presented "nonsense" shapes. The visuospatial learning performance of the intoxicated alcoholics was superior to that of the detoxified alcoholics. Evaluation of event-related potentials during the visuospatial learning task indicated that while both groups displayed greater right hemisphere amplitudes of P3, P2, N1, and N2-P3 components, the amplitudes of the latter three components were significantly greater in the intoxicated alcoholics. The overall results suggest that compared to the intoxicated alcoholic, the detoxified alcoholic may suffer a disruption in attentional mechanisms related to visuospatial information processing, providing support for a theory that alcohol ingestion serves to balance information processing in the chronic alcoholic.

Alcohol and eye contact.

The effects of alcohol (0.9 g ethanol/kg body weight) on mood and eye contact were studied in male and female subjects engaged in dyadic interaction with unfamiliar, continuously gazing like‐sex or opposite‐sex interviewers. Thirty‐two volunteer students served as unpaid subjects in a 2 × 2 × 2 factorial design with four subjects per cell. Significant subjective increases in affiliative mood were observed in male as well as in female subjects at a mean BAC of 1.08 ± 0.12 g/l. Significant interactive effects were observed as functions of the sex of the subject and interviewer with alcohol/placebo treatment in analyses of pretreatment/post treatment change for two measures of gaze duration. The results were discussed in terms of the Argyle‐Dean conflict model and it was concluded that alcohol did not induce the net approach gain expected as a result of increased affiliation and/or reduced interpersonal avoidance. Sober subjects tended to look at their like‐sex interviewers more and drunk subjects less, the trend being particularly evident in female subjects. It was suggested that the effects of alcohol on eye contact may be strongly associated with sex‐roles.