Retrograde extrapolation of blood alcohol data: an applied approach

Serial Observation of Blood Alcohol Concentration post Ethanol Pleurodesis (SOBER) Study: A Prospective Observational Study

OBJECTIVES

To measure the blood alcohol concentration levels in patients after chemical pleurodesis with ethanol sclerosant via video-assisted thoracoscopic surgery.

DESIGN

Prospective observational study.

SETTING

Single tertiary university hospital.

PARTICIPANTS

Eight patients undergoing chemical pleurodesis with ethanol sclerosant for management of recurrent pneumothoraces or pleural effusions.

INTERVENTIONS

After ethics board approval, written informed consent was obtained from 8 patients undergoing chemical pleurodesis with ethanol sclerosant for management of recurrent pneumothoraces or pleural effusions. Five patients received a dose of 100 mL of 70% ethanol/1% iodine, and 3 patients received 30 mL. Blood alcohol concentration measurement was obtained at 30, 60, 90, and 120 minutes after the ethanol was instilled in the interpleural space. The postoperative quality of recovery scale was conducted preoperatively and then at 30 and 60 minutes postoperatively and on postoperative days 1 and 3.

MEASUREMENTS AND MAIN RESULTS

The highest observed blood alcohol concentration was recorded at 30 minutes post-instillation of ethanol in all patients. The blood alcohol concentration peak for 75% of patients (6/8) was >0.05 g/dL at 30 minutes post-instillation of ethanol, and for 4 patients (50%), this remained >0.05 g/dL at 60 minutes. The median area under curve of ethanol absorbed was 5.66 g/dL/min (3.24-7.29).

CONCLUSIONS

Significant systemic absorption of ethanol can occur after instillation of ethanol sclerosant, which potentially may affect the quality of recovery in patients. Postoperative management of these patients may need to be specifically tailored to take into account these observations.

Feed Safe: a multidisciplinary partnership approach results in a successful mobile application for breastfeeding mothers

Issue addressed: Mobile applications are increasingly being used in health promotion initiatives. Although there is evidence that developing these mobile health applications in multidisciplinary teams is good practice, there is a gap in the literature with respect to evaluation of the process of this partnership model and how best to disseminate the application into the community. The aim of this paper is twofold, to describe the partnership model in which the Feed Safe application was developed and to investigate what worked in terms of dissemination.Methods: The process of working in partnership was measured using the VicHealth partnership analysis tool for health promotion. The dissemination strategy and reach of the application was measured using both automated analytics data and estimates of community-initiated promotion.Results: The combined average score from the partnership analysis tool was 138 out of a possible 175. A multipronged dissemination strategy led to good uptake of the application among Australian women.Conclusions: Multidisciplinary partnership models are important in the development of health promotion mobile applications. Recognising and utilising the skills of each partner organisation can help expand the reach of mobile health applications into the Australian population and aid in good uptake of health promotion resources.So what?: Developing mobile applications in multidisciplinary partnerships is good practice and can lead to wide community uptake of the health promotion resource.

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.

Standardization of Alcohol Calculations in Research

BACKGROUND

Nonstandardized reporting of alcohol consumption, definitions of what constitutes a standard drink, and incomplete dosing or estimates of intoxication are common problems in many areas of alcohol research. To enhance communication among scientists and to make interpretation of results more accurate and meaningful, researchers need to apply systematically current scientific principles in calculating drinks, doses, and alcohol concentrations. Basic formulas are compiled and explained to assist alcohol researchers and standardize the reporting and interpretation of alcohol data.

METHODS

Basic alcohol calculations are reviewed, and 20 mathematical calculations in alcohol pharmacokinetics and pharmacology are derived. Examples of how each calculation works are presented.

RESULTS

The formulas presented enable researchers to calculate accurately and systematically the amount of alcohol in any beverage and estimate the blood alcohol concentration in a range of subjects with individual characteristics and drinking patterns.

CONCLUSIONS

Accurate estimates of alcohol use and intoxication are important in many areas of research. Applying standards to the way alcohol is measured and interpreted enables better communication, more accurate analyses, and, in some cases, may impact the interpretation of results. Regardless of the field of study, alcohol researchers are encouraged to and can apply uniform standards in measuring alcohol consumption and estimating the effects of alcohol using the scientific methodologies described.

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.

Self-assessment of inebriation from external indices

OBJECTIVE

The objective was to study people's judgments, through the use of external indices, of their expected degree of inebriation and to characterize the cognitive processes involved in making these judgments.

METHOD

The participants were 143 adults living in France. In accordance with N. H. Anderson's functional theory of cognition (1982, 1996), their primary task was to read 64 cards depicting drinking situations characterized by three parameters: number of glasses, type of drink, and temporal relation to eating; to associate with each situation a certain degree of personal intoxication; and to indicate this degree of expected intoxication on linear scale anchored by Not at all drunk and Extremely drunk.

RESULTS

Participants were able to judge the general direction and combination of effects. They indicated incorrectly, however, that incremental effects decrease at higher levels of consumption (4 or more glasses) and at higher concentrations of alcohol in a drink. On the other hand, they indicated correctly that eating food decreases the impact of drinking alcohol. Drinkers and nondrinkers used different rules for self-assessment from external indices. IMPICATIONS: The systematic errors in both drinkers' and nondrinkers' use of external clues could, unless corrected, result in their becoming more inebriated than intended.

Guidelines for estimating the amount of alcohol consumed from a single measurement of blood alcohol concentration: re-evaluation of Widmark's equation

This article deals with the pharmacokinetics of ethanol and the reliability of estimating the amount of alcohol ingested from a single measurement of a person's blood alcohol concentration (BAC). Blood alcohol curves were plotted for 108 male subjects after they drank various doses of ethanol (0.51-0.85 g/kg body weight). The rate of disappearance of ethanol from the blood (beta-slope) and the apparent volume of distribution of ethanol (Widmark's rho factor, rho) were calculated for each subject; the mean beta-slope was 13.3 mg/dl/h (SD = 2.0), and the mean rho factor was 0.689 l/kg (SD = 0.061). The value of beta increased slightly with increasing dose of alcohol (P < 0.05). The blood alcohol parameters beta and rho were negatively correlated (r = -0.135). The BACs measured at 2 h and 5 h post-drinking were used to estimate the amount of alcohol each subject had consumed according to the method proposed by Widmark [1]. The mean differences (estimated-actual) and the +/- 95% limits of agreement were -0.72 g (+/- 12), and 2.2 (+/- 15), for the 2 h and 5 h BAC values, respectively. A method based on error propagation was used to derive the 95% limits of uncertainty in the amount of alcohol ingested. On the basis of a single measurement of BAC, we could estimate the amount of alcohol ingested within +/- 20%.