The alcohol used for cleansing the venipuncture site does not jeopardize blood and plasma alcohol measurement with head-space gas chromatography and an enzymatic assay

Does cleaning of venipuncture site with alcohol affect blood ethanol concentration?

Background

It is important to accurately determine the blood ethanol concentration (BEC) to ensure appropriate diagnosis and treatment of patients in the emergency department (ED) and protect their legal rights. This study aimed to determine whether sterilization of venipuncture site with ethanol, which is frequently used in practice in the ED would affect BEC.

Methods

Venous blood samples were collected by two consecutive techniques from 94 individuals who were admitted to the ED, had an indication for BEC measurement, and volunteered to participate in the study. The reference technique involved applying 3 cc of 10 % povidone-iodine solution to a gauze pad, cleaning the right arm antecubital region, and performing phlebotomy. The index technique used 3 cc of alcohol-based antiseptic (89 % ethanol) on another gauze for cleaning the left arm antecubital region. Both techniques allowed the antiseptic to air-dry for 30 s before phlebotomy. Two blood sample tubes per patient were sent to the laboratory, and BEC were measured using the alcohol dehydrogenase enzymatic method.

Results

94 patients were included in the study. The mean age was 37.8 years (±15.7), with 77 % (n = 72) of them were male. The median BEC levels measured by both the reference and index techniques were 2 mg/dL (IQR: 0.97-16.25) and 2 mg/dL (IQR: 0.90-15.22), respectively, with no significant statistical difference (p = 0.536). 72 (77 %) of the patients had a BEC level below the legal driving limit of 20 mg/dL. Bland-Altman analysis, performed on these patients, revealed a small negative bias, -0.116 mg/dL with a standard deviation of 1.13 mg/dL. The upper and lower limit of the agreement was 2.092 and -2.323 respectively.

Conclusion

In patients with a BEC level of less than 20 mg/dL, using ethanol-containing antiseptics before blood sampling does not lead to erroneously elevated BEC levels.

Post-mortem formation of ethanol: Is 1-propanol a reliable marker? A proof-of-concept study using an in vitro putrefactive environment setup

Ethanol is the psychoactive substance identified most frequently in post-mortem specimens. Unfortunately, interpreting post-mortem ethanol concentrations can be difficult because of post-mortem alcohol redistribution and the possibility of post-mortem alcohol neogenesis. Indeed, in the time interval between death and sample collection, the decedent may be exposed to non-controlled environments for an extended period, promoting microbial colonization. Many authors report that in the presence of carbohydrates and other biomolecules, various species of bacteria, yeast, and fungi can synthesize ethanol and other volatile substances in vitro and in vivo. The aim of this study was to study the impact of several variables on microbial ethanol production as well as develop a mathematical model that could estimate the microbial-produced ethanol in correlation with the most significant consensual produced higher alcohol, 1-propanol. An experimental setup was developed using human blood samples and cadaveric fragments incubated under strictly anaerobic conditions to produce a novel substrate, "cadaveric putrefactive blood" mimicking post-mortem corpse conditions. The samples were analyzed daily for ethanol and 1-propanol using an HS-GC-FID validated method. The formation of ethanol was evaluated considering different parameters such as putrefactive stage, blood glucose concentration, storage temperature, and storage time. Statistical analysis was performed using the Mann-Whitney non-parametric test and simple linear regression. The results indicate that the early putrefactive stage, high blood glucose concentration, high temperature, and time of incubation increase microbial ethanol production. In addition, the developed mathematical equation confirms the feasibility of using 1-propanol as a marker of post-mortem ethanol production.

To disinfect or not to disinfect that is the question - Procedure when drawing blood for alcohol measurements in Denmark

Swabbing with ethanol to disinfect the skin before venipuncture does not bias measurements of blood ethanol, as previously suspected. International evidence-based theory may not always be successfully integrated into local practices, where old customs may remain. So how are the local protocols for swabbing in practice - if they even do swab? Not disinfecting may risk patient safety. We aim to put a focus on the venipuncture disinfection procedure in practice when measuring blood alcohol for clinical matters and if their procedure refers to a guideline. Specialized biomedical laboratory scientists (BLS) are typically responsible for the phlebotomy procedure in Denmark, thus questionnaires were sent to the relevant BLS in 2020 to map disinfection procedures in all Danish hospitals and affiliated blood draw clinics (n = 58). The response rate was 93% (54/58). We observed an inter-laboratory dissimilarity in swabbing procedures, when measuring blood alcohol: A quarter did not use any disinfectant (26%), while the remaining disinfected with ethanol 55%, isopropanol 13%, and 6% with ethanol/chlorhexidine. Of the five Danish regions, three had a regional guideline (3/5), otherwise the swabbing protocol was locally based. There was a regional difference in disinfecting or not (Chi2 p < 0,0001). Danish protocols do not always parallel international literature and international guidelines. Not applying disinfectant may jeopardize patient safety. Laboratories are encouraged to work with evidence-based practice or follow newest standardized international guidelines.

Blood alcohol concentration in the clinical laboratory: a narrative review of the preanalytical phase in diagnostic and forensic testing

The analysis of blood alcohol concentration (BAC), a pivotal toxicological test, concerns acute alcohol intoxication (AAI) and driving under the influence (DUI). As such, BAC presents an organizational challenge for clinical laboratories, with unique complexities due to the need for forensic defensibility as part of the diagnostic process. Unfortunately, a significant number of scientific investigations dealing with the subject present discrepancies that make it difficult to identify optimal practices in sample collection, transportation, handling, and preparation. This review provides a systematic analysis of the preanalytical phase of BAC that aims to identify and explain the chemical, physiological, and pharmacological mechanisms underlying controllable operational factors. Nevertheless, it seeks evidence for the necessity to separate preanalytical processes for diagnostic and forensic BAC testing. In this regard, the main finding of this review is that no literature evidence supports the necessity to differentiate preanalytical procedures for AAI and DUI, except for the traceability throughout the chain of custody. In fact, adhering to correct preanalytical procedures provided by official bodies such as European federation of clinical chemistry and laboratory medicine for routine phlebotomy ensures both diagnostic accuracy and forensic defensibility of BAC. This is shown to depend on the capability of modern pre-evacuated sterile collection tubes to control major factors influencing BAC, namely non-enzymatic oxidation and microbial contamination. While certain restrictions become obsolete with such devices, as the use of sodium fluoride (NaF) for specific preservation of forensic BAC, this review reinforces the recommendation to use non-alcoholic disinfectants as a means to achieve "error-proof" procedures in challenging operational environments like the emergency department.

Validation of a New Salt-Assisted HS-GC-FID Method for the Determination of Ethanol in the Vitreous Humor

Headspace gas chromatography with a flame ionization detector (HS-GC-FID) is a well-established approach for determining blood alcohol concentration, including in cadaveric specimens. Although the integrity of blood specimens can be adequately guaranteed after the sampling, the quantification of ethanol in cadaveric blood can be affected by postmortem fermentative phenomena occurring between the time since death and the sampling of biofluids. The vitreous humor is less affected by putrefactive phenomena allowing compound determination and its use as an alternative biological matrix. The present work aimed to develop and validate a method using the salting-out effect and based on HS-GC-FID for the determination of ethanol in the vitreous humor. The reported analytical method is based on a simple vitreous humor pre-treatment consisting of a dilution (1:9) with a solution of 2.5 mol/L K2CO3 and 0.0012 mol/L tert-butanol (internal standard). After 1 min of incubation, part of the specimen evaporated in the headspace (2,000 µL) is injected into the chromatographic system and analyzed in isothermal mode (40°C), with a chromatographic time of 1.6 min. The method was validated in terms of selectivity, the lowest limit of detection, intraday and total imprecision, and trueness (bias). The determination of ethanol in the vitreous humor and blood was carried out in 75 cases. The correlation between the two matrices was confirmed in 61 cases. However, 14 vitreous humor specimens showed lower ethanol concentrations, and in the related blood specimens, it was possible to identify the signal of n-propanol, a typical product of postmortem microbial fermentation, that justifies the excess of ethanol in the blood specimens.

Isobutylene contamination of blood collected in 10-ml evacuated blood collection tubes with gray conventional rubber stoppers

Dual-column headspace gas chromatographic analysis with two flame-ionization detectors is a commonly used analytical technique for forensic blood ethanol quantitation. This technique is also applicable to the identification and quantitation of other volatile organic compounds such as methanol in biological samples. Compound identification by retention time is limited to those compounds with known retention times programmed into the instrument method. Historically, an early-eluting peak from an unidentified compound has been observed in both chromatograms from antemortem blood samples analyzed for ethanol concentration with this technique. The unidentified compound's retention time matches that of methanol on one column but not on the second column. This previously unidentified compound has been identified as isobutylene. The proposed source of the isobutylene contamination historically observed in antemortem blood samples collected in 10-ml gray-top blood collection tubes is the conventional rubber stopper. Isobutylene was detected in deionized water stored in each of the seven lots of 10-ml blood tubes tested; the expiration dates of the tubes tested spanned the years 2002-2022. Misidentification of isobutylene as methanol is possible when using a single-column gas chromatographic system. The presence of isobutylene in blood collected in a gray-top collection tube does not represent laboratory contamination, is not an interferent with blood ethanol quantitation, and does not affect the ethanol concentration in the blood. A 0.150 g/dl aqueous ethanol standard was stored in a gray-top tube to evaluate the potential impact of isobutylene on ethanol quantitation. The solution's average ethanol concentration measured after storage was 0.150 g/dl.

Alcohol-associated traffic injuries in Verona territory: A nine-year survey

According to the World Health Organization, as many as 25% of traffic accidents are linked to alcohol abuse. This study describes the results of a nine-year study performed on injured drivers (N = 12,806) in the Verona area of Northern Italy. Blood samples were mandatorily collected on injured drivers who were admitted to the Emergency Health Care Unit of Verona Hospital between 2009 and 2017, after they had been involved in a traffic accident. Blood alcohol concentration (BAC) determination was then undertaken using a validated head space-gas chromatography-flame ionisation detector (HS-GC-FID) method. We found that 21% of drivers tested positive for alcohol (BAC ≥0.01 g/L), while 16.8% presented with BAC levels above the Italian legal limit (>0.5 g/L). Of those who had positive BACs, about 50% presented with very high BAC levels (>1.5 g/L). Daily time distribution analyses, involving 2031 alcohol-positive drivers, showed a surge between 18:00 hours and 06:00 hours (74.3%), with a specific rise during the weekend (58.9%). The percentage of alcohol-related road accidents was 20.6%, which is lower than results reported in other international studies performed over the last 20 years. However, evidence that around 50% of the positive subjects showed a BAC >1.5 g/L confirms the correlation between BAC and accident risk, which becomes even more significant at progressively increasing levels of BAC. The study highlights the need to implement further strategies to both prevent and deter the use of alcohol while driving.

Quantification of Ethanol Levels in Zebrafish Embryos Using Head Space Gas Chromatography

Fetal Alcohol Spectrum Disorders (FASD) describe a highly variable continuum of ethanol-induced developmental defects, including facial dysmorphologies and neurological impairments. With a complex pathology, FASD affects approximately 1 in 100 children born in the United States each year. Due to the highly variable nature of FASD, animal models have proven critical in our current mechanistic understanding of ethanol-induced development defects. An increasing number of laboratories has focused on using zebrafish to examine ethanol-induced developmental defects. Zebrafish produce large numbers of externally fertilized, genetically tractable, translucent embryos. This allows researchers to precisely control timing and dosage of ethanol exposure in multiple genetic contexts and quantify the impact of embryonic ethanol exposure through live imaging techniques. This, combined with the high degree of conservation of both genetics and development with humans, has proven zebrafish to be a powerful model in which to study the mechanistic basis of ethanol teratogenicity. However, ethanol exposure regimens have varied between different zebrafish studies, which has confounded the interpretation of zebrafish data across these studies. Here is a protocol to quantify ethanol concentrations in zebrafish embryos using head space gas chromatography.