Alcohol blood concentrations

Alcohol. The number of driving under the influence of alcohol (DUl) cases reflects the enormity of the dmnken driving problem in the United States (9). Tests to measure blood alcohol concentration are conducted on blood, urine, or breath (10). In the case of urine and breath, the alcohol concentration measured is reported in terms of the equivalent blood alcohol concentration. Most states in the United States presume that a person is under the influence of alcohol with respect to driving a motor vehicle at a blood alcohol concentration of 0.10%, ie, an ethanol concentration >10 g/100 mL of blood. Some states maintain a lower necessary concentration of 0.08%. In some European countries levels are as low as 0.05%. A blood alcohol concentration of 0.10% in a 68-kg (150-lb) person is the equivalent of about four drinks of 80 proof alcohoHc beverage or four 340-g (12-oz) beers in the body at the time of the test (see Beer Beverage spirits, distilled Wine). Ethanol is metabolized at the equivalent rate of about one drink per hour. 

Blood and urine are most often analyzed for alcohol by headspace gas chromatography (qv) using an internal standard, eg, 1-propanol. Assays are straightforward and lend themselves to automation (see Automated instrumentation). Urine samples are collected as a voided specimen, ie, subjects must void their bladders, wait about 20 minutes, and then provide the urine sample. Voided urine samples provide the most accurate deterrnination of blood alcohol concentrations. Voided urine alcohol concentrations are divided by a factor of 1.3 to determine the equivalent blood alcohol concentration. The 1.3 value is used because urine has approximately one-third more water in it than blood and, at equiUbrium, there is about one-third more alcohol in the urine as in the blood. 

Fig. 1. Blood alcohol concentration after consumption of an equal quantity of alcohol ia two different ways. A, three double Martiais within 30 min B, six...

Ethanol is classified for medical purposes as a central nervous system (CNS) depressant. Its effects—that is, being drunk—resemble the human response to anesthetics. There is an initial excitability and increase in sociable behavior, but this results from depression of inhibition rather than from stimulation. At a blood alcohol concentration of 0.1% to 0.3%, motor coordination is affected, accompanied by loss of balance, slurred speech, and amnesia. When blood alcohol concentration rises to 0.3% to 0.4%, nausea and loss of consciousness occur. Above 0.6%, spontaneous respiration and cardiovascular regulation are affected, ultimately leading to death. The LD50 of ethanol is 10.6 g/kg (Chapter 1 Focus On). 

Blood alcohol concentration can be determined directly by gas chromatography (Chapter 1). However, this approach is impractical for testing a driver on the highway. It requires that the suspect be transported to a hospital, where trained medical personnel can take a blood sample, then preserve and analyze it. 

Blood alcohol concentration and risk of crash. With increasing alcohol concentration in the blood, the risk of an automobile crash rises rapidly to 25 times the normal risk of a crash (that is, the risk with no alcohol consumption). 

Beta radiation Electron emission from unstable nuclei, 26,30,528 Binary molecular compound, 41-42,190 Binding energy Energy equivalent of the mass defect measure of nuclear stability, 522,523 Bismuth (m) sulfide, 540 Blassie, Michael, 629 Blind staggers, 574 Blister copper, 539 Blood alcohol concentrations, 43t Body-centered cubic cell (BCC) A cubic unit cell with an atom at each comer and one at the center, 246 Bohrmodd Model of the hydrogen atom... 

After oral ingestion, ethanol pharmacokinetics must take into account (1) Absorption from the gastrointestinal tract. Since ethanol is absorbed most efficiently from the small intestines, the rate of gastric emptying is an important factor that governs the rate of rise of blood alcohol concentration (BAC), i.e., the slope of the ascending limb of the BAC-time curve, and the extent of first pass metabolism of ethanol by the liver and stomach. (2) Distribution of ethanol in the body. Ethanol distributes equally in total body water, which is related to the lean body mass of the person, and (3) the elimination of ethanol from the body, which occurs primarily by metabolism in the liver, first to acetaldehyde and then to acetate [7]. 

Table 73-1 relates the effects of alcohol to the blood alcohol concentration (BAC). 

Specific Effects of Alcohol Related to Blood Alcohol Concentration (BAC)... 

The police may pull over a driver weaving erratically on the highway on suspicion of drunk driving. A police officer must confirm this suspicion by assessing whether the driver has a blood alcohol concentration over the "legal limit." The "Breathalyzer" test checks a person s breath using a redox reaction to determine blood alcohol concentration. This test was invented in 1953 by Robert Borkenstein, a former member of the Indiana State Police, and a professor of forensic studies. 

Blood Alcohol Concentration (%) after 7 oz of 80-proof vodka... 

Ethanol is readily measured in the blood and reported as milligrams per milliliter (mg per ml) of blood. Laws regulating drinking and driving identify a specific blood alcohol concentration (BAC) as unacceptable when operating a motor vehicle. Currendy most states set 0.08 or 0.1, which is equivalent to 80 mg/100 ml or 80 mg/dl of blood. Alcohol content of exhaled breath is about 0.05% of the BAC. 

Blood alcohol concentration (mg/dL) after the consumption of various amounts of alcohol (for an adult of about 150 lb). 

Blood alcohol concentration (BAG) is often based not on an actual sample of blood but rather on the concentration of alcohol in a sample of breath (Figure 3.3). Alcohol is volatile, and, as described by Henry s law, there is a constant relationship between the amount of alcohol vapor found in a volume of air (breath sample) and the amount of alcohol found in a volume of liquid (blood). All breath-testing equipment uses the blood-breath ratio of 2,100 1 for alcohol. This means that the amount of alcohol found in 2,100 milliliters of breath is equivalent to the amount of alcohol found in 1 milliliters of blood. 

Figure 3.3 A breathalyzer measures the amount of infrared (IR) energy absorbed by alcohol molecules. In this illustration, IR energy from a lamp (1) travels through a chamber (2) holding the subject s breath. As the IR energy exits the chamber, it is focused by a lens (3), passed through IR filters (4), and then converted into electrical signals (5). A computer (6) receives the electrical signals and computes the blood alcohol concentration.

Zedeck, Morris S. A Review and Analysis of the Use of the 2100 1 Blood-Breath Ratio for Determination of Blood Alcohol Concentration Scientific and Legal Issues. Expert and Scientific Evidence 3 (1996) 269-294. 

Some metabolism of ethanol by ADH occurs in the stomach in men, but a smaller amount occurs in women, who appear to have lower levels of the gastric enzyme. This difference in gastric metabolism of alcohol in women probably contributes to the sex-related differences in blood alcohol concentrations noted above. 

Table 23-1 Blood Alcohol Concentration ( ) and Clinical Effects in Nontolerant Individuals.

The most important goals in the treatment of acute alcohol intoxication are to prevent severe respiratory depression and to prevent aspiration of vomitus. Even with very high blood ethanol levels, survival is probable as long as the respiratory and cardiovascular systems can be supported. The average blood alcohol concentration in fatal cases is above 400 mg/dL however, the lethal dose of alcohol varies because of varying degrees of tolerance. 

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