Updating the widmark equation

Although there is some absorption from the stomach, it is significantly slower than that from the intestine. For criminal cases, the settings may be adjusted to encompass 95% of the population by spanning two (2) standard deviations.

Higher ethanol concentrations in the gastrointestinal tract cause a greater concentration gradient and therefore hasten the rate of absorption. Peak blood-alcohol levels can vary between different types of alcoholic beverages. As fat constitutes a higher proportion of the body weight in women than in men, the resultant volume of distribution of ethanol in women is lower than that of men. D., Page 251-252, Harcourt Brace Jovanovich, Philadelphia (1992)). Widmark, Principles & Applications of Medicalegal Alcohol Determinations (Scitran, Santa Barbara, CA, trans.)(Biomedical Pubs.: Davis, CA 1981). Watson published the following values for "r" in Prediction of Blood Alcohol Concentration in Human Subjects: Updating the Widmark Equation, 42:7 J. Conversely, the maximum "r" distribution constant is factored with the minimum elimination rate to achieve the maximum blood alcohol level. Dubowski published the following values in Human Pharmacokinetics of Ethanol. Peak Blood Alcohol Concentrations and Elimination in Male and Female Subjects, 5:4 Alcohol Technical Rep. Alcohol is primarily eliminated by the liver by enzymatic oxidation. Thus, 95% of the population should fall within the following range: DUI Professional combines the minimum "r" distribution constant with the maximum elimination rate to achieve the minimum blood alcohol level. Dubowski, 134 adult men were studied in the post-absorptive state and reported an elimination rate of 0.01494% per hour ( /- 0.00450 standard deviations), with a range of values from 0.006 to 0.028% per hour.

The absorption process continues until the alcohol concentration in the blood and that in the gastrointestinal tract are at equilibrium. Accordingly, absorption of a given amount of ethanol will result in a higher blood-alcohol level in women than in men of equal weight. The original values proposed by Widmark were 0.68 for men and 0.55 for women. More lean, muscular subjects will have a higher "r" value while fatter or more flaccid subjects will have a lower "r" value. REFERENCE: K Dubowski Human Pharmacokinetics of Ethanol. Peak Blood Alcohol Concentrations and Elimination in Male and Female Subjects, 5:4 Alcohol Technical Rep. Less than 10% is excreted from breath, perspiration and urine. Conversely, the maximum "r" distribution constant is factored with the minimum elimination rate to achieve the maximum blood alcohol level. This constitutes an average of approximately 0.015% per hour.

Blood alcohol concentrations (BAC) in children after consumption of different numbers of standard drinks of alcohol have not previously been estimated.

The updated Widmark equation to estimate BAC was modified to take account of the differing body composition (total body water) and accelerated rate of ethanol elimination of children.

The estimated BAC for children after consuming just three standard drinks within a 2-hour period was between 80 and 139 mg/d L for boys aged 9-13 and for girls aged 9-17, indicating substantial potential alcohol impairment.

At five drinks within 2 hours, the level used to define binge drinking among college students, children aged 9-13 were estimated to have BACs two to three times the adult legal limit for intoxication of 80 mg/d L.The aim of the present study is to modify these equations in order to generate BAC estimates that are more developmentally appropriate for children and early adolescents.It will then be possible to determine the appropriate number of drinks to ask about in questions assessing child or adolescent “binge” drinking.Binge drinking assessment in children and adolescents requires substantially lower cut-points than those used for college students.Binge drinking should be defined as 3 or more drinks for 9-13 year olds, as 4 or more drinks for boys and 3 or more drinks for girls aged 14 or 15, and as 5 or more drinks for boys and 3 or more drinks for girls aged 16 or 17.The modified formula was then used with NHANES 1999-2002 data to estimate BAC for over 4,700 male and female children and adolescents at each age from 9 through 17 years old for intake levels from one through five standard drinks.

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