title: Differences between the measured blood ethanol concentration and the estimated concentration by Widmark's equation in elderly persons.
abstract: BACKGROUND
  The Widmark's equation (C [BAC]=A/p×r) is the most commonly used formula in legal medicine to estimate the blood alcohol concentration (BAC) from the amount of ingested ethanol and vice versa. Within a drinking experiment with a target BAC of 1.2 g/kg, a 75-year-old participant reached a maximum BAC of 1.83 g/kg and showed signs of severe ethanol intoxication, while the other nine subjects (age: 19-31 years) had BACs close to the target BAC. This incident brought up the question, if the Widmark's equation is an appropriate tool for aged persons.
  
  
  METHODS
  A drinking experiment with 50 elderly voluntary test persons (22 males, 28 females, mean age and range [males]: 69.7 years, 60-84 years, mean age and range [females]: 68.5 years, 61-78 years) was performed. The amount of ethanol leading to a BAC of 0.6 g/kg was estimated individually using the Widmark's equation (used Widmark factors: 0.7 for males, 0.6 for females). After drinking, the blood ethanol concentrations were measured using headspace gas chromatography/flame ionization detection.
  
  
  RESULTS
  The measured maximum BACs of the elderly participants were significantly higher (α=0.01) than the target BAC (mean maximum BAC and range: 0.627 g/kg, 0.3-0.81 g/kg, for males: 0.616 g/kg, 0.32-0.78 g/kg, for females: 0.635 g/kg, 0.3-0.81). The calculated Widmark factors showed a high coefficient of variation (for males: 0.7±0.138 [0.55-1.2, CV: 19.7%], for females 0.59±0.119 [0.46-1.08, CV: 20.2%]).
  
  
  CONCLUSIONS
  The results demonstrate that BAC calculations by Widmark's equation in elderly individuals may be complicated by a high variation of Widmark factors. There is a tendency to an elevation of the actual BAC with increasing age.
authors.affiliation: Institute of Forensic Medicine, University Medical Center Freiburg, Albertstraße 9, 79104 Freiburg, Germany. Electronic address: lena.bielefeld@uniklinik-freiburg.de.
authors.forename: Lena
authors.initials: L
authors.lastname: Bielefeld
authors.affiliation: Institute of Forensic Medicine, University Medical Center Freiburg, Albertstraße 9, 79104 Freiburg, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Auwärter
authors.affiliation: Institute of Forensic Medicine, University Medical Center Freiburg, Albertstraße 9, 79104 Freiburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Pollak
authors.affiliation: Institute of Forensic Medicine, University Medical Center Freiburg, Albertstraße 9, 79104 Freiburg, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Thierauf-Emberger
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000435:Alcoholic Intoxication / Q000097:blood; D000067401:Blood Alcohol Content; D002492:Central Nervous System Depressants / Q000493:pharmacokinetics*; D000431:Ethanol / Q000493:pharmacokinetics*; D005260:Female; D005410:Flame Ionization; D053593:Forensic Toxicology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D055815:Young Adult
chemical_list: D000067401:Blood Alcohol Content; D002492:Central Nervous System Depressants; D000431:Ethanol
keywords: Blood ethanol concentration; Elderly persons; Widmark's equation