Under The Microscope: “Letting go is hard!”

 

As a generalization, it has traditionally been assumed that  blood alcohol declines, after the peak is reached, at a rate of  around 15 mg/lOO ml/hour, but more recent research  indicates that this should be raised to  18.7. This applies to healthy adults who are not habituated  drinkers, and includes light to moderate drinkers and those  'binge drinkers' who may indulge heavily but intermittently.  The enormous number of publications on alcohol must be  consulted for details of the range of variation, but basically,  elimination can vary from about 12 to 27 mgI100 ml/hour. Taking the mean as around 18 mg, a man of average size  can therefore destroy about 9 g alcohol/hour, with a range  variation of between 7 and l6g. This is about the same as  the 'unit' of alcohol, a concept devised for convenience in estimating the daily or weekly intake of drinkers. A 'unit' is of  10 g and is contained (approximately) in half a pint of beer,  one single measure of spirits, or a standard glass of table wine.  The habituated drinker, the 'chronic alcoholic', can eliminate far faster than the average person, at least until he suffers severe liver damage in the later stages of his addiction.

Between 90 and 98 per cent of ingested alcohol is removed  from the blood by the liver, leaving a small residue to be  excreted unchanged by the kidneys, lungs, sweat, salivary  and mammary glands. The ethanol in glomerular filtrate is  in equilibrium with plasma, but as water is absorbed in the  renal tubules, the urine concentration is higher than the  blood level at the time of filtration, the ratio being approximately 123:lOO. This means, for example, that the legal  limit for driving in Britain of 80 mg1100 ml blood is taken  to be 107 mg1100 ml.  Unfortunately, it is obvious that, except in the highly unlikely circumstances of ureteric catheterization, the urine  concentration can never accurately represent the blood concentration at any given time. The blood concentration is -  almost never static, but is either rising or falling, so the  amount of alcohol in the glomerular filtrate is also constantly varying. It is being mixed in the bladder, however, with previously filtered urine and will also have that which is filtered  later added to it, until the bladder is emptied - so it can only  provide an average concentration for the time between two  micturitions. An added error is that urine produced before drinking began (and which was therefore alcohol-free) may  have already been in the bladder and will dilute the alcoholic  urine. In many countries, where urine is used for drink driving testing, the subject is instructed by the police to  empty his or her bladder before collection is made over the  subsequent hour, in order to avoid the dilution factor.  Breath is now used by many jurisdictions to measure  alcohol intake, either as a screening test before blood is taken  for analysis, or as an evidential method instead of blood or  urine. There is still some controversy over the scientific  accuracy of this method, but usually the results are so high  that errors are immaterial - or in marginal results, more  accurate blood testing is indicated.

Alveolar air at 37°C is in equilibrium with the pulmonary  capillary plasma alcohol, the ratio being about 2300:1, volume to volume, for blood as against breath. There is some  dispute as to the true ratio, which lies somewhere between  2 100 and 2400. If sufficiently deep exhalation is made to  drive out dead-space air, then the collected sample can be  analysed to give a measure of the blood alcohol, though  slight errors occur if there is incomplete elimination of dead space air and a drop in temperature as the air travels through  the dead space. In most countries using evidential breath  testing, however, the offence is not in having a breath-alcohol  level in excess of an equivalent blood level, but in having excess alcohol in the breath. This obviates defence ploys that  would attempt to throw scientific doubt on the relationship  between the two concentrations.

The concentration (often called the 'level') of alcohol in  blood, urine and breath is expressed by a variety of metric  units, which may lead to some confusion. The index most  widely used for blood, urine and other body fluids is the  weight of alcohol per volume of diluent - for example, mailgram’s per hundred millilitres (mg/100 ml). The expression  'decilitre' may be used instead of 100 ml (mg/dl). In some  countries in continental Europe, alcohol concentration is  expressed as 'promille', which is grams per litre (g/l), equivalent to milligrams per millilitre (mg/ml). Elsewhere, especially in the USA, a 'percentage' system is common, but can  be ambiguous as it does not intrinsically state whether the percentage is volume/ volume, volume /weight, weight/ weight  or weight/ volume. Unless otherwise stated, it is assumed to  be a weight /volume.

Breath is almost universally measured as micrograms per  hundred millilitres (kg1/100 ml). The matter of weight and  volume is important in respect of alcohol concentrations.  The specific gravity of alcohol is 0.79, the compound being  appreciably lighter than water. In alcoholic drinks, the  manufacturer's description and labelling is almost always 'volume/volume' (v/v), but physiological calculations are  made via the weight of alcohol in a given volume of body  fluid (w/v). Therefore, especially for stronger alcoholic  drinks, a conversion has to be made. For example, many  spirits, such as whisky, may be labelled as 40 per cent v/v,  but this would be only about 32 per cent weight/volume.  For weak drinks, such as beer, it is hardly worth correcting  the 4 per cent v/v, as calculations have a far greater intrinsic  error from other factors.

The practice of using 'units of alcohol' has become popular in recent years, not so much for calculating concentrations, but for approximate estimates of intake, in relation to  excessive drinking and the long-term medical consequences  of alcohol consumption. A 'unit' is of the order of 10 per  cent ethanol and very approximately delivered by 'one  drink', where this is either a half pint of beer, one glass of table wine or one small measure of spirits. For example, it  has been recommended that men should not exceed about  20 units per week and women 14, to avoid the risk of liver  damage. It has recently been claimed that from statistical  analysis of forensic autopsy material, the risk of coronary  heart disease can be reduced by drinking 2 units a day.

The most important statement in this respect is to stress  the utter unreliability and inaccuracy of attempting back calculations in either direction. Only gross approximations  can be achieved and no pretence at accuracy must be  offered. In this book, we are not concerned with the controversial problems of trying to estimate blood or breath  levels in living vehicle drivers at some time prior to an accident or other event, but with similar problems that can arise  in fatal cases, especially in relation to drink and driving. In  both criminal and civil disputes, evidence is often sought as  to the alcoholic state of the deceased at some material time,  based on calculations made from blood or urine alcohol analyses taken at autopsy. Less often, aviation, railway, driving and industrial fatalities may present the same potential  problem. Criminal proceedings may arise because of alleged  reckless driving on the part of another, when the drunken  state of the deceased victim may offer some defence. In civil  matters, often involving insurance companies, a significant  blood-alcohol level may be used as contributory negligence.

Whatever the reason, the pathologist must offer interpretations of alcohol levels found at autopsy with caution,  especially where retrospective calculations are requested.  Less often, the pathologist may be asked what blood or  urine levels might be expected at a certain time (for example,  at the time of death) given a description and timetable  of alcoholic drinks taken by the deceased. The same cautions against over precise calculations must be offered here.  In calculating approximate blood levels from a knowledge  of the drink taken, there are several methods in use: either  the well-known 'Widmark factor' or other calculations,  which are really modifications or simplifications of the  Widmark technique.

Formula  for calculating the total count of alcohol in the body,  from which knowing the body weight and assuming equilibration throughout the water compartment, the blood alcohol level could be derived.  The Widmark equation is: A = R X P X C, where A is  the total body alcohol, C the blood concentration, P the  body weight in kilograms and R a factor, which is 0.68 in men and 0.55 in women. The sex difference is due to the  different fat: water ratios, men having about 54 per cent  and women 44 per cent water partition by weight.

A useful approximate calculation, derived from Widmark,  is that an intake of 0.2 g of alcohol per kilogram body weight  is likely to result in a blood-alcohol concentration in men  of about 25 mg1100 ml.  The following facts are of use:

-     The average rate of decline of blood alcohol after the peak of the curve is reached, may be taken as about 15 mg/I 00 ml/hour, though recent research suggests 18 as more accurate;

-   The weight of alcohol imbibed may be calculated from knowledge of the v/v strength of the liquor and the amount taken. For example, if a 'double' British measure of 40 per cent v/v whisky is drunk, then 15 ml will contain (40 X 0.8) = 32 per cent alcohol w/v in 15ml = 4.8g;

-          The weight of alcohol/kg body weight is calculated;

-          A ratio of 0.2 g alcohol/kg body weight will produce a blood level of approximately 25 mg1100 ml in a man, assuming an empty stomach;

-          In women, the level so produced may be 20-25 per cent higher;

-          If only beer is drunk, the peak will be considerably less, sometimes only 50 per cent that produced from wine or spirits;

-         Drinking during or after a meal markedly flattens the blood-alcohol curve;

The pathologist is frequently asked in either written opinions or in court testimony to give an estimate of the behavioural state of a victim at a certain level of blood alcohol or  after having taken a specified amount of drink. Though he  is usually not qualified as an expert on alcoholism in any clinical sense, he will be a medical practitioner with general  knowledge and some personal experience of alcoholic  behaviour, from his pre-pathology years.

He thus can give a  general opinion to assist the court, but unless he has special  experience of the matter, he should not extend himself into  detailed clinical expositions, which are the province of the psychiatrist with an interest in alcoholism, a police surgeon  or a casualty officer, all of whom deal frequently with  drunken patients. A general level of knowledge can be  offered to the lawyer, police or court, however, especially in  respect of the usual level of capability and consciousness at  different blood-alcohol levels.

 

 

Acknowledgements:

www.aived.nl    AIVD – @Erik Akerboom ©

www.politie.nl  Politiekorpschef  @Janny Knol©

www.politie.nl WEB Politie - @Henk van Essen©

 

Bibliography:

 

1.    Criminal Investigations – Crime Scene Investigation.2000

 

2.    Forensic Science.2006

 

3.    Techniques of Crime Scene Investigation.2012

 

4.    Forensics Pathology.2001

 

5.    Pathology.2005

 

6.    Forensic DNA Technology (Lewis Publishers,New York, 1991).

 

7.    The Examination and Typing of Bloodstains in the Crime Laboratory (U.S. Department of Justice, Washington, D.C., 1971).

 

8.    „A Short History of the Polymerase Chain Reaction". PCR Protocols. Methods in Molecular Biology.

 

9.    Molecular Cloning: A Laboratory Manual (3rd ed.). Cold Spring Harbor,N.Y.: Cold Spring Harbor Laboratory Press.2001

 

10.   "Antibodies as Thermolabile Switches: High Temperature Triggering for the Polymerase Chain Reaction". Bio/Technology.1994

 

11.   Forensic Science Handbook, vol. III (Regents/Prentice Hall, Englewood Cliffs, NJ, 1993).

 

12.   "Thermostable DNA Polymerases for a Wide Spectrum of Applications: Comparison of a Robust Hybrid TopoTaq to other enzymes". In Kieleczawa J. DNA Sequencing II: Optimizing Preparation and Cleanup. Jones and Bartlett. 2006

 

13.   Nielsen B, et al., Acute and adaptive responses in humans to exercise in a warm, humid environment, Eur J Physiol 1997

 

14.   Molnar GW, Survival of hypothermia by men immersed in the ocean. JAMA 1946

 

15.   Paton BC, Accidental hypothermia. Pharmacol Ther 1983

 

16.   Simpson K, Exposure to cold-starvation and neglect, in Simpson K (Ed): Modem Trends in Forensic Medicine. St Louis, MO, Mosby Co, 1953.

 

17.   Fitzgerald FT, Hypoglycemia and accidental hypothermia in an alcoholic population. West J Med 1980

 

18.   Stoner HB et al., Metabolic aspects of hypothermia in the elderly. Clin Sci 1980

 

19.   MacGregor DC et al., The effects of ether, ethanol, propanol and butanol on tolerance to deep hypothermia. Dis Chest 1966

 

20.   Cooper KE, Hunter AR, and Keatinge WR, Accidental hypothermia. Int Anesthesia Clin 1964

 

21.   Keatinge WR. The effects of subcutaneous fat and of previous exposure to cold on the body temperature, peripheral blood flow and metabolic rate of men in cold water. J Physiol 1960

 

22.   Sloan REG and Keatinge WR, Cooling rates of young people swimming in cold water. J Appl Physiol 1973

 

23.   Keatinge WR, Role of cold and immersion accidents. In Adam JM (Ed) Hypothermia – Ashore and Afloat. 1981, Chapter 4, Aberdeen Univ. Press, GB.

 

24.   Keatinge WR and Evans M, The respiratory and cardiovascular responses to immersion in cold and warm water. QJ Exp Physiol 1961

 

25.   Keatinge WR and Nadel JA, Immediate respiratory response to sudden cooling of the skin. J Appl Physiol 1965

 

26.   Golden F. St C. and Hurvey GR, The “After Drop” and death after rescue from immersion in cold water. In Adam JM (Ed). Hypothermia – Ashore and Afloat, Chapter 5, Aberdeen Univ. Press, GB 1981.

 

27.   Burton AC and Bazett HC, Study of average temperature of tissue, of exchange of heat and vasomotor responses in man by means of bath coloremeter. Am J Physiol 1936

 

28.   Adam JM, Cold Weather: Its characteristics, dangers and assessment, In Adam JM (Ed).Hypothermia – Ashore and Afloat, Aberdeen Univ. Press, GB1981.

 

29.   Modell JH and Davis JH, Electrolyte changes in human drowning victims.Anesthesiology 1969

 

30.   Bolte RG, et al., The use of extracorporeal rewarming in a child submerged for 66 minutes. JAMA 1988

 

31.   Ornato JP, The resuscitation of near-drowning victims. JAMA 1986

 

 

 

32.   Conn AW and Barker CA: Fresh water drowning and near-drowning — An update.1984;

 

33.   Reh H, On the early postmortem course of “washerwoman’s skin at the fingertips.” Z Rechtsmed 1984;

 

34.   Gonzales TA, Vance M, Helpern M, Legal Medicine and Toxicology. New York, Appleton-Century Co, 1937.

 

35.   Peabody AJ, Diatoms and drowning – A review, Med Sci Law 1980

 

36.   Foged N, Diatoms and drowning — Once more.Forens Sci Int 1983

 

37.   "Microscale chaotic advection enables robust convective DNA replication.". Analytical Chemistry. 2013

 

38.   Sourcebook in Forensic Serology, Immunology, and Biochemistry (U.S. Department of Justice, National Institute of Justice, Washington, D.C.,1983).

 

39.   C. A. Villee et al., Biology (Saunders College Publishing, Philadelphia, 2nd ed.,1989).

 

40.   Molecular Biology of the Gene (Benjamin/Cummings Publishing Company, Menlo Park, CA, 4th ed., 1987).

 

41.   Molecular Evolutionary Genetics (Plenum Press, New York,1985).

 

42.   Human Physiology. An Integrate. 2016

 

43.   Dumas JL and Walker N, Bilateral scapular fractures secondary to electrical shock. Arch. Orthopaed & Trauma Surg, 1992; 111(5)

 

44.   Stueland DT, et al., Bilateral humeral fractures from electrically induced muscular spasm. J. of Emerg. Med. 1989

 

45.   Shaheen MA and Sabet NA, Bilateral simultaneous fracture of the femoral neck following electrical shock. Injury. 1984

 

46.   Rajam KH, et al., Fracture of vertebral bodies caused by accidental electric shock. J. Indian Med Assoc. 1976

 

47.   Wright RK, Broisz HG, and Shuman M, The investigation of electrical injuries and deaths. Presented at the meeting of the American Academy of Forensic Science, Reno, NV, February 2000.