Myth #9: Breath Test — GERD Cannot Affect The Breath Test
It was reported that approximately 7% of US adults experience daily heartburn so GERD probably represents a common disorder, even among those who might submit to a breath-alcohol test. About 90 min after the end of drinking, when the BAC-profile enters the post-absorptive phase, the concentration of alcohol in the stomach should be roughly the same as that in the peripheral venous blood. Accordingly, if gastric reflux occurred 90 min or more after the end of drinking it should not compromise the results of an evidential breath-alcohol test because the concentration of alcohol in the gastric fluid at this time is relatively low and probably similar to that of mucous secretions in the mouth and upper-airway.
Stergios Kechagias, Kjell-Ake Jonsson, Thomas Franzen, Lars Andersson & Alan Wayne Jones, Reliability of Breath-Alcohol Analysis in Individuals with Gastroesophageal Reflux Disease, 44 (4) J. Forensic Sci. 814, 814 (Jul. 1999)
Defending against DUI / DWIOf course, this quote implies that the converse may be true. If the gastric reflux occurs during absorption, which according to studies by Dr. Dubowski cited above, can take over 2 1/2 hours, then it could affect the breath reading. Obviously, the risk of gastric reflux increasing the result of a breath-alcohol test will be greatest shortly after the end of drinking when the concentration of alcohol in the stomach is at its highest. The mandatory 15 min observation period still remains an important element of the evidential breath-alcohol test protocol because this can help to rebut allegations that gastric reflux occurred. Notes1. Other legal treatises containing helpful information include Paul C. Gianelli and Edward J. Immwinkelreid, Scientific Evidence, (3rd ed. 1999), Lawrence Taylor, Drunk Driving Defense (New York: Aspen Law and Business 5th ed. 2000), Don Nichols and Flem Whited, Drinking/Driving Litigation Criminal and Civil (2nd ed.1998), John Tarantino, Defending Drinking Drivers, (Heidi Lowry and Erin Tackitt eds., rev. 20 2004) and Richard Erwin, Defense of Drunk Driving Cases, Criminal and Civil (2nd ed. 2004). 2. Terms like “standard of deviation,” “coefficient of variation,” and normal or Gaussian distribution are common in scientific articles dealing with measuring alcohol in the body. These terms, and the algebraic equations that accompany them, can be intimidating to one who has not taken a basic course in statistics. Two relatively easy to comprehend books for the novice are Larry Gonick and Woollcott Smith, The Cartoon Guide to Statistics (1993) and Lloyd Jaisingh, Ph. D., Statistics for the Utterly Confused (2000). The essential concepts are explained in a way that is easy to understand for the non-scientist or non-statistician. In other words, lawyers can comprehend these books! In a sample population, the standard deviation or “s” is the average deviation from the mean. The mean, or average, is the sum of all of the samples divided by the number of samples. Each sample is then subtracted from the mean and squared. The sum of the squares of the differences is divided by the number of samples minus 1. The square root of that number is the standard deviation. Simple, right? Let’s take a sample composed of 8 numbers: 10; 12; 14; 15; 17; 18; 18; and 24. The sum of these numbers is 128. 128 divided by 8 equals the mean or 16. 10 minus 16 equals -6. -6 squared equals 36. This is repeated for each number. So the number, difference from the mean and square of the difference for each remaining number in the sample is 12, -4, 16; 14, -2, 4; 15, -1, 1; 17, 1,1; 18, 2, 4; 18, 2, 4; and 24, 8, 64. These squares are all added. 36+16+ 4+1+1+4+4+64 for a total of 130. That total is divided by the number of numbers in the sample minus 1 or 8-1 or 7. 130 divided by 7 equals 18.57142. The square root of that is 4.309. That is the standard deviation. Voila! We are now statisticians! Effective DUI / DWI DefenseThe coefficient of variation is the relation between the standard deviation and the mean, expressed as a percentage. In our sample, for example, the standard deviation of 4.309 divided by the mean, 16, times 100, and expressed as a percentage is 26.934 percent. A normal or Gaussian distribution is basically a bell curve, where the greatest number of numbers in the sample are closest to the mean and drop off as they are further from it. It is named for Johann Carl Friedrich Gauss, a 17th-century mathematician who is credited with having first recognized this concept. In a population with a Gaussian distribution, as you move away from the mean in both directions, generally 68.2 percent of the population will be within one standard deviation from the mean, 95.5 percent of the population will be within 2 standard deviations and 99.7 percent of the population will be within 3 standard deviations from the mean. 3. This is computed by multiplying the standard deviation of 241.5 x 2.58 = 623.7. Subtracting this figure from 2280 equals 1656.93. Thus the partition ratio of 1656.93 is reached for a confidence level of 99 percent. Next article: Index: |
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