To this point I have discussed a number of reasons why a person should be skeptical of the results obtained by a breathalyzer. Unfortunately, many judges are not as skeptical so one must be educated on these matters in order to make an informed and voluntary decision regarding whether to blow or not to blow. Before leaving the issue of the reliability (or lack thereof) of the machine I want to discuss the difference between absorption and post absorption and how that affects your true BAC versus your machine number.
A common problem that a driver may run into is being tested by the machine shortly after leaving a restaurant or drinking event. If a driver is stopped shortly after consuming alcohol, chances are the driver is in the absorptive phase. That is, his body is still absorbing the alcohol that was recently consumed. The absorptive phase generally lasts from 45 minutes to as much as two hours after drinking has abated with peak absorption generally at one hour whereupon the driver has reached equilibrium. Equilibrium meaning that the alcohol is evenly dispersed throughout the driver’s body. The biggest factor that controls absorption is food intake. Food in the stomach can have a significant impact on when alcohol passes from the stomach to the small intestine for absorption.
In the absorptive phase, the alcohol in the body is not evenly distributed throughout the body but rather resides in higher doses in different parts of the body. In the post absorptive phase, the alcohol content has evened out and is more uniform throughout. In the absorptive phase, one of the most significant aspects is that alcohol content in arterial (artery) blood will be higher than in venous (vein) blood. When you give a blood sample it is drawn from a vein. During peak absorption arterial BAC can be as much as 50-60 percent higher than venous blood. So, why is this important in breath cases?
This is very important because the alveolar sacs of the lungs where the air exchange takes place between the blood and the lungs are immersed in arterial blood, not venous blood; therefore the breath sample obtained by the machine will be based upon pulmonary BAC which during the absorption phase will be markedly higher than the veinous BAC if a blood draw was performed.
This fact regarding absorption stage is well known and supported among the experts in the field including Dr. Kurt Dubowski, a prominent professor at the University of Oklahoma, however, if you were to ask a breath operator about this point, he would look at you like you had 3 eyes.
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