If your Nevada DUI breath test showed an illegal blood alcohol content (BAC) of 0.08% or higher, you may be able to get the drunk driving charges dropped by arguing that your medical condition caused the inflated result. Specifically, disorders that affect your digestion or blood sugar can “trick” breathalyzers into returning falsely high BAC readings.
To help you understand how a medical condition might lead to an erroneous DUI breath test result, our Las Vegas DUI lawyers discuss the following below:
- 1. How Nevada DUI breath tests work
- 2. How medical conditions can cause unreliable Nevada DUI breath testing results
- Additional reading
1. How Nevada DUI breath tests work
Unlike a DUI blood test, a DUI breath test cannot directly measure the percentage of alcohol in your blood. Instead, DUI breath testing devices measure the amount of alcohol in your breath and mathematically convert it to a roughly equivalent BAC.
In Nevada, the evidentiary breath testing device currently in use is the Intoxilyzer 8000. The Intoxilyzer 8000 uses Infrared Spectroscopy to analyze the amount of alcohol in your breath.
1.1. The science of DUI breath testing
To get an accurate reading, the Intoxilyzer 8000 and other “Breathalyzers” must measure the alcohol present in your “deep lung” air. This is the air that is closest to your blood supply.
To understand why, consider that when we exhale, air emerges in the following “reverse” order:
- From the mouth/nasal area, then
- From the throat and upper airway, and finally
- From the alveoli, located deep within the lungs.
The alveoli are balloon-like sacs that inflate when we inhale and deflate when we exhale. The alveoli sit just above the capillaries, slender blood vessels no more than 1/1000 of a millimeter thick.
When we breathe, oxygen passes from the lungs into the capillaries. The capillaries, in turn, pass carbon dioxide and other wastes from the blood into the alveoli. These wastes are then gotten rid of when we exhale.
Because the capillaries are thin enough to allow the passage of oxygen and wastes, however, they can also pass a fraction of any alcohol present in the blood into the alveoli. This is why you are asked to blow hard when you take a breath test.
1.1.1. Not everyone can take breath tests
Older people and those with conditions that make it difficult to take a deep breath (such as asthma) may have trouble generating the volume of air required. Breath testing devices are calibrated to return an error message if enough air is not generated.
If you are unable to blow hard enough, you will usually be required to take a blood test instead.
2. How medical conditions can cause unreliable Nevada DUI breath testing results
In order to collect deep lung air, breathalyzers also collect air from your throat and mouth. This is because deep lung air must pass through your throat and your mouth in order for the device to capture it.
After ingesting alcohol, however, some of the alcohol remains in the mucosal linings of your mouth for a short period of time. This is known as “residual mouth alcohol.”
Imagine, for instance, that you swish wine around in your mouth at a wine tasting and then spit it out. A DUI breath test reading done immediately after would likely put you over the legal limit, even though you didn’t swallow and couldn’t, therefore, be drunk.
Mouth alcohol usually dissipates in 15-20 minutes or less. This is why Nevada law requires that you be observed for a 15-minute period before you are given an evidentiary breath test after a Nevada DUI arrest: It is to ensure that any residual mouth alcohol is completely gone at the time of your DUI breath test.
2.1. Digestive disorders
Mouth alcohol can also result from certain digestive disorders. In particular, conditions such as gastroesophageal reflux disease (GERD) and acid reflux – in which acid or alcohol from the stomach flows back into the esophagus – can trick a breathalyzer into thinking you are drunk.
Prosecutors claim that modern DUI breath testing equipment is sensitive enough to distinguish mouth alcohol from deep lung air. However, tests have shown that this is not always so.
2.2. Diets, diabetes, hypoglycemia and other conditions affecting blood sugar
Mouth alcohol also occurs in people who:
- suffer from diabetes or hypoglycemia, or
- are fasting, or
- are on severe high-protein, low-carbohydrate diets.
Healthy bodies normally get energy from carbohydrates in the diet. When we eat carbohydrates, our digestive systems break them down into sugars such as glucose – our bodies’ main energy source.
Glucose passes from the digestive tract into the bloodstream (which is why it’s often referred to as “blood sugar”). If we don’t eat enough carbohydrates to produce the blood sugar we need – because of dieting or starvation – our body must turn to our fat stores.
Fat is broken down in the liver and is turned into various chemical substances, including those known as “ketone bodies” or “ketones.”. In the absence of glucose, our bodies can burn ketone bodies for fuel. In the process of turning fats into ketones, however, the liver also produces a form of isopropyl alcohol (acetone).
Excess ketones (and isopropyl alcohol) are excreted in the urine and the urine and breath. Breath testing device manufacturers claim that their equipment can tell the difference between ethyl alcohol (the kind found in alcoholic beverages) and isopropyl alcohol; however, this is not always the case.
Thus people on high-protein or crash diets — or those who suffer from diabetes or hypoglycemia — are susceptible to false “positives” on Nevada DUI breath tests.
For more information on how medical conditions can serve as a defense to drunk driving charges in Nevada, see our related articles:
- How GERD, reflux, heartburn and hiatal hernia can “trick” DUI breath testing devices – a deep dive into how digestive disorders can influence the results of DUI breath tests
- Gut fermentation syndrome (also known as “auto-brewery” syndrome) – an examination of how gut fermentation syndrome can make a completely sober person fail a DUI breath test
- DUI and high-protein diets – a discussion on how what you eat can affect DUI breath test results
- Diabetes as a DUI Defense – an in-depth look into how diabetes can cause falsely high BAC readings on a breathalyzer
- How Hypoglycemia Can “Trick” a DUI breath test – an explanation of how breathalyzers can return inflated BAC readings due to hypoglycemia