Maryland DUI Breath Tests and Sleep Apnea Errors

 Posted on December 12, 2025 in Drunk Driving

Suppose you are a Maryland driver who is stopped on suspicion of DUI. Since you have not been drinking or have only had a small amount of alcohol, like one beer, you do not hesitate to agree to a breathalyzer – the Intox EC/IR-II, which is the primary breathalyzer used in the state. You assume you will be immediately cleared and sent on your way, but the machine prints out a BAC far higher than you expected.

If you have a medical condition known as sleep apnea, you should know that this condition can disrupt normal airflow, creating "spike" readings on the breathalyzer.  According to the American Medical Association, sleep apnea is extremely common across the United States, affecting one-third of all adults. Unfortunately, the condition is largely undiagnosed, with up to 80 percent of moderate to severe cases going undetected.

More men suffer from sleep apnea than women, and the prevalence increases with age, obesity, and diabetes. If you suffer from sleep apnea or believe you might, speaking with an experienced Centreville, MD DUI lawyer can be extremely beneficial. Many Maryland defense lawyers are calling on sleep specialists to help juries understand why the test results may not actually reflect impairment.  

How Do Breathalyzer Tests Misread Sleep Apnea?

The Maryland Intox EC/IR-II is state-approved (Maryland Courts and Judicial Proceedings Article, Section 10-302-10-304) and relies on infrared and electrochemical sensors to estimate alcohol concentration. Although the device was designed to detect "interfering substances," with complex compounds or consistent medical issues, that detection is far from perfect. The breathalyzer results from this machine assume three things:

• Continuous airflow
• Full alveolar (deep lung) sample
• Stable breath pressure and volume

The device does not directly misread sleep apnea, but the condition, along with the associated symptoms (acid reflux, breathing changes, diabetes, fatigue), creates certain conditions, including erratic breathing, mouth alcohol, and metabolic changes that skew the numbers. These conditions can compromise the instrument's accuracy, leading to falsely high readings by mimicking the presence of alcohol or altering the blood-to-breath ratio, thereby challenging the machine’s core assumptions.

How Sleep Apnea-Related Issues Interfere with BAC Readings

Sleep apnea causes interrupted breathing, which often goes hand-in-hand with acid reflux (GERD) and belching. These actions bring the stomach contents into the mouth. Since these stomach contents contain residual alcohol or volatile compounds, the EC/IR-II’s alcohol sensors can be tricked into a falsely high BAC reading.  

Because sleep apnea involves breathing cessations, erratic breathing during a BAC test can lead to an "insufficient sample" error or an inconsistent deep lung sample, adversely impacting the BAC numbers. Metabolic issues like diabetes often occur alongside sleep apnea, producing ketones (acetone) in the breath. Breathalyzers can sometimes confuse acetone with alcohol.

The breathalyzer machine itself relies on standard blood to breath alcohol (partition ratio), but weight, gender, body temperature, and medical conditions like sleep apnea or asthma can significantly alter this ratio, making the readings unreliable. Sleep apnea creates an environment that is ripe for breathalyzer errors, making the machine potentially misinterpret normal bodily functions or compounds as higher levels of alcohol.

Why Breathalyzer Machine Errors Matter

The Maryland Court of Appeals requires breath test results to be scientifically reliable, properly administered, and supported by a consistent sample curve. Challenges to the results can be based on instrument malfunction or miscalibration, or an officer's failure to ensure a valid deep lung sample. Challenges can also be based on physiological interference with accurate readings. These irregularities can affect the admissibility of the BAC at trial.

Contact an Anne Arundel County, MD DUI Attorney

If you have been charged with DUI in Maryland and suffer from sleep apnea, your breath test numbers may not tell the whole story. A skilled Centreville, MD criminal defense lawyer from Henley & Henley, Attorneys at Law can work closely with medical experts to expose errors in Intox EC/IR-II readings and challenge unreliable BAC readings. Our attorneys have more than 50 years of combined legal experience and will aggressively work to minimize the consequences of DUI charges. We usually offer a flat fee as well. Call 410-280-0530 to schedule your initial attorney meeting.