Which sample minimizes dilution from upper airway breath?

Which sample minimizes dilution from upper airway breath?

• A. Saliva
• B. Alveolar (deep lung) sample
• C. Blood sample
• D. Urine sample

Answer: (B)

The important idea is that the most accurate breath sample for estimating blood alcohol concentration comes from alveolar air—the air from deep in the lungs that has come into equilibrium with the bloodstream. Alveolar breath reflects ethanol in arterial blood because it has exchanged across the alveolar-capillary membrane, so it mirrors the true BAC and isn’t diluted by air from the mouth or throat. That’s why collecting an alveolar, end-tidal breath minimizes the impact of upper airway contaminants and dilution. Saliva can contain alcohol from recent rinsing, chewing, or sipping and doesn’t reflect BAC; a blood sample is not a breath sample (though it measures BAC directly); urine shows excreted alcohol/metabolites and isn’t representative of current breath alcohol. So using deep-lung alveolar breath provides the most reliable, minimally diluted measurement.

The important idea is that the most accurate breath sample for estimating blood alcohol concentration comes from alveolar air—the air from deep in the lungs that has come into equilibrium with the bloodstream. Alveolar breath reflects ethanol in arterial blood because it has exchanged across the alveolar-capillary membrane, so it mirrors the true BAC and isn’t diluted by air from the mouth or throat. That’s why collecting an alveolar, end-tidal breath minimizes the impact of upper airway contaminants and dilution. Saliva can contain alcohol from recent rinsing, chewing, or sipping and doesn’t reflect BAC; a blood sample is not a breath sample (though it measures BAC directly); urine shows excreted alcohol/metabolites and isn’t representative of current breath alcohol. So using deep-lung alveolar breath provides the most reliable, minimally diluted measurement.