Myth #12: Breath Test — Hematocrit Is Irrelevant To The Result
So you ask, what is hematocrit?
The hematocrit represents the fraction of whole blood composed of red cells and is correlated with the aqueous content of blood. The higher the hematocrit, the lower the concentration of water in blood, and vice versa. The average hematocrit for normal, healthy males is 47%, with a range of 40-54%; for females the average is 42% and the range is 36-47%. Since ethanol dissolves almost entirely in the aqueous component of blood, two individuals with identical actual BAC’s but with different hematocrits would be expected to produce different Breathalyzer results.
Defending against DUI / DWIThe person with the higher hematocrit, and therefore lower blood-water content, would necessarily be characterized by a higher concentration of ethanol in the aqueous component of his/her blood and consequently, by a higher Breathalyzer reading. Given that the Breathalyzer uses only one partition ratio, Smith and Payne et al. have predicted that the normal variation in hematocrit can produce errors in breath test results in the 10 to 14% range. Next article: Index: |
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