Effect of Hyperthermia on Breath-Alcohol Analysis

Mild hyperthermia to the extent of a 2.5 degrees C increase above normal body temperature was produced by immersion of ethanol-intoxicated subjects in a warm water bath. Hyperthermia did not influence the blood-alcohol decay curve of the subjects. Hyperthermia did cause a significant distortion of the breath-alcohol decay curve, up to as much as a 23% increase above blood-alcohol concentration.

The magnitude of this distortion effect was calculated to be a 8.62% increase in breath-alcohol concentration over blood-alcohol concentration for each degree C increase in core body temperature. The forensic relevance of these results is that further support is given to previous recommendations that temperature monitoring be included in procedures for breath-alcohol analysis. This leads to the recommendation that mouth temperature be measured before breath sampling to screen for abnormal body temperature and to allow for potential use of a "temperature correction factor." This modification to existing analytical procedures would optimize the reliability of breath-ethanol analysis for prediction of blood-ethanol concentration.