Duplicate breath alcohol analysis: some further parameters for evaluation

An individual exhaling into a breath alcohol instrument produces a breath alcohol concentration (BrAC) profile which is a continuous function of time. Microprocessor based breath alcohol instruments provide the capability to collect and store the BrAC profile data in discrete format. The present study collected duplicate BrAC profile data arrays on 11 field tested subjects and 16 experimentally tested subjects. The field subjects provided duplicate breath samples under normal field conditions. The experimental group provided one sample following normal breathing and one following breath holding. Each profile was subjected to ten different mathematical procedures. The duplicate results were then evaluated by a t-test for paired data. The experimental group showed statistical significance (P less than 0.01) for all but one mathematical parameter evaluated. The field group showed no statistical significance on any of the mathematical parameters. The results showed that BrAC profiles can be evaluated in a variety of ways and provide an index for detecting differences in breathing pattern prior to breath exhalation. The field data showed remarkable reproducibility by all mathematical indices. The results have forensic as well as physiological implications.