Spirometric testing and the breathalyser
CMAJ 1997;157:510
Our recent criminal court experience supports the caution to physicians contained in "Don't use medical excuses to escape breathalyser, MDs warn" (CMAJ 1997;156:157).
A 61-year-old man was arrested for operating a motor vehicle while impaired by alcohol. At the police station he did not provide a suitable breath sample for the breathalyser, citing "shortness of breath" from smoking and work in a dusty area that day. The breathalyser technician noted that the accused did not blow hard enough to raise the piston, and no exhalation or venting was detected after several attempts.
A physician wrote that the accused had "a degree of chronic destructive [sic] lung disease," and with no objective spirometric data concluded that it would be difficult for the accused to provide a breath sample for the breathalyser.
At trial, a videotape of the accused taken at the police station showed he had no apparent breathing problems while walking or talking. The physician testified that the accused had some degree of chronic obstructive pulmonary disease (COPD), but upon cross-examination admitted it was not severe enough to warrant spirometric testing.
In a study of 10 patients with known COPD, all were able to provide an adequate sample for the breathalyser. These patients (aged 56 to 78 years) had a forced expiratory volume in 1 second (FEV1) between 0.46 and 1.86 L and a ratio of FEV1 to forced vital capacity of from 0.19 to 0.53.1
Our experience is that objective spirometric testing, showing significantly diminished values, is required for reliable testimony in these types of cases. In this case, the accused was convicted of failing to provide a breath sample.
James G. Wigmore, BSc
Michael Corbet, PhD
Steven Lintlop, MSc
Toxicology Section
Centre of Forensic Sciences
Ontario Ministry of the Solicitor General
and Correctional Services
Toronto, Ont.
Reference
- Wilson A, Sitar DS, Molloy WD, McCarthy D. Effect of age and chronic obstructive pulmonary disease on the breathalyser estimation of blood alcohol level. Alcohol Clin Exp Res 1987;11(5):440-3.
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