Airflow obstruction and roadside breath alcohol testing.

FIGURE 1. Bar graph shoiwing distribution oil FVC in study population. Heavily shaded sections represent the three subjects who could not dot the test. Lightly shaded sections represent asthmatic patients. Clear sections represent COPD patients. communications to the editor Communications for this section will be published as space and priorities permit. The comments should not exceed 350 words in length, with a maximum office references; one figure or table can be printed. Exceptions may occur under particular circumstances. Contributions may include comments on articles published in this periodical, or they nuzy be reports of unique educational character. Specc flc permission to publish should be cited in a covering letter or appended as a postscript. We have frequently been asked to give a medicolegal opinion regarding claims of inability' to provide an adequate breath sample to activate a portable roadside breath alcohol testing device because of asthma or chronic obstructive pulmonary disease (COPD). We examined the physical characteristics of a commonly used hand-held breath alcohol screening device (ALERT, model J3A; Alcohol Countermeasures, Mississauga, Ont) and evaluated the ability of patients with asthma or COPD to perform an acceptable test. The roadside testing device we used measures ethanoA in exhaled gas; this reflects the blood alcohol level. It uses a disposable mouthpiece with orifice diameters ofapproximately 3.3 mm, and it has an oiutflow orifice oif approximately 1.2 mm. It has a series of colored lights on the tipper surface. The operational light indicates that the machine is ready to receive the exhaled sample. If an adequate flow of exhaled air passes across the inflow orifice over an adequate length of time, the operational light is replaced by a red, amber, or green light, indicating " fail, " " warn:' oir " pass:' respec-tivell ; regarding alcohol level. If critical flow is not maintained for the lull time, no result is given. If a subject cannot provide an adequate sample in several attempts, he may be charged with " failure to provide a sample. " We connected the testing device N U M B E R 0 F S U B J E C T S through a pressure transducer and flowmeter tot a soiurce oil air. Ve found that at ambient room air temperature and pressure a critical flow of 6.6 Ijmin (1 10 ml/s) sustained loir a period of 5.5 s at a critical pressure of 15 to 17 cm H2O …