Journal of Chnical Forensic Medicine (1998) 5, 4 5 ~ 8 © APS/Harcourt Brace & Co. Ltd 1998 ORIGINAL COMMUNICATION Breath testing in patients with respiratory disability M. S. Odell*, C. E McDonald*, J. Farrar J. S. Natsis*, J. F. Pretto t * Victorian Insfitute of Forensic Medicine, Southbank Victoria, Australia ~Austin and Repatriation Medical Centre, Heidelberg Victoria, Australia ~ Victoria Police, Brunswick Victoria, Australia SUMMARY. The presence of chronic respiratory disease is sometimes claimed as a defence by drivers who refuse or fail a breath test. Trials have been conducted with two breath analysis instruments used in the state of Victoria, Australia in order to determine the respiratory parameters compatible with a satisfactory test. Patients with restrictive and obstructive conditions participated in the trial that was conducted in the respiratory unit of a large teaching hospital. The results showed that the evidential breath analyzer currently used in Victoria was able to accept breath samples from subjects at the limit of respiratory function likely to be encountered in drivers. It was also found that a subject capable of providing a breath sample for the current screening device should also be able to provide an evidential sample. The trials provided useful information in evaluating defences of inability to provide a breath sample due to respiratory incapacity. Journal of Clinical Forensic Medicine (1998) 5, 45-48 INTRODUCTION In Victoria, breath testing for alcohol is carried out under provisions of the Road Safety Act 1986.1 This act provides for compulsory breath testing of drivers under certain circumstances. While inability to provide a suitable breath sample results in a required blood sample, refusal to provide a breath sample is an offence under the Act and carries a heavy penalty. Notwithstanding the requirement for a blood sample to be provided in the event of a failed breath test, a number of drivers have attempted to use the presence of chronic respiratory disease as a defence against the charge of refusing a breath test. This trial was carried out in an attempt to quantify the minimum respiratory effort required for a satisfactory breath test Dr Morris S. Odell BE(Hons), MBBS, FRACGP, DMJ, Forensic Physician, Victorian Institute of ForensicMedicine, 57-83 Kavanagh Street, Southbank Victoria, 3006, Australia Dr Christine E McDonald MBBS(Hons), FRACP, PhD, Respiratory Physician,Austin and Repatriation Medical Centre, John Farrar BSc(Hons),ForensicOffice1; Traffic Alcohol Section, Victoria Police,20 Dawson Street, Brunswick Victoria 3056, Australia, James S. Natsis, TraineeMedical Scientist,Austin and Repatriation Medical Centre, Jeff J. Pretto BAppSe, Grad Dip Biota Instr. Senior RespiratoryScientist, Austin and Repatriation Medical Centre, StudleyRoad, Heidelberg Victoria 3084, Australia. Correspondence to." Dr Morris S. Odell in order that such defences could be evaluated in the light of formal respiratory function testing. Two instruments are used by Victoria Police for conducting breath tests: the Lion Alcolmeter SD2, a portable hand-held device used for screening tests, and the Drager Alcotest 7110 (Drager Australia, 3 Ferntree Place, Notting Hill 3168, Victoria, Australia), which is a precision instrument used to provide evidentiary print-outs accepted by the courts. The Drager Alcotest 7110 which has been used in Victoria since 1994, is specifically defined under the Road Safety Act 1986' and is a substantially different instrument to one with the same name used in other jurisdictions. 2Each of the two instruments under eval- uation contains sensors and circuitry for the purpose of determining when an adequate breath sample has been provided for analysis and will not produce a reading unless pre-set internal criteria have been satisfied. The Lion Alcolmeter uses a simple timer to define the sampling interval. The timer is started once the breath flow exceeds a trigger level and runs for 2.7 s. There is no defined criterion for flow rate during the delay period other than to ensure that the dynamic pressure generated by provision of the sample exceeds the trigger level. Flow/pressure characteristics are defined by disposable plastic tubular mouthpieces, which are mass produced and have a high degree of reproducibility. 45