Breath testing in patients with respiratory disability.

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.