COMPUTER-ASSISTED RECOGNITION AND QUANTITATION OF THE EFFECTS OF AIRBORNE CHEMICALS ACTING AT DIFFERENT AREAS OF THE RESPIRATORY-TRACT IN MICE

The pattern and timing of a normal breath in unanesthetized mice was a nalyzed from measurement of inspiratory and expiratory airflows (VI an d VE). Airflow was measured via a differential pressure transducer, at tached to a pneumotachograph, which itself was attached to a body plet hysmograph into which a mouse was placed. The analog voltage from the differential pressure transducer was digitized and stored for analysis on a microcomputer. Criteria were developed to classify each breath a s normal (N) or belonging into one of seven abnormal categories. The a bnormal categories were arrived at by computer analysis, recognizing s pecific modifications of the normal pattern into patterns of: sensory irritation of the upper respiratory tract (S), airflow limitation with in the conducting airways of the lungs (A) or pulmonary irritation at the alveolar level (P). Combinations of these effects, i.e., S+A, P+A, P+S and P+S+A were also recognized. Computer analysis of each breath also permitted quantitative evaluation of the degree of S, A or P abno rmalities. To induce each type of effect we used inhalation exposures to 2-chlorobenzylchloride, carbamylcholine or propranolol. We propose that this approach will permit rapid evaluation of the possible effect s of airborne chemicals at three levels of the respiratory tract, with the classification of the type of effect easily obtained in an object ive way using well defined criteria, followed by quantitation of the d egree of each effect.