Improved respiratory CO2-He analysis for peripheral airways impairment detection. Utilization possibilities of a new computerized system in preventive medicine studies.

The authors illustrate the application possibilities in occupational and preventive medicine of a recently computerized system for the evaluation of peripheral ventilatory non-homogeneities with or without alveolar air trapping. The method consists of an improved individual multiple breath by breath test utilizing the analysis of the respiratory gases CO2 and He. It is based on the results of previous experimental measurements performed simultaneously in different pulmonary sectors an depends on the technical possibility of signalizing out-of-phase expired CO2-He mixtures at the end of the inert gas clearance when in subjects with peripheral respiratory disorders the two gases CO2 and He arrive at the mouth at different times, during the same expiration and cause different, opposite signals. The applied physiological reliability of the measurements was experimentally verified, their technical specificity was recently established. The use of a new computerized system allows actually automatic, on-line measurements under the control of the operator, following a standardized method. The resolution power of the signals is very high. The calculation of the results is performed by the software. The system is easy to transport and can be used in the field for screening on large groups of persons in preventive medicine inquiries and during occupational medicine checks. Quite recently it has been usefully employed during an investigation on 200 subjects, occupationally exposed (policemen of the city traffic department of the town of Bologna).