Spirometry is a simple way to measure functional volumes of lungs. Spirometry determines vital capacity (VC), forced vital capacity (FVC, that reflects the volume of air that undergoes gas exchange), forced expiratory volume per 1 minute (FEV1) and Tiffnaud index, which reflects the ratio between FEV1 and VC. Spirometry also determines estimates that characterize permeability of bronchial tree. Depending upon ratios of these estimates, spirometry diagnoses obstructive lung disease (bronchial narrowing which tales place in bronchial asthma, or chronic obstructive pulmonary disease, for instance, in smokers) or restrictive lung disease (if respiratory muscles function is impaired or cardiac failure is present). Mixed type of dysfunction may also take place. If bronchial narrowing is present, a doctor has to perform a test with a bronchodialtator. That will allow to determine sensitivity to bronchodilatator. Sometimes restrictive and obstructive disorders coincide – for instance, COPD and ALS. In this case bronchodilatation test will allow to determine the true FVC and to prescribe non-invasive ventilation in time. Let uis adduce some Figures of different types of pulmonary dysfunction.