Whole body plethysmography

Abstract

After a fundamental explanation of the technical structure and the functioning of whole body plethysmography, attention is called to the fact that this simple method can be performed repeatedly in a minimum of time. Body plethysmography covers the total intrathoracic gas volume, whereas the functional residual capacity determined by means of foreign gas admixture methods covers only the ventilated parts of the lung. The resistance and the pressure flow diagram, enables a differentiation and quantification between absent or present obstructions of the respiratory passages. Comparative studies of the forced expiration test and the resistance show that a linear fall of the spirographic measuring values is accompanied by an exponential rise of the plethysmographic values. Again, the different result of the 2 measuring values may promote the functional analysis of a bronchial asthma or of those diseases associated with a tracheal or bronchial collapse. The influence of single or combined administration of drugs on the bronchi and bronchioles and on the tonus of the bronchial musculature of patients with a chronic obstructive lung disease, can be tested by means of the bronchial flow resistance and the occlusion pressure curve. It is possible to verify a possibly existing, occasionally occupational, bronchomotor hyperreactivity with the help of the acetylcholine test. On the other hand, the isoprenaline test is of value in the differential diagnostic demarcation of permanent from reversible obstructive functional disturbances. It is also advantageous that the bronchial flow resistance can be determined in serial examinations in workers who are in contact with suspected or known respiratory noxae, in order to recognize incipient affections of the respiratory tract. Whole body plethysmography is therefore a highly informative lung function test.