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A comparison between the isovolume and the end‐inflation occlusion methods for measurement of lung mechanics in rats
Author(s) -
Cardoso Wellington Veras,
Saldiva Paulo Hilário Nascimento,
Martins Patricia,
Criado Pereira,
Sakae Regina Silvia,
Böhm György Miklós,
Zin Walter Araújo
Publication year - 1991
Publication title -
journal of applied toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.784
H-Index - 87
eISSN - 1099-1263
pISSN - 0260-437X
DOI - 10.1002/jat.2550110202
Subject(s) - medicine , parenchyma , lung , airway resistance , anatomy , pathology
The isovolume method is one of the most used techniques to assess the mechanical properties of the lungs in ordinary challenge tests and in toxicological studies. It has been considered that isovolume lung resistance ( R L ) could assess central airway calibre in such tests, whereas dynamic elastance ( E L,dyn ) would reflect the elastic properties of lung parenchyma. However, peripheral phenomena, such as Pendelluft and stress relaxation, can interfere with R L measurements, especially in disease. In order to investigate the contribution of such phenomena to isovolume R L and E L,dyn , we compared the results provided by isovolume technique with those given by the end‐inflation occlusion method (EIOM) in 12 normal Wistar rats. We found similar values for total lung resistance ( R L,max ) and isovolume R L . Homogeneous resistance ( R L,min ), which describes airway calibre, comprised about 30% of R L in the tidal volume range. Values of E L,dyn calculated by the EIOM were approximately 20% greater than the corresponding value measured during spontaneous breathing. Our data indicate that isovolume R L is significantly affected by tissue forces and cannot be interpreted as a pure index of airway size.