TY - JOUR
T1 - Effect of asbestos-related pleural fibrosis on excursion of the lower chest wall and diaphragm
AU - Singh, Bhajan
AU - Eastwood, Peter R.
AU - Finucane, Kevin E.
AU - Panizza, Janine A.
AU - Musk, Arthur W.
N1 - Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1999/11
Y1 - 1999/11
N2 - To examine mechanisms responsible for reduced lung volumes (restriction) in asbestos-related pleural fibrosis (APF), we studied diaphragm function and lower rib-cage excursion in 26 subjects with previous asbestos exposure and no evidence of asbestosis. Using posteroanterior (PA) and lateral chest radiographs taken at residual volume and at 25%, 70%, and 100% vital capacity (VC) during a slow inspiratory maneuver, we measured fractional expansion of the lower rib cage (FErc), fractional shortening of the diaphragm (FSdi), and changes (Δ) in diaphragm dome height (Hdo) and subphrenic volume (Vdi). Vdi was estimated by measuring the major and minor axes of the subphrenic space at 1-cm intervals, assuming an elliptical cross-sectional shape, and correcting for the volume of spinal and paraspinal tissues. Seven subjects had no evidence of APF (control), 12 had pleural plaques (PP), and seven had diffuse pleural thickening with costophrenic obliteration (DPT). Over the range of VC, results (mean ± SFM, normalized for height) in control subjects were VC = 101.2 ± 4.0 % predicted and ΔVdi = 326 ± 8 ml/m3, and for the right hemithorax and hemidiaphragm on the PA film, FErc = 0.07 ± 0.02, FSdi = 0.32 ± 0.02 and ΔHdo = 0.8 ± 0.2 cm/m. Relative to controls: DPT subjects had reduced VC (77.4 ± 4.9%, p < 0.01), ΔVdi (256 ± 2 ml/m3, p < 0.01), FErc (0.01 ± 0.02, p < 0.01), FSdi (0.24 ± 0.01, p < 0.001), and ΔHdo (-0.9 ± 0.06 cm/m, p < 0.01); PP subjects had reduced FSdi (0.25 ± 0.01, p < 0.001) and ΔVdi (233 ± 47 ml/m3, p < 0.01), and no difference in FErc, ΔHdo, or VC. We conclude that restriction in DPT is due to obliteration of the zone of apposition, and that by limiting separation of the diaphragm from the rib cage during inspiration, this reduces volume contributed by motion of the diaphragm and lower rib cage. Reduction in the latter contribution was the main cause of restriction, because the reduction in volume contributed by the diaphragm was partly compensated by flattening of its dome.
AB - To examine mechanisms responsible for reduced lung volumes (restriction) in asbestos-related pleural fibrosis (APF), we studied diaphragm function and lower rib-cage excursion in 26 subjects with previous asbestos exposure and no evidence of asbestosis. Using posteroanterior (PA) and lateral chest radiographs taken at residual volume and at 25%, 70%, and 100% vital capacity (VC) during a slow inspiratory maneuver, we measured fractional expansion of the lower rib cage (FErc), fractional shortening of the diaphragm (FSdi), and changes (Δ) in diaphragm dome height (Hdo) and subphrenic volume (Vdi). Vdi was estimated by measuring the major and minor axes of the subphrenic space at 1-cm intervals, assuming an elliptical cross-sectional shape, and correcting for the volume of spinal and paraspinal tissues. Seven subjects had no evidence of APF (control), 12 had pleural plaques (PP), and seven had diffuse pleural thickening with costophrenic obliteration (DPT). Over the range of VC, results (mean ± SFM, normalized for height) in control subjects were VC = 101.2 ± 4.0 % predicted and ΔVdi = 326 ± 8 ml/m3, and for the right hemithorax and hemidiaphragm on the PA film, FErc = 0.07 ± 0.02, FSdi = 0.32 ± 0.02 and ΔHdo = 0.8 ± 0.2 cm/m. Relative to controls: DPT subjects had reduced VC (77.4 ± 4.9%, p < 0.01), ΔVdi (256 ± 2 ml/m3, p < 0.01), FErc (0.01 ± 0.02, p < 0.01), FSdi (0.24 ± 0.01, p < 0.001), and ΔHdo (-0.9 ± 0.06 cm/m, p < 0.01); PP subjects had reduced FSdi (0.25 ± 0.01, p < 0.001) and ΔVdi (233 ± 47 ml/m3, p < 0.01), and no difference in FErc, ΔHdo, or VC. We conclude that restriction in DPT is due to obliteration of the zone of apposition, and that by limiting separation of the diaphragm from the rib cage during inspiration, this reduces volume contributed by motion of the diaphragm and lower rib cage. Reduction in the latter contribution was the main cause of restriction, because the reduction in volume contributed by the diaphragm was partly compensated by flattening of its dome.
UR - http://www.scopus.com/inward/record.url?scp=0032742789&partnerID=8YFLogxK
U2 - 10.1164/ajrccm.160.5.9806135
DO - 10.1164/ajrccm.160.5.9806135
M3 - Article
C2 - 10556113
AN - SCOPUS:0032742789
VL - 160
SP - 1507
EP - 1515
JO - American Journal of Respiratory and Critical Care Medicine
JF - American Journal of Respiratory and Critical Care Medicine
SN - 1073-449X
IS - 5
ER -