TY - JOUR
T1 - Preventing mediastinal shift after pneumonectomy does not abolish physiological compensation
AU - Wu, E. Y.
AU - Hsia, C. C W
AU - Estrera, A. S.
AU - Epstein, R. H.
AU - Ramanathan, M.
AU - Johnson, R. L.
PY - 2000/7
Y1 - 2000/7
N2 - To determine the role of mediastinal shift after pneumonectomy (PNX) on compensatory responses, we performed right PNX in adult dogs and replaced the resected lung with a custom- shaped inflatable silicone prosthesis. Prosthesis was inflated (Inf) to prevent mediastinal shift, or deflated (Def), allowing mediastinal shift to occur. Thoracic, lung air, and tissue volumes were measured by computerized tomography scan. Lung diffusing capacities for carbon monoxide (DL(CO)) and its components, membrane diffusing capacity for carbon monoxide (Dm(CO)) and capillary blood volume (Vc), were measured at rest and during exercise by a rebreathing technique. In the Inf group, lung air volume was significantly smaller than in Def group; however, the lung became elongated and expanded by 20% via caudal displacement of the left hemidiaphragm. Consequently, rib cage volume was similar, but total thoracic volume was higher in the Inf group. Extravascular septal tissue volume was not different between groups. At a given pulmonary blood flow, DL(CO) and Dm(CO) were significantly lower in the Inf group, but Vc was similar. In one dog, delayed mediastinal shift occurred 9 mo after PNX; both lung volume and DL(CO) progressively increased over the subsequent 3 mo. We conclude that preventing mediastinal shift after PNX impairs recruitment of diffusing capacity but does not abolish expansion of the remaining lung or the compensatory increase in extravascular septal tissue volume.
AB - To determine the role of mediastinal shift after pneumonectomy (PNX) on compensatory responses, we performed right PNX in adult dogs and replaced the resected lung with a custom- shaped inflatable silicone prosthesis. Prosthesis was inflated (Inf) to prevent mediastinal shift, or deflated (Def), allowing mediastinal shift to occur. Thoracic, lung air, and tissue volumes were measured by computerized tomography scan. Lung diffusing capacities for carbon monoxide (DL(CO)) and its components, membrane diffusing capacity for carbon monoxide (Dm(CO)) and capillary blood volume (Vc), were measured at rest and during exercise by a rebreathing technique. In the Inf group, lung air volume was significantly smaller than in Def group; however, the lung became elongated and expanded by 20% via caudal displacement of the left hemidiaphragm. Consequently, rib cage volume was similar, but total thoracic volume was higher in the Inf group. Extravascular septal tissue volume was not different between groups. At a given pulmonary blood flow, DL(CO) and Dm(CO) were significantly lower in the Inf group, but Vc was similar. In one dog, delayed mediastinal shift occurred 9 mo after PNX; both lung volume and DL(CO) progressively increased over the subsequent 3 mo. We conclude that preventing mediastinal shift after PNX impairs recruitment of diffusing capacity but does not abolish expansion of the remaining lung or the compensatory increase in extravascular septal tissue volume.
KW - Dog
KW - Exercise
KW - Gas exchange
KW - Lung strain
KW - Membrane diffusing capacity
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U2 - 10.1152/jappl.2000.89.1.182
DO - 10.1152/jappl.2000.89.1.182
M3 - Article
C2 - 10904051
AN - SCOPUS:0033913156
SN - 8750-7587
VL - 89
SP - 182
EP - 191
JO - Journal of applied physiology
JF - Journal of applied physiology
IS - 1
ER -