Effect of inspired volume on airway closure in relation to age
Holtz, B.; Bake, B.; Winstedt, P.
Scandinavian Journal of Respiratory Diseases 60(3): 119-127
1979
ISSN/ISBN: 0036-5572 PMID: 493901 Document Number: 149778
Closing volume (CV) was measured in 64 healthy subjects aged 18-76 yr in supine position with a bolus (He) technique in 2 ways: following a maximal (CV100) and a submaximal (= 50% VC = 0.46, P < 0.001), e.g., at 70 yr of age CV100 = 32 (%VC) and CV50 = 24 (%VC). During normal breathing elderly subjects do not presumably close airways at as high a lung volume as predicted from conventional CV measurements. A strong correlation between CV50 and CV100 was found, CV50 (%VC) = 0.55 .times. CV100 (%VC) + 5.3 (r = 0.90; P < 0.001), allowing a more accurate prediction of CV50 from CV100 than from age. Neither smoking habits nor body position affected the decrease of CV with reduced inspired volume.