Quantifying the shape of the maximal expiratory flow-volume curve in mild COPD.
Maximal expiratory flow-volume (MEFV) curve evaluation using absolute and percent predicted values of flow and volume are used to diagnose respiratory disease, but the shape of the curve is rarely used. Three mathematical methods were used to quantify shape of MEFV curves in subjects with mild COPD (n=19) and matched healthy controls (n=15). Those with mild COPD had a significantly greater slope-ratio (SR) (1.90 ± 0.24 vs. 1.28 ± 0.32) and Beta-angle (160 ± 6.7 vs. 186 ± 15.0) compared to healthy individuals (p<0.05). The flow-ratio method showed no difference between groups. A significant positive SR-volume relationship during expiration was observed in a greater number of mild COPD subjects (94%) compared to controls (20%) (p<0.001). With its increased spatial resolution and the potential to discern etiology behind specific curvature, we suggest using the SR method when available. The change in SR throughout expiration could help identify those who fall within the lower limit of normal lung function and those who may have pathological obstruction.
School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. Electronic address: p.dominelli@alumni.ubc.ca.
Paolo B
PB
Dominelli
Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada.
Glen E
GE
Foster
Centre for Heart Lung Innovation and Department of Physical Therapy, University of British Columbia, St. Paul's Hospital, Vancouver, BC, Canada.
Jordan A
JA
Guenette
Johnson State College, Johnson, VT, United States.
Hans C
HC
Haverkamp
Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada.
Neil D
ND
Eves
Division of Respirology, University of British Columbia, Vancouver, BC, Canada.
Giulio S
GS
Dominelli
School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Division of Critical Care Medicine, University of British Columbia, Vancouver, BC, Canada.
William R
WR
Henderson
Respiratory Investigation Unit, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, Ontario, Canada.
Denis E
DE
O'Donnell
School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.
A William
AW
Sheel
D000368:Aged; D005260:Female; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008449:Maximal Expiratory Flow-Volume Curves; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012189:Retrospective Studies
Effort independent; Lung heterogeneity; Pulmonary function; Slope-ratio; Spirometry