The Effect of Postural Changes on Spirometric Indices of Upper Airway Obstruction
Kerbala Journal of Medicine,
2013, Volume 6, Issue 2, Pages 1608-1614
Abstractthe spirometric diagnosis of upper airway obstruction is an important non-invasive
technique that was validated for the diagnosis of such lesions relying on several
indices that were derived from the flow volume loops of patients.
Objectives: Is to find out if postural changes have an effect on spirometric indices of airway
obstruction in healthy subjects and if so, does this merit performing the test in supine
Subjects and methods: This study conducted in the department of physiology and medical
physics/ Kerbala medical college, in which 17 males aged from 18-19 years (18.53 ± 0.51),
had BMI of (22.95 ± 2.11 Kg/M2 ), heights of (1.75 ± 0.14 meters) and weights of (70.32 ±
6.34 Kgs) were enrolled. The following spirometric data were measured in two different body
positions (erect versus supine): Forced vital capacity (FVC), Forced inspiratory flow at 50%
of vital capacity (FIF50%), Forced expiratory flow at 50% of vital capacity (FEF50%), Forced
expiratory volume in first second (FEV1), Forced expiratory volume in first 0.5 second (FEV
0.5), Peak inspiratory flow (PIF) and Peak expiratory flow (PEF). From these data, the
following indices of upper airway obstruction were derived: (FEV1/ FEV0.5, FEV1/ PEF,
FEF50%/ FIF50%, and PEF/PIF). These indices were compared with each other in respect to
two body positions.
1- All the measured inspiratory and expiratory flow rates were significantly lower in supine
position (p < 0.05).
2- Of the four measured indices of upper airway obstruction, only the FEV1/PEF ratio
increased significantly (p < 0.05) by about 27% upon reclining.
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