The Effect of Postural Changes on Spirometric Indices of Upper Airway Obstruction


the spirometric diagnosis of upper airway obstruction is an important non-invasivetechnique that was validated for the diagnosis of such lesions relying on severalindices 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 airwayobstruction in healthy subjects and if so, does this merit performing the test in supineposture?Subjects and methods: This study conducted in the department of physiology and medicalphysics/ 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 bodypositions (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%), Forcedexpiratory volume in first second (FEV1), Forced expiratory volume in first 0.5 second (FEV0.5), Peak inspiratory flow (PIF) and Peak expiratory flow (PEF). From these data, thefollowing 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 totwo body positions.Results:1- All the measured inspiratory and expiratory flow rates were significantly lower in supineposition (p < 0.05).2- Of the four measured indices of upper airway obstruction, only the FEV1/PEF ratioincreased significantly (p < 0.05) by about 27% upon reclining.