Effect of body posture on dynamic lung functions in young non-obese Indian subjects.

Flow volume loop and its various indices can be used to diagnose UAO. Change in posture from sitting to horizontal position per se causes a decrease in effort dependent inspiratory and expiratory flow rates but no significant change in upper airway obstruction indices. Thus, measurement of FVL in supine posture may be used to detect UAO as it may be missed if spirometry is performed in sitting posture.