Lung function test (LFT) is a good picture of how much air moves in and out of lung and how efficiently oxygen is moved in and carbon dioxide is moved out. The published guidelines for measuring PEF by American thoracic society provide no precise recommendations about the speed of inspiration preceding expiration and the appropriate duration of the post inspiratory pause. Although long post inspiratory pauses (> 3s) are generally not used, pauses of 3s). Whereas according to American thoracic society, pause of ...