HRR1 correlated significantly with FVC, FEV1, FEV1% pred, FEV1/FVC (%), FEF50, FEF50%, FEF75, FEF75%, and DLco.
What is interesting here is that the small airway obstruction along with the DLco was more deranged in HRR < 16 group of patients that is, FEF50, FEF50% FEF75, FEF75%, DLco (% pred) (P < 0.05) (Table 3).
Scientists observed that long term tobacco smoking has resulted in decline in parameters of pulmonary functions and reported significantly abnormal values of [FEV.sub.1], FVC, PEFR and FEF50
among chronic smokers.
In the study of Ren et al., the pulmonary function parameters including, FVC, FEV1, FEV1/FVC, PEFR, FEF25, FEF50
, decreased significantly with age in both male and female subjects.
Evidence of obstruction within the middle and small airways of the lungs is suggested by low values of the forced expiratory flows (FEF25, FEF50, FEF75, or FEF25-75).
 The obstruction could be within the middle and the small airways, as indicated by the low values of the forced expiratory flows (FEF25, FEF50, FEF75, and FEF25-75).
2004 FVC (% predicted) 98.1 [+ or -] 109.9 [+ or 0.005 15.0 -] 22.0 FEV[V.sub.1] (% 98.1 [+ or -] 108.5 [+ or 0.008 predicted) 14.0 -] 21.0 PEF (% predicted) 116.1 [+ or -] 115.2 [+ or 0.8 18.0 -] 22.0 FEF25 (% 105.2 [+ or -] 104.7 [+ or 0.9 predicted) 21.0 -] 17.0 FEF50
(% 87.4 [+ or -] 89.8 [+ or 0.5 predicted) 22.0 -] 20.0 FEF75 (% 73.1 [+ or -] 82.7 [+ or 0.06 predicted) 24.0 -] 28.0 Abbreviations: FEF25, 50, 75, forced expiratory flow 25%, 50%, 75% of FVC; PEF, peak expiratory flow.
Post-bronchodilator FVC, FEV1, peak expiratory flow rates (PEF), FEF50
and skinprick tests were measured at age 12.