[Study of peak expiratory flow in normal young, middle-aged and old persons in Chengdu area].

Objective: To build the normal ranges and regression equations of peak expiratory flow (PEF) in normal young, middle-aged and old persons.

Methods: PEF, FVC, V75, V50, V25 were measured in 393 normal young, middle-aged and old persons with the youngest aged 20 years and the eldest 84 years. Regression equations of PEF were built for younger group (20 yr-49 yr) and elder group (50 yr-84 yr) respectively.

Results: PEF, FVC, V75, V50, V25 were decreased with increase of age. The regression equations showed that both in younger and elder groups, PEF was negatively correlated with age in male (P < 0.0001-0.002, r = 0.32-0.39) and positively correlated with FVC in female (P < 0.0001-0.0005, r = 0.32-0.59). PEF was highly correlated to V75 with r = 0.87-0.94 in male and r = 0.93-0.96 in female. The coefficient of variation (CV) of PEF was in normal range (16%-24%) for all age groups except male and female above 70 years old with CV of 30% and 27% respectively. This confirmed the data was reliable.

Conclusion: The normal ranges and regression equations of PEF constructed as a result of this study for normal humans of 20-84 years old can be put to use in clinical work and public health.