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Forced midexpiratory time: reference values and the effect of cigarette smoking
L K Brown1, A Miller, M Pilipski
1Department of Medicine, Mount Sinai Medical Center, New York, NY, 10029, USA.
Lung
|January 1, 1995
Summary
Forced midexpiratory time (FET25-75%) is a useful measure of airway obstruction. Age is the primary factor influencing FET25-75% values, with simplified reference values recommended.
Area of Science:
- Pulmonary function testing
- Respiratory physiology
Background:
- Forced midexpiratory time (FET25-75%) is considered a volume-independent measure of airflow obstruction.
- Previous studies have not systematically evaluated factors like age, height, sex, and smoking history on normal FET25-75% values.
Purpose of the Study:
- To systematically investigate the influence of age, height, sex, and smoking history on normal FET25-75% values.
- To establish reliable reference equations for FET25-75%.
Main Methods:
- Analysis of flow-volume loops from 369 normal lifetime nonsmokers and smokers.
- Application of linear models incorporating age and height, with and without logarithmic transformations.
Main Results:
- Age and height had a minimal impact on FET25-75% variability compared to other spirometric measures.
- Male smokers showed the highest R-squared values, with age being the most significant contributor, indicating a potential smoking effect.
- The best predictive models utilized age, or age and height, without data transformation.
Conclusions:
- Age is the primary determinant of FET25-75% values, although its contribution to variability is small.
- Simplified, age-stratified reference values for FET25-75% are proposed based on the study's findings.