Selection of variables from maximum expiratory flow-volume curves

Area of Science:

• Pulmonary Physiology
• Pediatric Respiratory Medicine

Background:

• Standardized methods for analyzing maximum expiratory flow-volume curves are crucial for accurate physiological variable estimation.
• Existing methods, often recommended for adults, require evaluation for adolescent populations.

Purpose of the Study:

• To compare the performance of eight different methods for estimating physiological variables from maximum expiratory flow-volume curves in adolescents aged 12-16 years.
• To determine the optimal number of acceptable curves for reliable pulmonary function testing in this demographic.

Main Methods:

• A comparative analysis of eight distinct methods was conducted on data from 433 adolescents.
• Measurements included forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1), along with expiratory flows.
• Reproducibility was assessed using within-individual coefficients of variation, comparing 3 versus 5 acceptable curves.

Main Results:

• Mean values for FVC and FEV1 differed by less than 6% across methods compared to the ATS-recommended method, with larger discrepancies for MEF25.
• Within-individual coefficients of variation for FVC and FEV1 showed no significant difference between methods and improved with 5 acceptable curves.
• Expiratory flow variability ranged from 4.2% to 9.4%, with inconsistent improvements when using more than 3 acceptable curves.

Conclusions:

• For adolescents, using more than three acceptable expiratory maneuvers is not cost-effective for pulmonary function testing.
• The envelope method and a maximum composite curve derived from FVC reproducible within 5% are recommended for use with teenagers.