Change in forced expiratory time and spirometric performance during a single pulmonary function testing session

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology

Background:

• Clinical improvement and bronchodilator response in obstructive lung disease often show poor correlation.
• Forced expiratory time (FET) is a potential factor explaining this discrepancy but has been understudied.

Purpose of the Study:

• To analyze changes in FET during spirometry in patients with and without airflow obstruction.
• To evaluate the relationship between FET and spirometric performance.
• To assess the effect of bronchodilators on FET in patients with airflow obstruction.

Main Methods:

• Analysis of FET changes during the first three satisfactory flow-volume loops in 102 patients (37 normal, 65 with airflow obstruction).
• Inclusion of both PFT-naïve and PFT-experienced individuals.
• Evaluation of FET's association with spirometric performance and bronchodilator response.

Main Results:

• Significant increases in FET and spirometric performance were observed during initial spirometry attempts in both normal and obstructed groups (p < 0.001).
• Increments in FET were significantly associated with improved spirometric performance across all subgroups.
• Bronchodilator administration led to a modest FET increment in patients with airflow obstruction (p = 0.009), but did not differentiate responders from non-responders.

Conclusions:

• Patients with normal pulmonary function and those with obstruction exhibit increasing FET during initial spirometry, irrespective of prior PFT experience.
• Longer FET is linked to enhanced spirometric performance.
• While bronchodilators modestly prolong FET, FET changes are not predictive of bronchodilator response.