Isolated abnormal FEF75% detects unsuspected bronchiolar obstruction in CF children

Area of Science:

• Pediatric Pulmonology
• Respiratory Medicine
• Cystic Fibrosis Research

Background:

• Physiologic detection of bronchiolar obstruction in children with cystic fibrosis (CF) can be challenging due to normal spirometry despite CT-confirmed bronchiectasis.
• Small airways obstruction in CF may go clinically unsuspected.

Purpose of the Study:

• To investigate the utility of specific spirometric measures, particularly FEF75%, in detecting early and isolated small airways obstruction in children with CF.
• To assess if FEF75% can identify subclinical airway disease in CF patients with normal routine spirometry.

Main Methods:

• Retrospective analysis of spirometry data from children at two CF facilities over 16 years.
• Focus on pre-bronchodilator maximum expiratory flow volume curves to identify abnormal FEF75% despite normal routine spirometry.
• Data collected every 3 months during clinically stable periods.

Main Results:

• An abnormal FEF75% was detected in 26 CF children at a mean age of 7.5 years, persisting as an isolated abnormality for 2.5 years.
• At another center, abnormal FEF75% occurred in 13 children (mean age 11.7 years), and abnormal FEF25-75% in 10 (mean age 11.8 years), despite initially normal spirometry.
• FEF75% proved to be the most sensitive test for diagnosing early and isolated progressive bronchiolar obstruction.

Conclusions:

• FEF75% is a sensitive spirometric marker for detecting unsuspected small airways obstruction in children with CF.
• This test can identify subclinical disease in CF patients with normal routine spirometry and bronchiectasis, allowing for optimized targeted therapies.