Goal is to physiologically detect unsuspected small airways obstruction in children and adults with treated heterozygous and homozygous cystic fibrosis. Unsuspected refers to normal routine pre bronchodilator spirometry including normal FEV1(L), FVC (L). and FEV1/FVC%. This is a retrospective study.

The current study is based on current investigators previously published patho-physiologic and lung CT studies in small airways intrinsic obstruction, emphysema, and asthma. Current investigators have demonstrated that despite the presence of normal routine spirometry including normal FEV1(L), FVC (L), and FEV1/FVC% that unsuspected small airways obstruction, and emphysema can be detected. This has been achieved by presence of isolated abnormal expiratory airflow limitation at low lung volumes on the maximal expiratory flow volume curves. This includes abnormal expiratory airflow at 75% and 80% expired lung volume. Current investigators believe investigators will be able to detect unsuspected small airways intrinsic obstruction, and peripheral airway bronchiectasis proven by lung CT, in patients with cystic fibrosis despite presence of pre bronchodilator normal routine spirometry.

Inclusion Criteria:

Heterozygote or homozygote patients with cystic fibrosis with normal routine pre bronchodilator spirometry including normal FEV1(L), FVC(L) and FEV1/FVC%.

Exclusion Criteria:Heterozygote or homozygote patients with cystic fibrosis with ABNORMAL routine pre bronchodilator spirometry

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Review pulmonary function and radiologic studies in retrospective records of heterozygote or homozygote patients with cystic fibrosis

All individual published data will be shared

when published

published data