TY - JOUR T1 - The Value of Measuring Inspiratory Capacity in Subjects With Cystic Fibrosis JF - Respiratory Care SP - 981 LP - 987 DO - 10.4187/respcare.05920 VL - 63 IS - 8 AU - Daphna Vilozni AU - Adi Dagan AU - Moran Lavie AU - Ifat Sarouk AU - Bat-El Bar-Aluma AU - Moshe Ashkenazi AU - Sarina Levy Mendelovich AU - Yael Betzalel AU - Ori Efrati Y1 - 2018/08/01 UR - http://rc.rcjournal.com/content/63/8/981.abstract N2 - BACKGROUND: Inspiratory capacity (IC) is often overlooked as an important measured index of spirometry in patients with cystic fibrosis (CF). Abnormally low IC may indicate the onset of static/dynamic hyperinflation, which may be accompanied by dyspnea and an increase in the work of breathing. This cross-sectional study sought to determine whether measuring IC during spirometry, may add clinical value to FEV1 measurements in CF subjects.METHODS: Anthropometric, clinical, spirometry, and static lung volume data were gathered retrospectively from 98 of 165 subjects with CF (mean ± SD age 26.8 ± 11.0 y) registered in The Edmond and Lily Safra Children's Hospital, Sheba Medical Centre, Israel. We compared the IC (% predicted) to FEV1, static lung volumes, and hospitalization days/year.RESULTS: IC decreased alongside FEV1 decline but at a slower pace (r2 = 0.32). Incremental trapped air, as measured by residual volume (RV), and a rapid elevation in the ratio of RV to total lung capacity occurred when IC deteriorated below 60% predicted values. The unique combination of IC < 50% predicted and FEV1 > 40% predicted induced an increase of up to 125 hospitalization days/year compared to subjects having IC > 50% predicted (up to 73 d/y, P < .001).CONCLUSIONS: Measuring IC in CF subjects may reveal silent worsening of lung function as indicated by a decline in IC < 50% predicted while FEV1 is still > 40% predicted. This condition may lead to inefficient breathing at high lung volumes, which may explain a subjective sensation of breathlessness and lead to an increase in hospitalization days/year. ER -