Inspiratory muscle strength (IMS) ranges from below normal to supernormal levels in adults with cystic fibrosis (CF). An understanding of disease-related factors contributing to this variability may identify adults with CF at greater risk of respiratory pump dysfunction. The purpose of this study was to explore the ability of clinical measures to predict IMS in adults with CF.Methods:
Maximal inspiratory pressure (MIP) was assessed in 58 adults with stable CF across a range of disease severity (forced expiratory volume in 1-second [FEV1] = 20% to 130% of the predicted) using a cross-sectional design. The ability of clinical factors to predict IMS was evaluated through multivariable regression analysis.Results:
The linear combination of percent of predicted FEV1, percent of predicted residual volume (%RV), lean body mass index, and age explained 43% of the variance in MIP expressed in cm H2O. The linear combination of percent of predicted inspiratory capacity, %RV, and body mass index explained 52% of the variance in MIP expressed as percent of the predicted.Conclusions:
A combination of pulmonary, nutritional, and demographic clinical factors explained approximately half of the variance in IMS in adults with CF. Nutritional status and hyperinflation seem to have the greatest influence on the inspiratory muscles.