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Authors of a prospective, observational study published in Respiratory Medicine found a link between diaphragm dysfunction and poor asthma control with longer disease duration. Andrea Portacci and colleagues evaluated diaphragm function in 50 patients with asthma and 50 healthy controls. The researchers used tidal breathing thickening fraction (TF) to assess diaphragmatic contraction, with diaphragm dysfunction defined as TF less than 20%. Additional assessments included spirometry, impulse oscillometry, FeNO, blood eosinophil count, and the Sniff Inspiratory Nasal Pressure (SNIP) test. Patients with asthma exhibited significantly lower diaphragm TF compared with healthy controls (P<0.001), with dysfunction affecting 62% to 66% of the right hemidiaphragm and 46% to 54% of the left. Lower TF was associated with longer disease duration (P=0.03) and higher exacerbation rates (P=0.04) but showed no correlation with lung function, Th2 biomarkers, or asthma treatments. SNIP measurements did not correlate with TF. Study limitations included a small sample size and cross-sectional design. The researchers concluded that diaphragm function may be a treatable trait in asthma, contributing to persistent symptoms and exercise intolerance.