Descriptive study of the use of ultrasound in the assessment of diaphragmatic dysfunction

Diaphragmatic dysfunction is a pathology that affects the mobility of the diaphragm and its etiology can be due to multiple causes. The assessment requires combining numerous tools for diagnosis. Ultrasound (US) is a non-invasive and accessible technique in most respiratory units and allows a direct objective assessment of the diaphragm. The main objective of the study was to evaluate the diagnostic yield of US in suspicion of diaphragmatic dysfunction previously evidenced by complementary indirect tests and assess the possible limitations of the technique. A retrospective descriptive study was carried out in 20 patients with suspected diaphragmatic dysfunction due to finding of hemidiaphragm elevation or due to functional study of hypoventilation (October 2022-October 2023). Patient data is shown in figure 1. Diaphragmatic mobility was measured in volume tidal and deep breathing, using convex probe in M mode, and the shortening fraction using linear probe in mode B, in patient in supine position at 45º. Shortening fraction was calculated and reference values were used (A Boussuges et al, CHEST 2009; 135:391-400). US detected 25% of paresis and 30% of paralysis (figure 2), predominantly unilateral (90%) and right (55%). Left hemidiaphragm mobility in supine position could not be measured in 25%. In patients referred for radiological finding ultrasound has shown: S 58%, E 100%, PPV 100%, NPV 30% (p<0.06) with a significant LR (p<0.03). US has a reasonable diagnostic yield when diaphragmatic dysfunction is suspected. The most important limitation occurs in the assessment of left hemidiaphragmatic mobility in supine position. Further research is needed to generalize the technique and normal values.