Ultrasound M-mode assessment of diaphragmatic kinetics by anterior transverse scanning in healthy subjects.

The purpose of this study was to set an effective standardized method to assess diaphragmatic kinetics by ultrasound. Forty healthy volunteers were submitted to a B- and M-mode ultrasound study using a convex transducer positioned in the subcostal anterior area for transverse scanning. Ultrasound examination was completed in 38/40 cases (95%), spending on average <10 min for examination. The resting and forced diaphragmatic excursions were 18.4 ± 7.6 and 78.8 ± 13.3 mm, respectively, unrelated to demographic or anthropometric parameters: intraobserver variability on three successive measurements resulted in 6.0% and in 3.9%, respectively. An inexperienced sonographer completed the ultrasound examination in 37/40 cases, spending on average >15 min, with significant, although marginal, interobserver variability (31.9% and 14.7% for resting and forced diaphragmatic excursion, respectively). Bedside ultrasonography by an anterior subcostal transverse scanning on semi-recumbent patient proves to be a safe, feasible, reliable, fast, relatively easy and reproducible way to assess diaphragm movement.