Influence of intercostal muscles contraction on sonographic evaluation of lung sliding: a physiological study on healthy subjects

To investigate the following: (a) effects of intercostal muscle contraction on sonographic assessment of lung sliding and (b) inter-rater and intra-observer agreement on sonographic detection of lung sliding and lung pulse. We used Valsalva and Muller maneuvers as experimental models in which closed glottis and clipped nose prevent air from entering the lungs, despite sustained intercostal muscles contraction. Twenty-one healthy volunteers underwent bilateral lung ultrasound during tidal breathing, apnea, hyperventilation, and Muller and Valsalva maneuvers. The same expert recorded 420 B-mode clips and 420 M-mode images, independently evaluated for the presence or absence of lung sliding and lung pulse by three raters unaware of the respiratory activity corresponding to each imaging. During Muller and Valsalva maneuvers, lung sliding was certainly recognized in up to 73.0