Sonographic measurement of diaphragmatic displacement during tidal breathing manoeuvres - a reliability study.

The aim of this investigation was to establish a reliable method of measuring diaphragm movement during relaxed tidal breathing. This study follows a previous study in which test-retest reliability was established for maximal breaths but not for tidal breaths (Blaney and Sawyer 1997). Twelve normal subjects were tested in a semi-reclined long sitting position. Sonographic measurements were taken for tidal breaths during four different patterns of breathing. All breaths were controlled for inspired volume. Testing was repeated one week later under the same conditions. The results showed that the method for measuring diaphragmatic movement at tidal breathing during a given pattern of breathing was reliable. This method will allow further investigation of the diaphragm during different breathing manoeuvres at tidal volume.