[Change in the zone of apposition of the human diaphragm associated with ventilatory movement]

The movement of the cephalic margin of the zone of apposition (ZOA) of the diaphragm associated with ventilatory movement was measured using ultrasonography in 24 healthy subjects and 45 patients with various pulmonary diseases. A transducer was placed on the lower chest wall, and movement of the cephalic margin of ZOA was measured during maximal inspiratory maneuver and expiratory maneuver from end expiratory position in supine and sitting positions in healthy subjects, and in the supine position in patients. In healthy subjects, there was a linear relationship between inspiratory or expiratory volumes and movement of the cephalic margin of ZOA. Movement in the supine position during vital capacity maneuver was 103.0 +/- 15.6 (mean +/- SD), 106.6 +/- 17.2, 108.5 +/- 18.2, and 114.8 +/- 16.3 mm on the left anterior, right anterior, left posterior, and right posterior axillary lines, respectively. In the supine position, movement on the right posterior axillary line was significantly larger than that measured on other axillary lines (p less than 0.05). Movement during maximal inspiratory maneuver in the supine position was significantly larger than that in the sitting position (p less than 0.01). Movement during maximal expiratory maneuver in the supine position was significantly smaller than that in the sitting position (p less than 0.01). Patients showed decreased movement and great differences in movement between the left and right anterior axillary lines. Seven patients out of 28 with normal spirograms showed decreased movement on either or both sides. These data suggest that: 1) the movement of the cephalic margin of ZOA reflects diaphragm displacement; and 2) difference in ventilatory function of right and left hemithorax can be detected by movement of the cephalic margin of ZOA.