Regional Relationship Between Changes of Electrical Impedance and Diameter of the Thorax During Ventilation

抄録

The relationship between the electrical impedance fluctuation (ΔZ) and the chest cage movement(ΔTD) associated with ventilation on either upper and lower zones of the hemithorax or the bilateral sides of the thorax were discussed in the range of the vital capacity which was measured by the conventional spirometry (ΔV) in fifteen normal adults. The ventilatory variation of the impedance in the two regions were smaller at the top and larger at the bottom. The dorso-ventral diameter changes, ΔZ/ΔV and ΔTD/ΔV had a similar tendency. Despite correlatibe change between ΔZ and ΔTD in the normal adults, the impedance fluctuated without evident TD change in the abdominal ventilation, and the chest cage moved without evident impedance change in the area under which thoracoplasty was carried out. These results suggest that the ventilatory impedance variation is evoked not by the chest wall movement but by distribution of the inspired air into the region under the electrode, and the impedance method may detect the regional ventilation evidently.