抄録
We analyzed the pleural surface pressure by use of a lung-thorax model under static conditions.
The lung-thorax model consists of a balloon covered by a net, hung inside a box. The balloon connects to the outside atmosphere. When pressure in the box is lowered by suction of air, the balloon expands inside it. When the pressure difference between inside the box and inside the balloon exceeds the elastic recoil pressure of the balloon, the balloon surface contacts the net and the mechanical forces, i. e., the contact pressure act on the balloon surface. Therefore the intra-balloon pressure is equal to the sum of the elastic recoil pressure of the balloon, the intra-box pressure and the contact pressure between the balloon and the net. It was shown that pleural contact pressure which varies inversely with pulmonary elastic recoil pressure, i. e., pleural surface pressure, is an important force in the interaction between lung and chest wall.
In the chest cavity in cases of lobar atelectasis, the pleural surface pressure of the chest wall and adjacent expanded lobes increase. Consequently the pleural contact pressure surrounding the atelectatic lobe decreases. Then the mechanical relationship works to increase pleural contact pressure, thereby working against atelectasis. The more extensive the lobar atelectasis the more the contact pressure decreases, therefore mechanical forces against atelectasis work more strongly.
