lung conditions are treated by implanting a flow restrictor in a passageway upstream from a diseased lung segment . the restrictor will create an orifice at the implantation site which inhibits air exchange with the segment to induce controlled atelectasis and / or hypoxia . controlled atelectasis can induce collapse of the diseased segment with a reduced risk of pneumothorax . hypoxia can promote gas exchange with non - isolated , healthy regions of the lung even in the absence of lung collapse .