A cuff type indwelling device such as a tracheal tube, catheter or the like is provided with a cuff balloon and a pilot balloon of full volume non-stretchable, non-resilient flexible material, and means for inflating both balloons. The pilot balloon is of generally spherical shape when expanded and is...http://www.google.com.hk/patents/US4552558?utm_source=gb-gplus-share專利 US4552558 - Pressure warning, indicating and applying monitor for cuff type indwelling devices
