Portex Replacement Fenestrated Inner CannulaPortex Replacement Fenestrated Inner Cannula The Portex Replacement Fenestrated Inner Cannula by Smiths Medical is a thin tube inserted into the Portex D. I. C. Tracheostomy Tube to facilitate patient care and reduce post procedural infection. The Inner Cannula is constructed of a soft, flexible, and lightweight siliconized polyvinyl chloride (PVC) plastic which not only makes for an easy application but it reduces the risk of tracheal trauma. The