| 摘要 |
A double cuff for endotracheal tubes is designed with two inflatable balloons, shaped to fully occupy the spaces above and below the open larynx. The two cuffs have a common inflation channel and therefore after their inflation are in free communication with each other. The lower cuff with its thin non-elastic walls rests in the upper trachea, applying a pressure against the walls of the upper trachea and subglottic structures determined by the behavior of an upper cuff whose walls are elastic. This elastic cuff occupies the space immediately above the larynx and extends slightly into the pharynx. Elastic properties of the upper cuff confer, in effect, a pressure relief system to the lower non-elastic cuff as a result of their interconnection through the common inflation channel. A short segment of uncuffed tube between the cuffs allows correct anatomical placement of this segment at the level of the larynx, insuring that the inelastic lower cuff rests below the larynx and the elastic upper cuff above the larynx. The proximity of the two cuffs results in an anchor effect around the glottic structures. Maintenance of a seal at low intra-cuff pressures in the trachea and larynx eliminates ciliary injury despite relatively high lung-inflating pressure because the latter is intermittently transmitted into the lower cuff which in turn is pressed against the subglottic structures to provide a satisfactory non-leaking seal for ventilation. Simultaneously the cuffs protect the larynx and trachea from aspiration of secretions from the upper airway into the lung and anchor the tube to prevent both bronchial intubation and inadvertent extubation. |
