Leakage of fluid past the tracheal tube cuff in a benchtop model.

We have assessed a range of high volume, low pressure (HVLP) cuffed tracheal tubes in a benchtop model, for leakage of fluid from above the cuff to the model trachea below, during various ventilatory modes. Rapid leakage occurred in the model during all modes of ventilation, unless tracheal pressure was greater than the height of fluid in the column above the cuff. This leakage occurred preferentially down longitudinal folds that occur in the HVLP cuff wall. This model suggests that, if a longitudinal fold within the cuff wall is patent, then the possibility exists of subglottic to tracheal leakage.