Insufficient deflation of a reinforced tracheal tube cuff

We managed a recent case using an 8.0-mm internal diameter reinforced tracheal tube (Hudson RCI® Sheridan Spiral-Flex®, Teleflex Medical, Rüsch GmbH, Kernen, Germany). Following extubation, we noted that the tracheal cuff was still inflated, putting the patient at risk of vocal cord trauma. The anaesthetic assistant had used a 20-ml syringe to deflate the cuff until the pilot balloon appeared to be empty. Ideally, one would accurately record the exact amount of air used for cuff inflation and then aspirate that volume of air before extubation. This may not remain accurate in many instances, for example, if nitrous oxide has been used, and in reality, the volume used is often not recorded, even if a pressure transducer is used to guide cuff inflation. In some cases, the balloon might be topped up during surgery in the event of a perceived ‘cuff leak’. Thus, we use the pilot balloon’s appearance and feel to provide feedback on cuff inflation. Our case suggested that the appearance and feel of our pilot balloon did not relate to the volume in the cuff. We further tested the pilot balloon by measuring the pressures using a cuff pressure gauge (VBM Medizintechnik GmbH, Sulz a.N., Germany) after adding 5, 10, 15 and 20 ml air. The respective pressures were 0, 2, 13 and 46 cmH2O. Although one would not necessarily expect there to be a linear relationship between cuff volume and pressure, we are concerned that the pilot balloon of the Spiral-Flex tube does not begin to give any feedback relating to the degree of inflation of the cuff until there is 20 ml air within it. Even with 15 ml air within the cuff, the appearance and feel of the pilot balloon are somewhat misleading (Fig. 1). The Hudson RCI Sheridan Spiral-Flex reinforced tracheal tube with 15 ml air in the cuff. The pilot balloon appears deflated. We would like to draw attention to this potential hazard when using the Sheridan Spiral-Flex reinforced tracheal tube and would be interested if anyone else has had similar experiences.