[Evaluation of a pressure and volume-relief instrument (modified Brandt's rediffusion system) to prevent increase in endotracheal tube cuff pressure].

Nitrous oxide diffuses into the endotracheal tube cuff and then overexpand the cuff. This causes upper airway obstruction and trauma in intubated patient during general anesthesia. We evaluated the efficacy and a safety of a pressure and volume-relief instrument (modified Brandt's rediffusion system), which can easily be made by ourselves, to prevent increases in endotracheal tube cuff pressure. Fourteen intubated patients under general anesthesia with nitrous oxide and oxygen were randomly allocated into two groups: in one group (control group, n = 7), endotracheal tube cuffs were inflated by air at time of intubation; in other group (rediffusion group, n = 7), tube cuffs were inflated by air and thereafter a pressure and volume-relief instrument (modified Brandt's rediffusion system) was attached to the end of pilot balloon. Pressure of endotracheal tube cuffs was monitored and recorded until the extubation. Time interval until the pressure of tube cuffs increased more than 23 mmHg, which inhibit the local circulation on the tracheal cartilage, in rediffusion group (274.7 +/- 95.9 min) was significantly longer than the duration in control group (64.7 +/- 23.5 min). We conclude that the rediffusion instrument is effective and safe to prevent the rise in the pressure of an endotracheal tube cuff.