Background and Goal of Study: Pressure within an endotracheal tube cuff should be maintained between 20–30 cmH2O to prevent damage to the tracheal wall. However, cuff pressures are rarely measured, although clinicians poorly estimated cuff pressure. Our goal was thus to predict cuff volume that would produce optimal cuff pressure from tracheal diameter (as determined from chest radiography) or from patient height and age.
Materials and Methods: In the development phase, initial cuff pressure and cuff volume were measured in 244 patients. Optimal cuff volume was determined in each, defined as the volume half-way between those required to produce cuff pressures of 20 and 30 cm H2O. We calculated regression equations between optimal cuff volume and tracheal diameter, and between optimal cuff volume and the combination of height and age. Our primary outcome was the proportion of patients who had cuff pressure 20–30 cm H2O when cuff volume was selected by each regression formula.
Results and Discussion: There was a good correlation between optimal cuff volume and tracheal diameter on chest X-ray (R2 = 0.83), and a moderate correlation between optimal ICV and both height and age (R2 = 0.44). Predicted cuff volume was more likely to give optimal cuff pressure when based on tracheal diameter (65% of patients) and when based on both height and age (45%) compared with in the development phase (28%) (P<0.05).
Conclusion(s): Optimal cuff volume can be better estimated from tracheal diameter, as determined radiographically, than by patient height and age. However, even the formula based on tracheal diameter proved inadequate in 35% of patients. Existing formulae cannot substitute for manometry.
1 Sengupta P, Sessler DI, Maglinger P, et al. Endotracheal tube cuff pressure in three hospitals, and the volume required to produce an appropriate cuff pressure. BMC Anesthesiol 2004;4:8.