In vitro evaluation of the method effectiveness to limit inflation pressure cuffs of endotracheal tubes^☆

ABSTRACT

BACKGROUND AND OBJECTIVE:

Cuffs of tracheal tubes protect the lower airway from aspiration of gastric contents and facilitate ventilation, but may cause many complications, especially when the cuff pressure exceeds 30 cm H₂O. This occurs in over 30% of conventional insufflations, so it is recommended to limit this pressure. In this study we evaluated the in vitro effectiveness of a method of limiting the cuff pressure to a range between 20 and 30 cm H₂O.

METHOD:

Using an adapter to connect the tested tube to the anesthesia machine, the relief valve was regulated to 30 cm H₂O, inflating the cuff by operating the rapid flow of oxygen button. There were 33 trials for each tube of three manufacturers, of five sizes (6.5-8.5), using three times inflation (10, 15 and 20 s), totaling 1485 tests. After inflation, the pressure obtained was measured with a manometer. Pressure >30 cm H₂O or <20 cm H₂O were considered failures.

RESULTS:

There were eight failures (0.5%, 95% CI: 0.1-0.9%), with all by pressures <20 cm H₂O and after 10 s inflation (1.6%, 95% CI: 0 5-2.7%). One failure occurred with a 6.5 tube (0.3%, 95% CI: -0.3 to 0.9%), six with 7.0 tubes (2%, 95% CI: 0.4-3.6%), and one with a 7.5 tube (0.3%, 95% CI: -0.3 to 0.9%).

CONCLUSION:

This method was effective for inflating tracheal tube cuffs of different sizes and manufacturers, limiting its pressure to a range between 20 and 30 cm H₂O, with a success rate of 99.5% (95% CI: 99.1-99.9%).

Keywords:
Method; Inflation; Cuffs; Tube; Pressure