Decrease in cuff pressure during the measurement procedure: an experimental study

To prevent endotracheal tube (ETT)-related complications during mechanical ventilation, ETT cuff pressure should be kept within proper range. In clinical settings, cuff pressure often decreases from target values.

We performed an experimental study to investigate the effects of measuring devices and endotracheal tubes on change in cuff pressure. We continuously measured cuff pressure by inserting a three-way stopcock in the middle of an ETT pilot balloon system. After adjusting the cuff pressure to 24 cmH2O, we disconnected and reconnected each cuff inflator to the inflation valve of the ETT and measured the changes in the cuff pressure. We measured the change in cuff pressure with different ETT sizes, cuff shapes, brands of cuff inflator, and with and without added extension tubes.

The cuff pressure decreased, on average, by 6.6 cmH2O (standard deviation 1.9), when connecting the cuff inflator to the pilot balloon. The measured cuff pressure was less than 20 cmH2O in 67% of the tests. The cuff pressure decreased more when an extension tube was used. The brand of cuff inflator made no difference to the pressure loss. The cuff pressure decreased more with ETTs of smaller size and with ETTs with pyriform cuffs.

Procedures to connect cuff inflators to inflation valves resulted in the loss of cuff pressure by 6.6 cmH2O on average.