Tuesday August 29, 2006
Endotracheal Tube Cuff Pressure and VAP (Ventilator-associated pneumonia)


As we are learning more and more about dangers of Ventilator-associated pneumonia (VAP), we are in constant quest of finding factors influencing its occurance, rate and resolution.

There are 2 basic objectives for inflated cuff of ETT (endotracheal tube) 1) to abolish air leak around ETT 2) to prevent aspiration of pharyngeal contents into the trachea. ICUs use any level of cuff pressure from 20 cm H2O to 30 cm H2O in ETT ( 25 cm H2O is thought to be sufficient). The concern always is that with increasing the cuff pressure beyond any given threshold, it may compromise mucosal blood supply and may result in subglottic stenosis. Tracheal mucosal ischemia occurs when endotracheal tube cuff pressure exceeds above 34 cm H2O (some suggests it is safe till 40 cm H2O).

We learned that (and its now part of some VAP bundles) that continuous aspiration of subglottic secretions (CASS) helps in preventing VAP. Echoing on the same note Drs. Chendrasekhar and Timberlake from Trauma Services, Iowa Methodist Medical Center, Des Moines, Iowa tried to find the threshold below which subglottic secretions cross the balloon barrier. They used 10 ex-vivo tracheas obtained from previously euthanized pigs. They found that: The average ETT cuff pressure required to maintain secretions above the cuff was 29.5 ± 3.2 cm H2O 1.

This is a very small in-vivo study and in no way provide any guideline. More work is required but it tells us that this is an important aspect to explore in preventing VAP.

Automatic regulation of the cuff pressure in endotracheally-intubated patients: R. Farré and co. had previuosly reported a device that can provide automatic and continuous regulation of cuff pressure in protecting the trachea from tissue damage and for reducing the risk of ventilator-associated pneumonia 2.


Addendum: This is not a common practice in ICUs to utilize manometer to measure ETT cuff pressure. One recent study of 93 patients found that only 27% of pressures were within 20 - 30 cmH2O and actually 27% exceeded 40 cmH2O. Neither patient morphometrics, institution, experience of anesthesia provider, nor tube size influenced measured cuff pressure !! 3.

Is it time to do manometric cuff pressure everyday on our intubated patients?


References: click to get abstract/artice

1. Endotracheal Tube Cuff Pressure Threshold for Prevention of Nosocomial Pneumonia - The Journal of Applied Research - Voulme 3 issue 3.
2. Automatic regulation of the cuff pressure in endotracheally-intubated patients - Eur Respir J 2002; 20:1010-1013
3. Endotracheal tube cuff pressure in three hospitals, and the volume required to produce an appropriate cuff pressure - BMC Anesthesiol. 2004; 4: 8