The Matter of Pressure- ETT Cuff Pressures

Why is cuff pressure so important?

The pressure exerted on the tracheal wall is directly related to the ETT cuff pressure.  Tracheal mucosal perfusion decreases when mucosal pressures exceed 30cmH2O and fails to perfuse at pressures of 50cm H20. A cuff pressure exceeding this will reduce or eliminate blood flow to the tissue.  High cuff pressures can cause ischemic injury, mucosal inflammation, tracheal ulcerations, granulation, stenosis, trachea-esophageal fistula, and tracheomalacia.  Hoarseness and stridor, which may require re-intubation, can present as post-extubation side effects due to high cuff pressures.  Low cuff pressures may result in hypoventilation, increased risk of aspiration, pneumonitis, VAP, bronchitis, and loss of tidal volumes.  

Various traditional monitoring methods

• The minimal leak technique is the technique of inflating the ETT with air until there is an absence of an audible air leak then slowly withdraw air until you can hear a minimal leak while still maintaining adequate tidal volumes.  However, this method is still prone to errors.  

• Manual palpation of the pilot balloon consists of feeling the pilot balloon between two fingers to determine if the balloon is firm enough.  This technique often leads to cuff over inflation.

• Bedside manometry directly measures the pressure via the pilot balloon. 

• Direct intracuff monitoring which is a pressure transducer directly attached to the pilot balloon which provides a quantitative pressure reading.

Challenges

Keeping the appropriate cuff pressure does come with its challenges.  Many clinical situations can alter ETT cuff pressures.  

Patient-related factors

• The patient’s head and neck position can cause a change in cuff pressure.  Is the patient’s head rotated, extended, or flexed? 
• The patient’s tracheal diameter.  Is the size of the ETT relative to the size of the trachea in diameter? 
• The patient’s body temperature can play another role. 

Environmental factors

• Duration

Therapeutic interventions

• Quantity of air
• Nitrous oxide
• Manipulation of ETT can create folds

However, there is a wide variation in clinical practices regarding how often to measure the ETT cuff pressure and the proper procedure for cuff inflation.