You are intubating your patient for respiratory failure. You see the endotracheal tube (ETT) go through the cords, you inflate the cuff, check the ETCO2, secure the ETT and start ventilation. All is well, but do you know how much air to put in the cuff? Are you wondering why this question is important?
What is the purpose of the ETT cuff? A properly inflated cuff maintains the seal for positive pressure ventilation without volume loss while decreasing the incidence of micro-aspiration and ultimately VAP in mechanically ventilated patients. Okay, but how do you know if the cuff is properly inflated? Currently, guidelines for optimal cuff pressure of 20-30cmH2O are regarded as safe. There are numerous devices to measure and monitor cuff pressures.
- The Posey Cufflator is a non-disposable cuff inflator and pressure regulator that attaches to the pilot balloon and allows the clinician to add air or release air depending on the pressure reading.
- The Pyton is a programmable electronic device that continuously maintains consistent optimal cuff pressures at 25cmH2O.
- The AG Cuffill, which is a cuff inflator and pressure regulator is a disposable 10cc syringe that attaches to the pilot balloon and gives a digital reading.
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.
Keeping the appropriate cuff pressure does come with its challenges. Many clinical situations can alter ETT cuff pressures.
- 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.
- 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.
- Placing the appropriate amount of air to generate an appropriate cuff press is key to reducing potential side effects
- Cuff pressure monitoring varies among facilities and dedicated protocols and guidelines are lacking
- Adjustment of cuff pressure guided by subjective measurement may lead to inaccurate cuff pressures
- Khalil, N. S. A., Salama, R. A. M., Mohammed, W. Y., & Sayed, M. S. Factors affecting endotracheal tube cuff pressure measurement: A review of Literature. ARC Journal of Nursing and Healthcare. (2018) https://www.arcjournals.org/journal-of-nursing-and-healthcare/volume-4-issue-4/1