Cuff Leak Test
Cuff Leak Test 
Chris Nickson
OVERVIEW
The cuff leak test is used to predict risk of post-extubation stridor in intubated patients
Use and interpretation of the test needs to take into account the overall context of the patient’s condition and the management implications
does not exclude obstruction due to supraglottic structures being splinted apart while the ETT is in situ
PROCEDURE
- Suction endotracheal and oral secretions and set the ventilator in the assist control mode with the patient receiving volume-cycled ventilation
- With the cuff inflated, record displayed inspiratory and expiratory tidal volumes to see whether these are similar
- Deflate the cuff
- Directly record the expiratory tidal volume over the next six breathing cycles as the expiratory tidal volume will reach a plateau value after a few cycles
- Average the three lowest values
- The difference between the inspiratory tidal volume (measured before the cuff was deflated) and the averaged expiratory tidal volume (after cuff deflation) is the cuff leak volume
UTILITY
- suggested approach is to use 110 mL or 10% of tidal volume as the cut-off
- >110 mL difference in expiratory tidal volumes before and after cuff down has NPV 98% for post-extubation stridor in the original study by Miller and Cole (essentially rules it out)
- different cut-offs and performance characteristics in different studies (see Ochoa et al, 2009)
- tracheal extubation can still be successful in many patients with a positive test (low value)
- a low value for cuff leak can also be caused by encrusted secretions around the tube rather than by a narrowed upper airway
