The purpose of a leak test is to determine how much pressure it will take to pass flow by an artificial airway as it sets in the tracheal. This information is used to estimate risk of post extubation stridor or airway obstruction from, usually airway swelling.
Current Practice
Current practice guidelines suggest if the pressure required to move flow is higher than 20 cmh20 then the patient will have an increased risk for post extubation stridor and or distress presumably attributed to Airway swelling/inflammation. The trachea could be stented by the ETT and when removed the true diameter will reveal itself, thus becoming much narrower than the current diameter of the ETT. The higher the leak pressure, the higher probability that the airway is being stented by the ETT.
If the leak is >20 cmh20 the practitioner may choose to give a Steroid regiment and wait until the leak improves vs risking posible stridor and/or increase post extubation WOB.
Cuffed Airways and Leak Tests:
Without specific orders, we manage all Airway cuffs via Minimal Occlusion practice. This means we will inflate the cuff until we just lose leak by auscultation, not by waveforms.
This with our zero flow Ti platforms, makes the cuff need equal to the vents PIP need. So if the patient has a PIP of 28, you will have the cuff inflated to 28.
Each shift, four hours before extubation and as requested, we will need to deflate the cuff and auscultate at what pressure until we first hear air flow (leak) as auscultated from the anterior position of the airway. This is then documented under leak pressure in Compass and on the patients Airway card at the HOB. This is the leak test.
Cuffed Airway but Cuff Down
The patient has a cuffed Airway but there isnt a leak even when the cuff is fully deflated. They are on mechanical ventilation and the PIP is 15. Here we would need to bag the patient as we slowly increase the pressure above 15 cmh20 to determine when we start to hear a leak via auscultation. That pressure would be documented under leak pressure and on the patients airway card. The cuff would remain deflated after the test and we would continue to manage it under our cuff management practice.