The cuff pilot balloon is one of the safety features of the ETT, which has received some attention from the examiners. More on this topic is written elsewhere. Suffice to say, this little bubble is a goldmine of information; however, paradoxically, what it doesn't tell you is the cuff pressure. Ample evidence exists to suggest that senior anaesthetists, veteran ED doctors and practicing paramedics can neither generate nor estimate cuff pressures using the pilot balloon.

Causes of a "zero" cuff pressure reading

Consequences of an overpressured cuff balloon

References

Janossy, K. M., et al. "The effect of pilot balloon design on estimation of safe tracheal tube cuff pressure." Anaesthesia 65.8 (2010): 785-791.

Hoffman, Robert J., Vivek Parwani, and In-Hei Hahn. "Experienced emergency medicine physicians cannot safely inflate or estimate endotracheal tube cuff pressure using standard techniques." The American journal of emergency medicine 24.2 (2006): 139-143.

Parwani, Vivek, et al. "Practicing paramedics cannot generate or estimate safe endotracheal tube cuff pressure using standard techniques." Prehospital Emergency Care 11.3 (2007): 307-311.