The ideal leak pressure for an uncuffed ETT is 20-30 cm H2O. Remember that a cuffed ETT should be 1/2 size smaller than an uncuffed ETT. If 40 cm H20 or more must be applied to generate a leak, remove the ETT and replace it with something smaller.
Uncuffed ETT are generally used on children 6 years old or younger. But should you ever used an uncuffed tube?
In 2009 a multicenter study comparing Microcuff tubes to uncuffed tubes in 2246 children showed that rates of tube exchange were 2.1% with cuffed compared with 30.8% for conventional tubes (p < 0.0001), and that rates of post-extubation stridor were equal in both groups. Furthermore, the cuff significantly improved the accuracy of the ET monitor. Anesthesia providers could ventilate with an average cuff pressure of 10 cm H20.
Weiss et al. did not look long term and no one can tell if cuffed tubes increase the risk of trachael stenosis in the long run. Historically, with low-volume, high pressure cuffs that was true. Adult, retrospective, and animal data suggest that cuff pressures less than 20 cm H20 in modern tubes are safe.
If you do use a cuff, realize that we are awful at guessing pressures with palpation. We frequently over-inflate and fail to notice that cuff pressures change dramatically during the case, especially if you are using N20. If you use a cuffed tube in a child, ask for one and document the pressures throughout the case.
M Weiss, A Dullenkopf, J E Fischer, C Keller, A C Gerber, European Paediatric Endotracheal Intubation Study Group Prospective randomized controlled multi-centre trial of cuffed or uncuffed endotracheal tubes in small children. Br J Anaesth: 2009, 103(6);867-73
H H Khine, D H Corddry, R G Kettrick, T M Martin, J J McCloskey, J B Rose, M C Theroux, M Zagnoev Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology: 1997, 86(3);627-31; discussion 27A
Marie-Louise Felten, Emmanuelle Schmautz, Sonia Delaporte-Cerceau, Gilles A Orliaguet, Pierre A Carli Endotracheal tube cuff pressure is unpredictable in children. Anesth. Analg.: 2003, 97(6);1612-6