Altitude-Related Change in Endotracheal Tube Cuff Pressures in Helicopter EMS

Over-inflation of endotracheal tube (ETT) cuffs has the potential to lead to scarring and stenosis of the trachea.1, 2,3, 4 The air inside an ETT cuff is subject to expansion as atmospheric pressure decreases, as happens with an increase in altitude. Emergency medical services helicopters are not pressurized, thereby providing a good environment for studying the effects of altitude changes ETT cuff pressures. This study aims to explore the relationship between altitude and ETT cuff pressures in a helicopter air-medical transport program.

ETT cuffs were initially inflated in a nonstandardized manner and then adjusted to a pressure of 25 cmH₂O. The pressure was again measured when the helicopter reached maximum altitude. A final pressure was recorded when the helicopter landed at the receiving facility.

We enrolled 60 subjects in the study. The mean for initial tube cuff pressures was 70 cmH₂O. Maximum altitude for the program ranged from 1,000-3,000 feet above sea level, with a change in altitude from 800-2,480 feet. Mean cuff pressure at altitude was 36.52 ± 8.56 cmH₂O. Despite the significant change in cuff pressure at maximum altitude, there was no relationship found between the maximum altitude and the cuff pressures measured.

Our study failed to demonstrate the expected linear relationship between ETT cuff pressures and the maximum altitude achieved during typical air-medical transportation in our system. At altitudes less than 3,000 feet above sea level, the effect of altitude change on ETT pressure is minimal and does not require a change in practice to saline-filled cuffs.