Endotracheal Tube Cuff Management at Altitude

Abstract : Care of the mechanically ventilated patient during aeromedical transport presents a number of challenges owing to the impact of alterations in barometric pressure on gas volumes and gas density. Hypobarism reduces the partial pressure of oxygen in the atmosphere, which can lead to hypoxia and causes expansion of gas trapped in closed spaces. In the latter case, gas trapped in the body (pneumothorax, bowel gas) or in devices (endotracheal tube (ETT) cuffs, pneumatic tourniquets) expands during ascent and contracts on descent. We designed a model study of endotracheal intubation including mechanical ventilation and four methods of cuff pressure management during ascent and descent aboard a Critical Care Air Transport Team training flight. The results of this study confirm previous work demonstrating a significant rise in ETT cuff pressure during ascent to 8,000 feet. Our data also demonstrate that while filling the ETT cuff with saline reduces the impact of altitude-related changes in cuff pressure, the initial cuff pressure exceeds the pressure associated with interruption of mucosal blood flow. The passive-acting PressureEasy device reduced the altitude-related change in pressure but did not eliminate the pressure changes, nor could it prevent the low pressures seen on descent.