Intratracheal Cuffs and Aeromedical Evacuation

Pressure in the cuffs of tracheal tubes at altitude

“…This is a commonly used ascent rate by commercial aircraft, air ambulances and helicopters. Previous studies have used ascent rates exceeding this: 12 000 ft.min −1 [2] and 4000 ft.min −1 [3], with the possibility of overestimation of the cuff pressure due to differing dynamic and static compliances.…”

“…Only two studies of cuff pressure in tracheal tubes at altitude were found in a Medline search (1960–2001). The first [2] used anaesthetised dogs. They were decompressed to 8000 ft over 40 s, kept at that altitude for 60 s and then decompressed over 60 s to 35 000 ft for 60 s. Readings were taken at 8000 and 35 000 ft. Six types of tracheal tubes with four different types of cuffs were evaluated: Rusch and Portex (low volume, high pressure), Shiley and Foregger (high volume, low pressure), Kamen‐Willkinson (foam rubber cuff) and McGinnis (high volume with attached control balloon).…”

“…Tracheal mucosal blood flow in humans has been shown to be compromised at lateral wall pressures above 30 cmH 2 O (22 mmHg), with cessation of flow to the mucosa over the tracheal rings and posterior tracheal wall at a lateral wall pressure (critical perfusion pressure) of 50 cmH 2 O (37 mmHg) [1]. Cuff pressure in tracheal tubes increases with altitude, having been studied at 8000, 10 000 and 35 000 ft [2, 3].…”

Pressures within air‐filled tracheal cuffs at altitude – an in vivo study

“…There have not been any studies investigating tracheal tube cuff pressures at altitude in vivo . The first study reported pressures within the cuffs in intubated dogs of six different makes of tubes at 8000 ft, and again following an explosive decompression to 35 000 ft, unacceptably high pressures were found [1]. However, explosive decompressions are rare, and the tracheal anatomy of dogs differs from that of critically ill humans.…”

“…There have been several studies that have investigated the effects of increasing altitude on the pressure within air‐filled tracheal tube cuffs [1–3]. However, none have been performed on human subjects at clinically relevant altitudes.…”