title: Endotracheal tube and laryngeal mask airway cuff pressures can exceed critical values during ascent to higher altitude.
abstract: OBJECTIVE
  Tracheal mucosal perfusion is compromised at an endotracheal tube (ETT) cuff pressure of 30 cm H(2)O, and blood flow is obstructed at a pressure of 50 cm H(2)O.
  
  
  METHODS
  We measured the change in pressure of air-filled cuffs of 6.0 and 7.5 ETTs and a size 4 laryngeal mask airway (LMA) from sea level to 2400 m. The ETTs and LMA cuff measurements were done with the devices uncontained, and an additional 6.0 ETT was placed in a 10-mL syringe barrel to mimic placement in a trachea. This restricted cuff expansion simulating what would occur when it is placed within the trachea. The pressure of fluid-filled 6.0 ETT cuffs was also measured.
  
  
  RESULTS
  Intracuff pressure increases linearly with increasing altitude, in all air-filled ETT and LMAs. Water-filled cuffs demonstrated no significant change in pressure with changes in altitude. The rate of ETT cuff pressure increase was greater for the ETT restricted within the syringe barrel compared with the unrestricted ETT cuff. The rate of LMA cuff pressure increase was greater than the rate of increase for all the ETTs (restricted and unrestricted).
  
  
  CONCLUSIONS
  This model indicates that ETT cuffs inflated before air transport are likely to exceed critical pressure levels rapidly during flight. In addition, there will be loss of ETT cuff pressure, with loss of a good seal, during descent if a cuff is initially inflated at peak altitudes. Therefore, we suggest ETT cuff pressures should be monitored and adjusted continuously during ascent and decent.
authors.affiliation: Department of Pediatrics, University of Hawaii John A. Burns School of Medicine, Honolulu, HI, USA.
authors.forename: Renee M
authors.initials: RM
authors.lastname: Miyashiro
authors.forename: Loren G
authors.initials: LG
authors.lastname: Yamamoto
mesh_terms: D000399:Air Pressure; D000531:Altitude; D002648:Child; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D017214:Laryngeal Masks; D007820:Laryngeal Mucosa / Q000502:physiology; D010614:Pharynx / Q000502:physiology*; D011312:Pressure