title: Formation of edema and fluid shifts during a long-haul flight.
abstract: BACKGROUND
  More than 1.5 billion passengers travel by aircraft every year. Leg edema, as a sign of venous stasis, is a well-known problem among passengers during and after long-haul flights. Until now, no studies have been done on the development of leg edema and fluid shifts under real flight conditions. The aim of our study was to evaluate edema formation in the leg and to investigate possible fluid shifts to the interstitial space under real flight conditions.
  
  
  METHODS
  Twenty participants, 10 without risk and 10 with moderate risk for venous thrombosis, were selected. They flew from Vienna to Washington, flight time 9 h, and returned 2 days later. Investigations were done 48 h before the flight, between the fifth and eighth flight hour on board to Washington and back to Vienna, immediately after arrival in Vienna, and 1 and 3 days after arrival. Plethysmographic measurements were carried out using an optoelectronic scanner system (Perometer). Thickness of the skin was measured at the forehead and in front of the tibia.
  
  
  RESULTS
  There were no differences in all measurements between both groups. The volume of the leg increased from 8242 +/- 1420 mL to 8496 +/- 1474 mL after the flight (p <.001). Volume accumulation was distributed to the lower leg as well as to the thigh. Skin thickness in front of the tibia increased significantly during the flight (p <.05), and remained elevated 1 day after arrival.
  
  
  CONCLUSIONS
  We have demonstrated that long-haul flights induce significant fluid accumulation in the lower extremity, involving the lower leg and thigh. This increase in tissue thickness was maintained for some days after the flights.
authors.affiliation: Clinic for Anesthesia and Intensive Care Medicine, The Leopold Franzens University of Innsbruck, Innsbruck, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Mittermayr
authors.forename: Dietmar
authors.initials: D
authors.lastname: Fries
authors.forename: Petra
authors.initials: P
authors.lastname: Innerhofer
authors.forename: Beatrix
authors.initials: B
authors.lastname: Schobersberger
authors.forename: Anton
authors.initials: A
authors.lastname: Klingler
authors.forename: Hugo
authors.initials: H
authors.lastname: Partsch
authors.forename: Uwe
authors.initials: U
authors.lastname: Fischbach
authors.forename: Hanns-Christian
authors.initials: HC
authors.lastname: Gunga
authors.forename: Eberhard
authors.initials: E
authors.lastname: Koralewski
authors.forename: Karl
authors.initials: K
authors.lastname: Kirsch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schobersberger
mesh_terms: D000328:Adult; D000401:Aircraft; D004326:Drinking; D004487:Edema / Q000097:blood / Q000503:physiopathology*; D005260:Female; D018495:Fluid Shifts / Q000502:physiology*; D006400:Hematocrit; D006801:Humans; D007866:Leg; D008297:Male; D018570:Risk Assessment; D012867:Skin / Q000473:pathology; D013997:Time Factors; D014195:Travel