title: High-intensity intermittent exercise increases pulmonary interstitial edema at altitude but not at simulated altitude.
abstract: OBJECTIVE
  Ascent to high altitude leads to a reduction in ambient pressure and a subsequent fall in available oxygen. The resulting hypoxia can lead to elevated pulmonary artery (PA) pressure, capillary stress, and an increase in interstitial fluid. This fluid can be assessed on lung ultrasound (LUS) by the presence of B-lines. We undertook a chamber and field study to assess the impact of high-intensity exercise in hypoxia on the development of pulmonary interstitial edema in healthy lowlanders.
  
  
  METHODS
  Thirteen volunteers completed a high-intensity intermittent exercise (HIIE) test at sea level, in acute normobaric hypoxia (12% O2, approximately 4090 m equivalent altitude), and in hypobaric hypoxia during a field study at 4090 m after 6 days of acclimatization. Pulmonary interstitial edema was assessed by the evaluation of LUS B-lines.
  
  
  RESULTS
  After HIIE, no increase in B-lines was seen in normoxia, and a small increase was seen in acute normobaric hypoxia (2 ± 2; P < .05). During the field study at 4090 m, 12 participants (92%) demonstrated 7 ± 4 B-lines at rest, which increased to 17 ± 5 immediately after the exercise test (P < .001). An increase was evident in all participants. There was a reciprocal fall in peripheral arterial oxygen saturations (Spo2) after exercise from 88% ± 4% to 80% ± 8% (P < .01). B-lines and Spo2 in all participants returned to baseline levels within 4 hours.
  
  
  CONCLUSIONS
  HIIE led to an increase in B-lines at altitude after subacute exposure but not during acute exposure at equivalent simulated altitude. This may indicate pulmonary interstitial edema.
authors.affiliation: Department of Anesthesia, St George's Healthcare NHS Trust, London, UK (Dr Edsell). Electronic address: mark.edsell@stgeorges.nhs.uk.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Edsell
authors.affiliation: Greater Sydney Area Helicopter Emergency Medical Service, Sydney, Australia (Dr Wimalasena); University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK (Drs Wimalasena and Imray).
authors.forename: Yashvi H
authors.initials: YH
authors.lastname: Wimalasena
authors.affiliation: School of Medicine, University of Birmingham, Birmingham, UK (Drs Malein and Wright).
authors.forename: William L
authors.initials: WL
authors.lastname: Malein
authors.affiliation: Department of Sport & Exercise Sciences, University of Chichester, Chichester, UK (Drs Ashdown, Gallagher, and Myers).
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Ashdown
authors.affiliation: Department of Sport & Exercise Sciences, University of Chichester, Chichester, UK (Drs Ashdown, Gallagher, and Myers).
authors.forename: Carla A
authors.initials: CA
authors.lastname: Gallagher
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK (Drs Wimalasena and Imray); Warwick Medical School, Coventry, UK (Dr Imray).
authors.forename: Chris H
authors.initials: CH
authors.lastname: Imray
authors.affiliation: School of Medicine, University of Birmingham, Birmingham, UK (Drs Malein and Wright).
authors.forename: Alex D
authors.initials: AD
authors.lastname: Wright
authors.affiliation: Department of Sport & Exercise Sciences, University of Chichester, Chichester, UK (Drs Ashdown, Gallagher, and Myers).
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Myers
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011654:Pulmonary Edema / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018434:Sickness Impact Profile; D014463:Ultrasonography
keywords: altitude; exercise; high altitude pulmonary edema; ultrasound