title: Factors associated with B-lines after exposure to hypobaric hypoxia.
abstract: OBJECTIVE
  Increased extravascular lung water (EVLW) is seen as B-lines on chest ultrasonography. In lowlanders ascending to altitude the time course, relationship with the patient's clinical status and factors affecting B-lines are still unclear. The aim was to monitor B-lines, clinical status and N-terminal B-type natriuretic peptide (NT-proBNP) during exposure to high altitude.
  
  
  RESULTS
  Chest ultrasonography, blood samples, cardiovascular parameters, and signs and symptoms of high altitude pulmonary oedema (HAPE) were prospectively assessed in 19 participants at baseline and after ascent to 3830 m (9, 24, 48, 72 h, and 8 days) by blinded investigators. Potential confounding factors (e.g. altitude variations, physical effort) were minimized. Generalized estimating equations were used to analyse factors associated with B-lines. B-lines changed with exposure to altitude (P = 0.006) in a parabolic-like pattern within the first 72 h; 10 of 18 participants (55.6%) had >5 B-lines at 24 h. B-lines were correlated with the number of signs and symptoms (partial coefficient = 0.372, P = 0.001). B-lines were associated with time (P = 0.038), sex (P = 0.013), and SpO2 (P = 0.042), but not with NT-proBNP (P = 0.546). The participant with a clinical diagnosis of HAPE had 23 B-lines.
  
  
  CONCLUSIONS
  B-lines during exposure to altitude seem to reflect the individual response to hypobaric hypoxia and represent clinically relevant alterations at high altitude, also in patients with HAPE. Similar to previous studies, our results support a non-cardiogenic aetiology of B-lines.
authors: EURAC Institute of Mountain Emergency Medicine, Viale Druso 1, Bolzano 39100, Italy giacomo.strapazzon@eurac.edu.
authors: Giacomo
authors: G
authors: Strapazzon
authors: Department of Radiology, University Hospital of Padova, Padova, Italy.
authors: Roberto
authors: R
authors: Vezzaro
authors: Department of Anesthesiology and Critical Care Medicine, General Hospital of Silandro, Silandro, Italy.
authors: Georg
authors: G
authors: Hofer
authors: EURAC Institute of Mountain Emergency Medicine, Viale Druso 1, Bolzano 39100, Italy.
authors: Tomas
authors: T
authors: Dal Cappello
authors: EURAC Institute of Mountain Emergency Medicine, Viale Druso 1, Bolzano 39100, Italy.
authors: Emily
authors: E
authors: Procter
authors: EURAC Institute of Mountain Emergency Medicine, Viale Druso 1, Bolzano 39100, Italy.
authors: Karla
authors: K
authors: Balkenhol
authors: Department of Laboratory Medicine, General Hospital of Merano, Merano, Italy.
authors: Stefan
authors: S
authors: Platzgummer
authors: EURAC Institute of Mountain Emergency Medicine, Viale Druso 1, Bolzano 39100, Italy.
authors: Hermann
authors: H
authors: Brugger
mesh_terms: D000328:Adult; D000532:Altitude Sickness / Q000000981:diagnostic imaging*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging*; D000860:Hypoxia / Q000000981:diagnostic imaging*; D007558:Italy; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010092:Oximetry; D010446:Peptide Fragments / Q000097:blood; D011446:Prospective Studies; D056152:Respiratory Rate / Q000502:physiology; D014463:Ultrasonography
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain
keywords: high altitude pulmonary oedema; hypobaric hypoxia; lung; natriuretic peptide; ultrasonography