title: Chest ultrasonography for the diagnosis and monitoring of high-altitude pulmonary edema.
abstract: BACKGROUND
  The comet-tail technique of chest ultrasonography has been described for the diagnosis of cardiogenic pulmonary edema. This is the first report describing its use for the diagnosis and monitoring of high-altitude pulmonary edema (HAPE), the leading cause of death from altitude illness.
  
  
  METHODS
  Eleven consecutive patients presenting to the Himalayan Rescue Association clinic in Pheriche, Nepal (4,240 m) with a clinical diagnosis of HAPE underwent one to three chest ultrasound examinations using the comet-tail technique to determine the presence of extravascular lung water (EVLW). Seven patients with no evidence of HAPE or other altitude illness served as control subjects. All examinations were read by a blinded observer.
  
  
  RESULTS
  HAPE patients had higher comet-tail score (CTS) [mean +/- SD, 31 +/- 11 vs 0.86 +/- 0.83] and lower oxygen saturation (O(2)Sat) [61 +/- 9.2% vs 87 +/- 2.8%] than control subjects (p < 0.001 for both). Mean CTS was higher (35 +/- 11 vs 12 +/- 6.8, p < 0.001) and O(2)Sat was lower (60 +/- 11% vs 84 +/- 1.6%, p = 0.002) at hospital admission than at discharge for the HAPE patients with follow-up ultrasound examinations. Regression analysis showed CTS was predictive of O(2)Sat (p < 0.001), and for every 1-point increase in CTS O(2)Sat fell by 0.67% (95% confidence interval, 0.41 to 0.93%, p < 0.001).
  
  
  CONCLUSIONS
  The comet-tail technique effectively recognizes and monitors the degree of pulmonary edema in HAPE. Reduction in CTS parallels improved oxygenation and clinical status in HAPE. The feasibility of this technique in remote locations and rapid correlation with changes in EVLW make it a valuable research tool.
authors.affiliation: MFA, Department of Emergency Medicine, Clinics 115, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02140, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Fagenholz
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Gutman
authors.forename: Alice F
authors.initials: AF
authors.lastname: Murray
authors.forename: Vicki E
authors.initials: VE
authors.lastname: Noble
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Thomas
authors.forename: N Stuart
authors.initials: NS
authors.lastname: Harris
mesh_terms: D000328:Adult; D000531:Altitude; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011653:Pulmonary Diffusing Capacity; D011654:Pulmonary Edema / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014463:Ultrasonography