title: Ultrasound assessment for extravascular lung water in patients undergoing hemodialysis. Time course for resolution.
abstract: BACKGROUND
  Sonographic B-lines, also known as lung comets, have been shown to correlate with the presence of extravascular lung water (EVLW). Absent in normal lungs, these sonographic findings become prominent as interstitia and alveoli fill with fluid. Characterization of the dynamics of B-lines, specifically their rate of disappearance as volume is removed, has not been previously described. In this study, we describe the dynamics of B-line resolution in patients undergoing hemodialysis.
  
  
  METHODS
  Patients undergoing hemodialysis underwent three chest ultrasound examinations: before, at the midpoint, and after dialysis. We followed a previously described chest ultrasound protocol that counts the number of B-lines visualized in 28 lung zones. Baseline demographics, assessment of ejection fraction, time elapsed, net volume of fluid removed, and subjective degree of shortness of breath were recorded for each patient.
  
  
  RESULTS
  Forty of 45 patients completed full dialysis runs and had all three lung scans performed; 6 of 40 patients had zero or one B-line predialysis, and none of these 6 patients gained B-lines during dialysis. Thirty-four of 40 patients had statistically significant reductions in the number of B-lines from predialysis to the midpoint scan and from predialysis to postdialysis with a p value < 0.001. There was no association between subjective dyspnea scores and number of B-lines removed.
  
  
  CONCLUSIONS
  B-line resolution appears to occur real-time as fluid is removed from the body, and this change was statistically significant. These data support thoracic ultrasound as a useful method for evaluating real-time changes in EVLW and in assessing a patient's physiologic response to the removal of fluid.
  
  
  BACKGROUND
  Massachusetts General Hospital trial registration protocol No. 2007P 002226.
authors.affiliation: Department of Emergency Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA. Electronic address: vnoble@partners.org.
authors.forename: Vicki E
authors.initials: VE
authors.lastname: Noble
authors.affiliation: Department of Emergency Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA.
authors.forename: Alice F
authors.initials: AF
authors.lastname: Murray
authors.affiliation: Department of Emergency Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA.
authors.forename: Roberta
authors.initials: R
authors.lastname: Capp
authors.affiliation: Department of Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA.
authors.forename: Mary H
authors.initials: MH
authors.lastname: Sylvia-Reardon
authors.affiliation: Department of Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA.
authors.forename: David J R
authors.initials: DJR
authors.lastname: Steele
authors.affiliation: Department of Emergency Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Liteplo
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015633:Extravascular Lung Water / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011336:Probability; D011446:Prospective Studies; D011654:Pulmonary Edema / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D006435:Renal Dialysis / Q000009:adverse effects* / Q000379:methods; D015203:Reproducibility of Results; D018570:Risk Assessment; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler; D055815:Young Adult