title: Vascular distribution of an ultrasound contrast agent used to simulate decompression bubbles.
abstract: OBJECTIVE
  The objectives of this preliminary work were to evaluate the distribution of an ultrasound contrast agent (UCA) (microbubbles) in different arterial regions (brain, kidney, lower limbs) using the Doppler spectrum brightness analysis and to discuss the results in the context of decompression physiology.
  
  
  METHODS
  There were four patients who instrumented with two pulsed Doppler sensors in order to monitor in real-time the spectrum of the middle cerebral femoral arteries. Renal arteries were investigated using an echo-Doppler probe handled by a sonographer. Measurements of the systolic mean, diastolic frequencies, qualitative, and quantitative analysis of the spectrum brightness intensity were performed before and after intravenous injection of a UCA.
  
  
  RESULTS
  All of the systolic mean and diastolic arterial frequencies remained constant during the experiment. Some seconds after the first injection, the cerebral spectrum was heterogeneously enhanced with strong flashes over the entire spectrum. The renal and femoral spectrums were homogeneously reinforced. The spectrum brightness patterns did not change during the first 10 min.
  
  
  CONCLUSIONS
  This work shows that the distribution of the UCA microbubbles within the vessel sections changed according to the distance from the heart, as suggested by the spectrum recorded at different sites. By mixing the blood, the heart could re-aggregate the UCA particles, even when they returned from the distal vascular regions where they were homogeneously distributed. The circulating microbubbles and their distribution within the arteries should be considered in decompression procedures with repetitive dives.
authors.affiliation: Service de Neurophysiologie Clinique, Université de Poitiers, CHU de Poitiers, 2 rue de la Milétrie, 86021 Poitiers, France. s.besnard@chu-poitiers.fr
authors.forename: Stephane
authors.initials: S
authors.lastname: Besnard
authors.forename: Arnaud
authors.initials: A
authors.lastname: Capri
authors.forename: Michel
authors.initials: M
authors.lastname: Philippot
authors.forename: Philippe
authors.initials: P
authors.lastname: Hervé
authors.forename: Marie-Annick
authors.initials: MA
authors.lastname: Porcher
authors.forename: Philippe
authors.initials: P
authors.lastname: Arbeille
mesh_terms: D000328:Adult; D002536:Cerebral Arteries / Q000378:metabolism*; D003287:Contrast Media / Q000378:metabolism*; D003665:Decompression Sickness / Q000378:metabolism; D005260:Female; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D008297:Male; D045423:Microbubbles; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D012077:Renal Artery / Q000378:metabolism*; D018617:Ultrasonography, Doppler, Pulsed
chemical_list: D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508