title: [Detection of air embolism by a re-usable doppler probe integrated in a central venous line].
abstract: OBJECTIVE
  Air embolisms frequently occur during neurosurgical operations. For detection of air embolisms, a re-usable doppler probe, integrated in a central venous line, is described. In an in-vitro test series the measuring sector as well as the function of a 8 MHz doppler probe are presented.
  
  
  METHODS
  The 8 MHz doppler probe is a 1.1 mm diameter cable, into the distal end of which a cylindrical doppler crystal from lead-circonate-titanate (PZT5) of 2 x 1.7 mm is integrated and connected with a doppler unit. The detection of micro bubbles with a volume of 0.4-5 microliters was effected in still liquid for simple measuring of the spatial characteristics of the probe as well as in flowing liquid for simulation of a blood circulation system.
  
  
  RESULTS
  The doppler probe detected qualitatively and reproducibly all gas bubbles offered up to 4 cm around the tip of the probe.
  
  
  CONCLUSIONS
  A reliable detection of micro-bubbles in this test model is possible by means of a 8 Mhz doppler probe. Further animal and clinical studies are planned.
authors.affiliation: Medizinische Klinik I, Klinikum Krefeld, Lutherplatz 40, 47805 Krefeld. o.volk@freenet.de
authors.forename: O
authors.initials: O
authors.lastname: Volk
authors.forename: W
authors.initials: W
authors.lastname: Schnitker
authors.forename: P
authors.initials: P
authors.lastname: Brass
authors.forename: W
authors.initials: W
authors.lastname: Schregel
mesh_terms: D002405:Catheterization, Central Venous / Q000295:instrumentation*; D004618:Embolism, Air / Q000000981:diagnostic imaging*; D006801:Humans; D014463:Ultrasonography