Annals of Biomedical Engineering

, Volume 21, Issue 4, pp 361–365 | Cite as

Continuous blood density measurement for hemodynamic monitoring: An analysis of its accuracy and sensitivity

  • James R. Ligas
  • Farid Moslehi
  • Mary Anne Farrell Epstein


Continuous measurement of arterial blood density after bolus injection of fluids of different density into the right atrium has been used to measure cardiac output and mean transit time through the central circulation. The transit time distribution for density, however, differs from that for plasma-phase tracers such as indocyanine green. This difference may yield important information about red cell transit times through the microcirculation. We analyzed the potential of the density technique to resolve small changes in transit time distributions. Rayleigh's Method was used to calculate the relationship between density distribution within the U-tube and frequency of oscillation. Fourier integral transformation of a functional representation of indocyanine green dye curves provided an estimate of amplitude versus frequency for likely input density signals. We found that the ability of the densitometer to accurately follow blood density changes depends upon physiologic parameters associated with the experimental animal and upon the physical characteristics of the densitometer itself. Even for small animals, such as a rabbit, the densitometer theoretically has the ability to accurately follow rapid density changes over time.


Indicator dilution curve Blood density 


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Copyright information

© Pergamon Press Ltd. 1993

Authors and Affiliations

  • James R. Ligas
    • 1
  • Farid Moslehi
    • 2
  • Mary Anne Farrell Epstein
    • 3
  1. 1.The Surgical Research CenterThe University of Connecticut School of MedicineFarmington
  2. 2.The Department of AnesthesiologyThe University of Connecticut School of MedicineFarmington
  3. 3.The Department of PharmacologyThe University of Connecticut School of MedicineFarmington

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