Non-invasive studies of peripheral vascular compliance using a non-occluding photoplethysmographic method

E. A. López-Beltrán, P. L. Blackshear, Stanley M Finkelstein, Jay N Cohn

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49 Scopus citations


A non-invasive technique is implemented to measure a peripheral vascular compliance index Cindex, using an infrared photoplethysmographic waveform as an indicator of intravascular volume change and a continuous blood pressure monitor to measure the blood pressure during each heart-beat. The non-linear behaviour of Cindex with pressure and the effect of age on Cindex are studied in 62 males (15-73 years). Repeatability tests and the effect of ice-water exposure of a portion of a limb are studied in 10 and 14 subjects, respectively. For each individual, Cindex measurements are taken at discrete values of local mean arterial pressure (Pmean), and a Cindex against Pmean plot is obtained. There is a statistically significant difference (p<0.05) in Cindex tor the lower values of Pmean (60-100 mmHg) between two age groups formed (15-52 and 58-73 years). The cold-pressor test (CPT) shows a 68% median decrease in Cindex, with an inter-quartile range of 60-77%, in a matter of seconds. The results suggest that Cindex may be a useful noninvasive indicator of peripheral vascular compliance in humans.

Original languageEnglish (US)
Pages (from-to)748-753
Number of pages6
JournalMedical and Biological Engineering and Computing
Issue number6
StatePublished - 1998

Bibliographical note

Funding Information:
Acknowledgments--This work was supported by NIH (MARC Predoctoral Research Fellowship, Grant F31 GM 09586-06). We would like to thank Dr Phillip Isaacson (Vice President, NONIN MEDICAL, Inc.) for providing a pulse oximeter for this study.


  • Age-effect
  • Non-invasive compliance
  • Peripheral compliance
  • Photoplethysmography
  • Pressure-dependent compliance
  • Repeatability


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