title: Monitoring of arterial stiffness indices by applanation tonometry and pulse wave analysis: reproducibility at low blood pressures.
abstract: OBJECTIVE
  Aortic pulse wave analysis (PWA) reveals valuable information related to several hemodynamic characteristics mainly in normotensive and hypertensive patients. The main indices determined by PWA are augmentation index (AI) and reflection time index (RTI), which provide an indirect estimate of arterial stiffness and pulse wave velocity. The objective of the present study was to assess the reproducibility of aortic AI and RTI obtained by an automated and commercially available system (SphygmoCor) applied in patients with low blood pressures where such data are lacking.
  
  
  METHODS
  The study population consisted of 19 patients with cardiogenic shock due to acute myocardial infarction who underwent mechanical assistance with intraaortic balloon pump. Aortic pressure waveforms were derived from peripheral waveforms--recorded by applanation tonometry of the radial artery--by applying generalized transfer functions. On every occasion, a well-trained operator performed two measurements with 2 min interval. Multiple pairs of measurements were obtained per patient in order to study a wide range of different hemodynamic conditions. Thus, a total of 91 pairs of measurements were performed and analyzed using Bland-Altman plots.
  
  
  RESULTS
  AI and RTI ranged within 30-184% and 10-27%, respectively. Within-observer difference was 0.10 +/- 5.82% for aortic AI and 0.14 +/- 1.2% for RTI.
  
  
  CONCLUSIONS
  Pulse wave analysis and radial artery tonometry can be used to measure AI and RTI with satisfactory reproducibility even in low blood pressures. Ongoing research is required to establish PWA utility in clinical practice especially at patients with low blood pressures.
authors.affiliation: Department of Clinical Therapeutics, Alexandra Hospital, School of Medicine, National and Kapodistrian University of Athens, Greece. theopap@mail.ntua.gr
authors.forename: Theodoros G
authors.initials: TG
authors.lastname: Papaioannou
authors.forename: Kimon S
authors.initials: KS
authors.lastname: Stamatelopoulos
authors.forename: Elias
authors.initials: E
authors.lastname: Gialafos
authors.forename: Charalambos
authors.initials: C
authors.lastname: Vlachopoulos
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Karatzis
authors.forename: John
authors.initials: J
authors.lastname: Nanas
authors.forename: John
authors.initials: J
authors.lastname: Lekakis
mesh_terms: D000368:Aged; D001331:Automation; D015924:Blood Pressure Monitors; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006973:Hypertension / Q000175:diagnosis*; D008297:Male; D008365:Manometry; D008875:Middle Aged; D011674:Pulse; D017534:Radial Artery / Q000502:physiology*; D015203:Reproducibility of Results; D014655:Vascular Resistance