title: Reproducibility and variability of digital thermal monitoring of vascular reactivity.
abstract: BACKGROUND
  Previous studies demonstrated that digital thermal monitoring (DTM) of vascular reactivity, a new test for vascular function assessment, is well correlated with Framingham Risk Score, coronary calcium score and CT angiography. This study evaluates the variability and reproducibility of DTM measurements. We hypothesized that DTM is reproducible, and its variability falls within the accepted range of clinical diagnostic tests.
  
  
  METHODS
  A fully automated DTM device (VENDYS, Endothelix Inc., Houston, TX, USA) was used for repeated measurement of vascular function in 18 healthy volunteers (age 35 ± 4 years, 74% men) after 24 h. All subjects underwent overnight fasting, and the test was preceded by 30-min rest in a supine position inside a dimmed room with temperature 22-24°C. The measurements were obtained during and after a 2-min supra systolic arm-cuff occlusion-induced reactive hyperaemia procedure. As a part of this study, the Doppler ultrasound hyperaemic, low-frequency, blood velocity of radial artery and a fingertip DTM of vascular function were compared simultaneously. Postcuff deflation temperature rebound and area under the curve, DTM indices of vascular function, were studied.
  
  
  RESULTS
  Temperature rebound area under the curve correlated closely with Doppler hyperaemic, low-frequency, blood velocity (r = 0·97, P = 0·0001). Day-to-day intra-subject variability was 6·2% for baseline temperature, 8·7% for mean blood pressure and 11·4% for heart rate. The coefficient of repeatability of temperature rebound and area under the curve were 2·4% and 2·8%.
  
  
  CONCLUSIONS
  In a controlled environment, the repeatability of DTM is excellent. DTM can be used as a reproducible and operator-independent test for non-invasive measurement of vascular function.
authors: Los Angeles Biomedical Research Institute at Harbor UCLA Medical Center, Torrance, CA 90502, USA.
authors: Naser
authors: N
authors: Ahmadi
authors: Gary L
authors: GL
authors: McQuilkin
authors: Mohammad W
authors: MW
authors: Akhtar
authors: Fereshteh
authors: F
authors: Hajsadeghi
authors: Stanley J
authors: SJ
authors: Kleis
authors: Harvey
authors: H
authors: Hecht
authors: Morteza
authors: M
authors: Naghavi
authors: Matthew
authors: M
authors: Budoff
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001783:Blood Flow Velocity; D001794:Blood Pressure; D003250:Constriction; D004867:Equipment Design; D005260:Female; D005385:Fingers / Q000098:blood supply*; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008422:Materials Testing; D015588:Observer Variation; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012881:Skin Temperature; D013781:Texas; D013817:Thermography / Q000295:instrumentation*; D013997:Time Factors; D018608:Ultrasonography, Doppler