Evaluating the State of Microvessels by Minimum Rise Time (MRT01)
Condition: Healthy
Study type: Interventional

Summary: 
      Photoplethysmography (PPG) is a simple uncalibrated optical method of monitoring variations
      in skin blood volume. The objective of the current study is to investigate a potential
      relationship between MRT (minimum rise time, in time units) a measure derived from PPG and
      the state of microvessels.

      This study includes a 1-2 hour single session per subject during which PPG and other
      microvascular and systemic variables will be monitored in response to non-invasive
      interventions that are known to elicit microvascular responses.
    

Detailed description: 
      Photoplethysmography (PPG) is a simple uncalibrated optical method of monitoring variations
      in skin blood volume. A major limitation of PPG is the lack of a quantitative method for
      calibrating this signal. A method that provides an absolute measure (in time units) called
      'minimum rise time' (MRT) was published in 1985 by Dr. Benjamin Gavish, one of the study
      investigators. However, a possible relationship between MRT and the state of arterioles that
      determines the microvascular flow has never been investigated. Such relationship, if
      validated, could have clinical impact in noninvasive diagnosis of vascular diseases and
      monitoring microvascular response to treatments that affect at both clinic and home setting.

      The objective of the current study is to investigate a potential relationship between
      variations of MRT (minimum rise time, in time units) and microcirculatory variables induced
      by interventions that are expected to have acute effect on the state of arterioles and the
      tissue oxygenation.

      This study includes a single 1-2 hour session per subject, during which PPG and other
      microvascular and systemic variables will be monitored in healthy volunteers in response to a
      number of non-invasive interventions/device that are approved for clinical use and known to
      elicit microvascular responses. These interventions are applied consecutively, include
      breathing at different rates, low power visible light in the red-to-near-infrared range, and
      local temperature changes. The experimental sessions will be conducted at the Afeka College
      by the study investigators.
    

Intervention name(s): RESPeRATE (Paced Breathing); Quantum Warp10 (Red LED); Omnilux new-U (Near Infrared LED); Heat/cold provocation
Intervention type(s): Device; Device; Device; Other
Intervention description(s): The subjects will be guided by a digital metronome to breath at 15, 10, and 6 breaths/min for 2 minutes each using the metronome function of the device RESPeRATE (InterCure, Israel) that guides breathing using musical tones played at selectable rhythm.; Immersion of one foot in a warm water bath ( 43-45 degrees C) for few seconds and then immersion of the same foot in cold water bath (5-7 degrees C) for 1 min.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Diagnostic