UTLight-transcranial Doppler Assessment of Regional Cerebral Autoregulation
Condition: Diabetes
Study type: Observational

Summary: 
      Cerebral autoregulation (CA) is a complex mechanism that serves the essential and vital
      purpose of controlling cerebral blood flow and metabolism. A stable and optimal brain blood
      flow is imperative for normal brain function. Diabetes Mellitus (DM ) is associated with
      microvascular disease that alters CA and also with autonomic failure that may lead to
      orthostatic hypotension (OH). These conditions may lead to decreased brain blood flow in
      upright position. This observational study will compare two technologies that evaluate brain
      blood flow during standing up and other maneuvers in people with and without type 2 diabetes.
      These technologies are transcranial Doppler and UTLight technology (CerOx). This study will
      determine the safety and feasibility of CerOx technology for continuous monitoring of
      cerebral blood flow.
    

Detailed description: 
      Cerebral autoregulation (CA) is a complex mechanism that serves the essential and vital
      purpose of controlling cerebral blood flow and metabolism. A stable and optimal brain blood
      flow is imperative for normal brain function; therefore normal function of CA is crucial for
      brain health. Diabetes mellitus (DM) is associated with microvascular disease and abnormal
      autoregulation, which increases risk for stroke and death. Failure of CA has serious
      consequences across the lifespan and, in terms of prevalence adverse outcomes related to
      failing CA are most prominent in the elderly with diabetes.

      Older diabetic adults often suffer from hypotension or fainting upon standing-up and may have
      abnormal CA. With abnormal CA, cerebral perfusion and tissue oxygenation declines upon
      standing up. Abnormalities in perfusion regulation in older people, and particularly those
      with diabetes may accelerate progression of brain atrophy resulting in cognitive decline,
      vascular dementia or Alzheimer's disease.

      UTLight technology (CerOx), provides a new tool for evaluation of regional blood flow and
      oxygenation in cortical microvasculature, which is lacking in clinical medicine and patient
      care. UTLight may become a novel tool that would provide an easy and reliable assessment of
      regional perfusion and CA in specific cortical areas in health and disease that can be widely
      implemented in outpatient clinics. This is a pilot, observational feasibility study to
      compare blood flow measurements using UTLight and TCD.

      Aim 1: To assess the safety and feasibility of UTLight for evaluation of regional cerebral
      blood flow regulation in the anterior circulation ((ACA) and/or middle cerebral artery (MCA)
      territories) in 20 non-diabetic adults >50 yrs old and 40 age-matched adults with type 2
      diabetes.

      Aim 2: To compare the profiles of UTLight blood flow (UT_BF), regional oximetry (UT_Ox) and
      TCD-blood flow velocities (TCD_BFV) in response to: 1) blood pressure changes induced by the
      postural change from supine to head-up tilt, and from sitting to standing-up; and 2)
      vasodilatation and vasoconstriction responses induced by hypercapnia and hypocapnia.

      The investigators hypothesize that:

        1. UT_BF will accurately track TCD_BFV in responses in the anterior circulation (ACA and/or
           MCA territory) to blood pressure changes, hypercapnia and hypocapnia challenges in
           healthy older people.

        2. UT_BF may be more sensitive to detect abnormalities in regional perfusion in diabetic
           adults as compared to healthy controls and compared to TCD_BFV.

      (UT_Ox) may provide a new indicator to identify older diabetic adults with brain tissue
      hypoxia during orthostatic challenges that may be at greater risk of brain damage of
      cognitive decline that will be derived from a change in tissue oxygenation upon standing up
      that is not routinely evaluated by TCD. Outcomes: Primary outcome is the sensitivity and
      specificity of UT_BF and TCD_BFV to blood pressure and CO2 challenges, defined as percent
      change of UT_BF and TCD_BFV in response to hypercapnia and hypocapnia challenges. Secondary
      outcomes are the differences in cerebral blood flow measured by UT_BF, TCD_BFV between
      healthy old and diabetic subjects during postural changes. Third outcomes are differences in
      UT_Ox between healthy old and diabetic subjects.
    

Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Population sample
      
Keywords: cerebral blood flow; near infrared spectroscopy; transcranial Doppler; diabetes mellitus; cerebral autoregulation