Investigator-initiated and industry-sponsored trials:
- Preparation of regulatory documents
- Database setup
- Physiological measurements
- Recruitment, study conduct and management, data analysis, reports
- Assessment of cerebral blood flow velocities
- Vascular reserve and pressure autoregulation
- Power M-Mode TCD technology (PMD-150), 2 channel, Spencer technologies Inc., Seattle WA
Autonomic Function Tests
- Autonomic, cardiovascular testing for syncope and falls
- Head-up tilt, exercise, Valsalva maneuver
- Multigas respiratory monitoring Capnomac Ultima
24-hour Portable Monitoring
- Portable beat-to-beat blood pressure monitoring ( Portapress)
- ECG, EMG, gait, activity monitoring (ME6000, Mega Elektronika, Inc)
- 24-hour ambulatory blood pressure monitoring (Dynapulse 5000 Auto, PulseMetric Inc )
- Activity monitoring
- Continuous glucose monitoring (CGM)
Gait and Balance
- Simultaneous recordings of gait kinematics, muscle activity, respiration and heart rhythms ( Noraxon DTS)
- Foot pressure distributions ( Pedar Mobile)
- Static posturography (Kistler Inc )
- Surface EMG (Bagnoli System)
- ME6000 ( Mega Elektronica, Inc) -wearable 16 channels system for monitoring ECG, EMG gait and activity up to 24 hours
- Software for gait and balance analysis using traditional measures, time series analysis-stabilogram diffusion analysis, multiscale entropy, etc.
Nonlinear Signal Processing
Methods for quantification of complex systems are available through collaboration with Dr. Goldberger and Dr. C.K. Peng ( Margret and H.A. Rey Institute for Nonlinear Dynamics at BIDMC/HMS).
- Hilbert-Huang Transform: Allows assessment of the often non-linear relationships between two acquired physiologic signals.
- Multimodal Pressure Flow Method (MMPF): The MMPF technique, based upon the Hilbert-Huang transform, measures coupling between two non-stationary signals. MMPF has been implemented to quantify cerebral autoregulation using the Valsalva maneuver and spontaneous pressure and flow oscillations. Cerebral autoregulation in healthy subjects can be characterized by large phase delays pressure and flow oscillations and its absence is an indicator of cerebrovascular disease. The MMPF technique has also been adapted to quantify the relationship between breathing and postural dynamics when standing.
- Synchronization Method: Phase synchronization analysis (5) allows exploration of the nonlinear interactions between complex oscillatory patterns.
- Multiscale Entropy (MSE): useful for the complexity analysis of a variety of physiologic time series such as heart beat time or force distribution series (6).
- Modified Wigner Distribution (WD): allows evaluation of short nonstationary data (7-10), i.e. EEG, heart rate, blood pressure, respiration, cerebral blood flow, and other pysiological signals.
- Stabilogram-diffusion Analysis: Postural control is assessed from the center of pressure (COP) displacements using traditional static measures and stabilogram-diffusion analysis that provides dynamics measures of COP fluctuations (11, 12). The COP signals behave as a positively correlated random walk over short-time scales characterized by a Hurst exponent (13).
Registration and segmentation of 3 Tesla MP-RAGE and FLAIR images are used to quantify global and regional brain and white matter hyperintensities volumes. Diffusion tensor imaging is used to assess white matter integrity and connectivity.
Cerebral blood flow and vasoreactivity assessment
Noninvasive brain perfusion measurements are made using 3D Continuous Arterial Spin Labeling (CASL) at 3Tesla. In collaboration with Dr. Alsop and the Center for Advanced Magnetic Resonance Imaging, BIDMC, we have applied these techniques to study 1) the measurement of cerebral blood flow and its distribution, 2) vasoreactivity in vascular territories, and 3) quantitative vascular reactivity and its distribution, in aging and disease.
The SAFE lab databases include data acquired from physiological studies in people > 50 years old who are healthy, or suffer from chronic conditions of type 2 diabetes, hypertension and/or stroke. Data includes:
- Cardiovascular and cerebral blood flow measurements during head-up tilt, standing, and walking
- Gait and balance measurements with cardiovascular parameters
- Anatomical and perfusion MRIs of the brain at 3 Tesla
- 24 hour ECG, blood pressure, EMG, continuous glucose and activity measurements
The Safe Lab is set for simultaneous studies of gait, balance, autonomic, cardiovascular, and respiratory systems, electromyography and cerebral and peripheral blood flow. These tests allow functional assessment of multiple organ systems and interactions among them. methods of nonlinear analysis enable to study dynamics of complex interactions among physiological signals. Magnetic resonance imaging is used to study brain anatomy and cerebral blood flow and its regulation.