title: Reduced speed of microvascular blood flow in hemodialysis patients versus healthy controls: a coherent hemodynamics spectroscopy study.
abstract: We present a pilot clinical application of coherent hemodynamics spectroscopy (CHS), a technique to investigate cerebral hemodynamics at the microcirculatory level. CHS relies on frequency-resolved measurements of induced cerebral hemodynamic oscillations that are measured with near-infrared spectroscopy (NIRS) and analyzed with a hemodynamic model. We have used cyclic inflation (200 mmHg) and deflation of a pneumatic cuff placed around the subject's thigh at seven frequencies in the range of 0.03 to 0.17 Hz to generate CHS spectra and to obtain a set of physiological parameters that include the blood transit times in the cerebral microcirculation, the cutoff frequency for cerebral autoregulation, and blood volume ratios across the three different compartments. We have investigated five hemodialysis patients, during the hemodialysis procedure, and six healthy subjects. We have found that the blood transit time in the cerebral microcirculation is significantly longer in hemodialysis patients with respect to healthy subjects. No significant differences were observed between the two groups in terms of autoregulation efficiency and blood volume ratios. The demonstration of the applicability of CHS in a clinical setting and its sensitivity to the highly important cerebral microcirculation may open up new opportunities for NIRS applications in research and in medical diagnostics and monitoring.
authors: Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155.
authors: Michele L
authors: ML
authors: Pierro
authors: Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155.
authors: Jana M
authors: JM
authors: Kainerstorfer
authors: Tufts Medical Center, 800 Washington Street, Boston, Massachusetts 02111.
authors: Amanda
authors: A
authors: Civiletto
authors: Tufts Medical Center, 800 Washington Street, Boston, Massachusetts 02111.
authors: Daniel E
authors: DE
authors: Weiner
authors: Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155.
authors: Angelo
authors: A
authors: Sassaroli
authors: Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155.
authors: Bertan
authors: B
authors: Hallacoglu
authors: Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155.
authors: Sergio
authors: S
authors: Fantini
mesh_terms: D000328:Adult; D000465:Algorithms; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006706:Homeostasis; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D010865:Pilot Projects; D006435:Renal Dialysis; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult