title: Adaptive feedback analysis and control of programmable stimuli for assessment of cerebrovascular function.
abstract: The assessment of cerebrovascular regulatory mechanisms often requires flexibly controlled and precisely timed changes in arterial blood pressure (ABP) and/or inspired CO₂. In this study, a new system for inducing variations in mean ABP was designed, implemented and tested using programmable sequences and programmable controls to induce pressure changes through bilateral thigh cuffs. The system is also integrated with a computer-controlled switch to select air or a CO₂/air mixture to be provided via a face mask. Adaptive feedback control of a pressure generator was required to meet stringent specifications for fast changes, and accuracy in timing and pressure levels applied by the thigh cuffs. The implemented system consists of a PC-based signal analysis/control unit, a pressure control unit and a CO₂/air control unit. Initial evaluations were carried out to compare the cuff pressure control performances between adaptive and non-adaptive control configurations. Results show that the adaptive control method can reduce the mean error in sustaining target pressure by 99.57 % and reduce the transient time in pressure increases by 45.21 %. The system has proven a highly effective tool in ongoing research on brain blood flow control.
authors: Department of Medical Physics, University Hospitals of Leicester NHS Trust, Infirmary Square, Leicester LE1 5WW, UK. lingke.fan@le.ac.uk
authors: Lingke
authors: L
authors: Fan
authors: Glen
authors: G
authors: Bush
authors: Emmanuel
authors: E
authors: Katsogridakis
authors: David M
authors: DM
authors: Simpson
authors: Robert
authors: R
authors: Allen
authors: John
authors: J
authors: Potter
authors: Anthony A
authors: AA
authors: Birch
authors: Ronney B
authors: RB
authors: Panerai
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004867:Equipment Design; D005246:Feedback; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013848:Thigh / Q000098:blood supply
chemical_list: D002245:Carbon Dioxide
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