title: Evaluation of a new high power, wide separation laser Doppler probe: potential measurement of deeper tissue blood flow.
abstract: OBJECTIVE
  To compare the output from a novel high power, wide separation laser Doppler flow probe (DP1-V2-HP, 4 mm, with IRLD20) with that of a standard flow probe (DP1-V2, 0.5 mm, with DRT4) (Moor UK) and to explore its potential for use in the noninvasive measurement of blood flow in deeper tissues in humans.
  
  
  METHODS
  Monte Carlo modeling was used to predict depths of light scattering in skin with each probe, geometry. Experimentally, forearm blood flow was measured at rest and during local warming of the skin surface and post occlusion reactive hyperaemia (PORH). Laser Doppler blood flux (LDF) and the power spectral density of its component frequency intervals, were compared.
  
  
  RESULTS
  Monte Carlo modeling indicated that while the majority of wide probe LD signal derives from deeper tissue, a significant portion is from superficial (dermal) tissue (and vice versa for standard probe). Perturbation of local blood flow differentially increased LDF and spectral power as measured by the two probes, with the standard skin probe showing a significantly greater response to local skin warming (p<0.01).
  
  
  CONCLUSIONS
  These differences support our hypothesis that the wide probe is recording predominantly blood flux within the vasculature of sub-dermal tissue. This is in agreement with Monte Carlo simulation.
authors.affiliation: Institute of Developmental Sciences, School of Medicine, University of Southampton, UK. g.f.clough@soton.ac.uk
authors.forename: Geraldine
authors.initials: G
authors.lastname: Clough
authors.forename: Andrew
authors.initials: A
authors.lastname: Chipperfield
authors.forename: Christopher
authors.initials: C
authors.lastname: Byrne
authors.forename: Frits
authors.initials: F
authors.lastname: de Mul
authors.forename: Rodney
authors.initials: R
authors.lastname: Gush
mesh_terms: D000328:Adult; D019540:Area Under Curve; D003198:Computer Simulation; D004867:Equipment Design / Q000295:instrumentation*; D005069:Evaluation Studies as Topic; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation* / Q000592:standards; D035002:Lower Extremity / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D055095:Optics and Photonics; D012039:Regional Blood Flow / Q000502:physiology*; D012867:Skin / Q000098:blood supply*; D013997:Time Factors