title: Dynamics of microvascular blood flow and oxygenation measured simultaneously in human skin.
abstract: OBJECTIVE
  To evaluate the dynamics of skin microvascular blood flow (BF) and tissue oxygenation parameters (OXY) measured simultaneously at the same site using a combined non-invasive BF+OXY+temperature probe.
  
  
  METHODS
  Skin BF, oxygenated (oxyHb) and deoxygenated (deoxyHb) haemoglobin and mean oxygen saturation (SO2 ) were measured in 50 healthy volunteers at rest and during perturbation of local blood flow by post-occlusive reactive hyperaemia, sympathetic nervous system-mediated vasoconstriction (deep inspiratory breath-hold) and local skin warming. Signals were analysed in time and frequency domains.
  
  
  RESULTS
  The relationship between BF and SO2 over the range of flows investigated was described by a non-linear equation with an asymptote for SO2 of 84% at BF >50 PU. SO2 was independently associated with BF, skin temperature, BMI and age, which together identified 59% of the variance in SO2 (p<0.0001). Fourier analysis revealed periodic low frequency fluctuations in both BF and SO2 , attributable to endothelial (~0.01 Hz), neurogenic (~0.04 Hz) and myogenic (~0.1 Hz) flow motion activity. The frequency coherence between the BF and SO2 signals was greatest in the endothelial and neurogenic frequency bands.
  
  
  CONCLUSIONS
  The simultaneous evaluation of microvascular blood flow and oxygenation kinetics in healthy skin provides a platform from which to investigate microvascular impairment in the skin and more generally the pathogenesis of microvascular disease.
authors.affiliation: Human Development & Health, Faculty of Medicine, University of Southampton, Southampton, UK.
authors.forename: Katarzyna Z
authors.initials: KZ
authors.lastname: Kuliga
authors.forename: Erin F
authors.initials: EF
authors.lastname: McDonald
authors.forename: Rodney
authors.initials: R
authors.lastname: Gush
authors.forename: Charles
authors.initials: C
authors.lastname: Michel
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Chipperfield
authors.forename: Geraldine F
authors.initials: GF
authors.lastname: Clough
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D055806:Microvessels / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D012867:Skin / Q000098:blood supply*; D014661:Vasoconstriction / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: endothelial function; flow motion; laser Doppler flowmetry; microcirculation; skin; tissue oxygenation; white light spectrometry