title: Using reactive hyperemia to assess the efficacy of local cooling on reducing sacral skin ischemia under surface pressure in people with spinal cord injury: a preliminary report.
abstract: OBJECTIVE
  To investigate the efficacy of local cooling on reducing sacral skin ischemia in a weight-bearing position, and to identify the underlying physiological mechanisms using wavelet-based spectrum analysis of reactive hyperemia in people with spinal cord injury (SCI).
  
  
  METHODS
  Repeated-measures and before-after trial design.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Wheelchair users with SCI with injury level between C4 and T5 (n=10) and able-bodied controls (n=10).
  
  
  METHODS
  Three protocols consisting of pressure without temperature changes, pressure with local cooling (Δt=-10°C), and pressure with local heating (Δt=+10°C) were tested. Each protocol consisted of a 10-minute baseline period, a 20-minute loading period at 60 mmHg, and a 20-minute recovery period (reactive hyperemia). A 30-minute washout period was allowed between protocols.
  
  
  METHODS
  A compound sensor head consisting of laser Doppler and heating and cooling probes was used to measure sacral skin blood flow and control skin temperature. Reactive hyperemic response to pressure and temperature stimuli was characterized in the time and frequency (metabolic [.0095-.02 Hz], neurogenic [.02-.05 Hz], and myogenic [.05-.15 Hz] components) domains.
  
  
  RESULTS
  Pressure with local cooling resulted in a smaller reactive hyperemic response in both people with SCI and able-bodied controls as compared with pressure with local heating (P<.017) and pressure without temperature changes (P<.017), and the smaller hyperemia was attributed to reduced metabolic and neurogenic activities. People with SCI showed an attenuated response in reactive hyperemia (P<.017).
  
  
  CONCLUSIONS
  This study supports the concept of using local cooling to reduce skin ischemia under surface pressure in people with SCI.
authors.affiliation: Rehabilitation Research Laboratory, Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Champaign, IL. Electronic address: yjan@illinois.edu.
authors.forename: Yih-Kuen
authors.initials: YK
authors.lastname: Jan
authors.forename: Fuyuan
authors.initials: F
authors.lastname: Liao
authors.forename: Laura A
authors.initials: LA
authors.lastname: Rice
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Woods
mesh_terms: D000328:Adult; D003080:Cold Temperature; D005260:Female; D006358:Hot Temperature; D006801:Humans; D006940:Hyperemia / Q000517:prevention & control*; D007511:Ischemia / Q000517:prevention & control*; D008297:Male; D003668:Pressure Ulcer / Q000517:prevention & control; D012447:Sacrum; D012867:Skin / Q000098:blood supply; D012881:Skin Temperature; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D016474:Weight-Bearing; D014910:Wheelchairs
keywords: AB; BFO; Laser-Doppler flowmetry; Microcirculation; NS; Pressure ulcer; Rehabilitation; SCI; Skin temperature; Spinal cord injuries; Wavelet analysis; able-bodied; blood flow oscillation; not significant; spinal cord injury