title: Method optimization on the use of postocclusive hyperemia model to assess microvascular function.
abstract: BACKGROUND
  Recent development had allowed non-invasive assessment of microvascular function in vivo; however, the method has not been fully optimized and standardized. In this study, we aimed to characterize the "effective" occlusion duration needed to elicit sufficient postocclusive hyperemia (PORH) responses in forearm skin using laser Doppler fluximetry (LDF), in subjects with differing age, gender and menstrual phases.
  
  
  METHODS
  A total of 120 healthy subjects were studied (20 subjects each in the age ranges of 21-30, 31-40, 41-50 for both genders). Male subjects were randomized to receive 1, 2 or 3 min occlusion on three study days. Females attended six study days: the first three days (with different occlusion times) were performed during low estrogenic phase of menstrual cycle and subsequent three visits were done during high estrogenic phase. Skin perfusion was measured before, during and after occlusion using LDF. The magnitude and temporal courses of PORH were expressed as PORH max (absolute maximal increase in hyperemia perfusion) and Tp (time-to-peak), respectively.
  
  
  RESULTS
  For PORH max analysis, the occlusion duration should be applied based on one's age, gender and menstrual phase. The PORH responses were more consistent during high estrogenic phase with 2 min found as the "effective" occlusion duration in all female groups. For Tp analysis, 3 min occlusion produced the significant change in all age ranges for both genders irrespective of menstrual phase.
  
  
  CONCLUSIONS
  This study revealed that for assessment of microvascular function using PORH+LDF model, the occlusion duration for PORH max is influenced by age, gender and menstrual phase. Measurement based on Tp is however independent of these factors.
authors.affiliation: Department of Biomedicine, School of Health Sciences, University Sains Malaysia, 16150 Kubang Kerian, Malaysia. yvonne@kb.usm.my
authors.forename: Get Bee
authors.initials: GB
authors.lastname: Yvonne-Tee
authors.forename: Aida Hanum Ghulam
authors.initials: AH
authors.lastname: Rasool
authors.forename: Ahmad Sukari
authors.initials: AS
authors.lastname: Halim
authors.forename: Abdul Rahim
authors.initials: AR
authors.lastname: Wong
authors.forename: Abdul Rashid Abdul
authors.initials: AR
authors.lastname: Rahman
mesh_terms: D000328:Adult; D000367:Age Factors; D004890:Erythema / Q000209:etiology; D004967:Estrogens / Q000378:metabolism; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000175:diagnosis* / Q000473:pathology*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D011693:Purpura / Q000209:etiology; D012107:Research Design; D012737:Sex Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D004967:Estrogens