title: [Features of heart rate, blood pressure, heart rate variability and cerebral blood flow during sequential head-up tilt test].
abstract: OBJECTIVE
  To investigate the features of BP, HR, cerebral blood flow (CBF) and heart rate variation (HRV) during sequential head-up tilt table test (HUT) and provide information for methodology of testing tendency to syncope in pilots.
  
  
  METHODS
  Sixteen healthy male were exposed to HUT +45 degrees 20 min, +60 degrees 20 min, and +75 degrees 20 min respectively with 5 min rests in between. CBFV, HR, HRV, BP were measured with transcranial doppler image (TCI), 12-Lead in phase ECG.
  
  
  RESULTS
  1) As the tilt angle became larger, HR and DBP increased gradually (P<0.05), with SBP, PP and CBF Velocity (Vs,Vm,Vd) descended. There were significant differences among the various conditions. CV became smaller before +75 degrees, and then it began to increase. 2) Correlation between physiological indices and techno-indices were analyzed. At the point of 1 min, tilt angle was significantly positively correlated with SBP, DBP, MAP, Vd, and sdRR (P<0.01); At the point of 20 min, tilt angle was significantly positively correlated with HR and sdRR (P<0.01), but negatively correlated with SBP, PP, Vs and mRR (P<0.01), time of exposure was positively correlated with HP (P< 0.01), but negatively correlated with Vm, Vd, and mRR (P<0.01). 3) Correlation among physiological indices were also analyzed. HR were negatively correlated with SBP, Vs, Vm and Vd (P<0.01), SBP were significantly positively correlated with Vd, and mRR (P<0.01). Vs, Vm, Vd were significantly positively correlated with mRR and sdRR (P< 0.01).
  
  
  CONCLUSIONS
  By investigating HR, BP, HRV and CBFV during of different angles, some advises for evaluating the tendency to syncope in pilots were put forward.
authors.affiliation: Institute of Aviation Medicine, Beijing, China.
authors.forename: Liu-xin
authors.initials: LX
authors.lastname: Wu
authors.forename: Dong-chang
authors.initials: DC
authors.lastname: Qiang
authors.forename: Lei
authors.initials: L
authors.lastname: Song
authors.forename: Lu-jiang
authors.initials: LJ
authors.lastname: Shi
authors.forename: Xue-wei
authors.initials: XW
authors.lastname: Zheng
authors.forename: Zhi-gang
authors.initials: ZG
authors.lastname: Jiao
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D001794:Blood Pressure / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004198:Disease Susceptibility; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology*; D013575:Syncope / Q000209:etiology / Q000503:physiopathology*; D018667:Tilt-Table Test