[Features of heart rate, blood pressure, heart rate variability and cerebral blood flow during sequential head-up tilt test].
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.
Wu
Liu-xin
LX
Institute of Aviation Medicine, Beijing, China.
Qiang
Dong-chang
DC
Song
Lei
L
Shi
Lu-jiang
LJ
Zheng
Xue-wei
XW
Jiao
Zhi-gang
ZG
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