title: [Changes in QT interval of electrocardiogram under +Gz acceleration and its significance].
abstract: OBJECTIVE
  To define whether QT interval could be used to predict the response of pilots to +Gz stress.
  
  
  METHODS
  37 pilots underwent +4 Gz acceleration on a human centrifuge. According to their responses to +Gz stress, subjects were divided into group A (good reaction group, n=18), group B (hyperfunction reaction group, n=14) and group C (inhibition reaction group, n=1). QT and RR interval were measured pre-, during and post-G. The data of 33 subjects (89.2%) whose QT interval could be measured were analyzed statistically.
  
  
  RESULTS
  During +Gz, QT and RR interval were shortened and sensitivity of QT interval to RR interval was augmented significantly (vs. pre-G, P<0.001); group B had higher sensitivity of QT interval to RR interval during +Gz (P<0.001, as compared with group A); discrimination functions established by QT and RR interval during +Gz were efficient and their accurate judgement rate was 81.8%.
  
  
  CONCLUSIONS
  The changes in QT interval of ECG were related to autonomic nervous imbalance under +Gz; QT interval and RR interval could be used to predict the response of pilots to +Gz stress. These suggested that the parameters and method in this study might be used in G-LOC warning system.
authors.affiliation: Institute of Space Medico-Engineering, Beijing, China.
authors.forename: B
authors.initials: B
authors.lastname: Wu
authors.forename: B S
authors.initials: BS
authors.lastname: Xie
authors.forename: Y Y
authors.initials: YY
authors.lastname: Xue
authors.forename: S Q
authors.initials: SQ
authors.lastname: Lu
authors.forename: G X
authors.initials: GX
authors.lastname: You
authors.forename: X H
authors.initials: XH
authors.lastname: Liu
mesh_terms: D000054:Acceleration; D000328:Adult; D000337:Aerospace Medicine; D001341:Autonomic Nervous System / Q000502:physiology; D002498:Centrifugation; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D018471:Hypergravity; D008297:Male; D011237:Predictive Value of Tests; D014474:Unconsciousness / Q000517:prevention & control