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[Changes in QT interval of electrocardiogram under +Gz acceleration and its significance]
Objective:
To define whether QT interval could be used to predict the response of pilots to +Gz stress.
Method:
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.
Result:
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%.
Conclusion:
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.