有晕厥史飞行员立位应激下自主神经功能评价

目的：评价加速度引起的意识丧失（G－LOC）或血管迷走性晕厥（VVS）飞行员在立位耐力试验（OTT）条件下自主遥作用。方法：对30例晕厥并阳 性OTT病例组（I组），20例晕厥并阴性OTT病例组（Ⅱ组）和15例年龄，性别，飞行机种，飞行时间相匹配的健康飞行员（对照组）的心率变异（HRV）和OTT的关系进行研究，对所测量OTT前后心率（HR），收缩压（SBP），舒张压（DBP）和HRV指标进行对比分析。结果：3组被试者OTT前平均HR，SBP，DBP比较无显著性差异（P＞0．05），OTT后I组HR明显高于其他两组（P＜0．01），SBP和DBP明显低于其他两组（P＜0．01），HRV指标中I组24h连续RR间期标准差（SDNN），HRV三角指数（HRVI），RR间期平均值（RR）明显小于其他两组（P＜0．01），平均1h 功率谱分析I组低频成分／高频成份比值（LF／HF）明显高于其他两组（P＜0．05），结论：晕厥并阳性OTT飞行员立位应激下交感神经张力增强，副交感神经张力减弱，使自主神经功能失调。

Assessment of Autonomic Nervous Function during Orthostatic Stress in Pilots with History of Syncope

Objective To assess the role of autonomic nervous function during orthostatic tolerance tests (OTT) in pilots with history of G induced loss of consciousness (G LOC) or vasovagal syncope (VVS). Method The relation between heart rate variability (HRV) and outcome of OTT result were compared among 3 groups of cases:1) 30 patients with history of syncope and positive OTT as patient group (PG);2) 20 cases with history of syncope but negative OTT result as negative group (NG); 3) 15 age , sex ,flight plane model ,flight time matched healthy pilots as healthy control (HC). OTT results and HRV,heart rate (HR), systolic blood pressure (SBP),and diastolic blood pressure (DBP) before and after OTT and their time and frequency domain were compared and analyzed among the three groups. Result HR,SBP,and DBP were not significantly different (P>0.05) among the three groups before OTT. But during OTT,HR in PG was higher than those in NG and HC (P<0.01),SBP and DBP in PG were lower than those in NG and HC (P<0.01). 24 h continuous RR interval standard difference (SDNN),HRV triangle index (HRVI),and interval average value in PG were significantly lower than those in NG and HC;Power spectrum analysis of mean 1 h value for low frequency part (LF) and high frequency part (HF) were not significantly different among three groups,but LF/HF ratio in PG was higher than that in NG or HC (P<0.05). Conclusion It is suggested that G LOC and VVS may be due to increase in sympathetic tone and decrease in parasympathetic tone during orthostatic stimulation,as resulted from autonomic nervous dysfunction.