M-3动作时颈内动脉血流动力学的变化

目的探讨Ｍ－３动作对颈内动脉血流动力学的影响及意义。方法应用彩色多普勒血流显像测量了３２名飞行员在＋１ＧＺ条件下实施Ｍ－３动作时颈内动脉收缩期峰１流速（ＶＳ１）、收缩期峰２流速（ＶＳ２）、舒张期峰流速（ＶＤ）、舒张末期速度（Ｖｄ）、平均血流速度（Ｖｍ）、脑血流量（ＣＢＦ）、心率（ＨＲ）、阻力指数（ＲＩ）和搏动指数（ＰＩ）等参数。结果ＶＳ２、ＶＤ、Ｖｍ和ＣＢＦ较平静时分别提高２３％、３１％、２４％和２５％，ＲＩ和ＰＩ分别降低８％和２４％。Ｖｍ与ＣＢＦ相关性好（ｒ＝０．７２，Ｐ＜０．０１）。ＶＳ１、Ｖｄ和ＨＲ与平静时比较无显著差异（Ｐ＞０．０５）。结论Ｍ－３动作主要影响并增大ＶＳ２、ＶＤ和Ｖｍ，降低脑血管阻力，维持脑供血。

Changes of internal carotid hemodynamics during M 3 maneuver

Objective To study the effect of M 3 maneuver on internal carotid artery hemodynamics and its significance. Mehods Thirty two pilots served as subjects. Color doppler flow imaging (CDFI) was used to measure their systolic peak 1 flow velocity (V S 1), systolic peak 2 flow velocity (V S 2), diastolic peak flow velocity (V D), enddiastolic velocity (V d), mean flow velocity (V m), cerebral blood flow (CBF), heart rate (HR), resistance index (RI) and pulsatility index (PI) during rest and M 3 maneuver in 1 G condition. Results The values of V S 2, V D, V m and CBF during M 3 maneuver increased by 23%, 31%, 24%, and 25% respectively as compared with those in rest condition, while RI and PI decreased by 8% and 24%, respectively. There was a positive correlation between Vm and CBF ( r=0.72, P< 0.01). The changes of V S 1, V d and HR as compared with those in rest condition was non significant ( P >0.05). Conclusion The major effect of M 3 maneuver was increase of V S 2, V D and V m, as well as lowering of cerebral vascular resistance, so that cerebral blood supply can be effectively maintained.