平静呼吸对肺静脉血流的影响及其机制的超声心动图研究

Study of effects of quiet respiration on pulmonary venous flow and the mechanism by Doppler echocardiography

目的研究平静呼吸对肺静脉血流的影响及其规律,进一步验证呼吸影响心功能机制新假说,探讨肺静脉血流速度随呼吸变化对评价左心室舒张功能潜在的意义。方法20名健康志愿者,采用Sequoia512超声仪,同步记录右上肺静脉血流速度频谱、心电图和呼吸曲线。连续测量5个呼吸周期吸气相和呼气相血流速度及速度时间积分(VTI),取平均值。分别计算吸气相和呼气相肺静脉收缩期S波与舒张期D波的速度比值以及VTI比值。结果肺静脉收缩期S波血流速度及VTI于吸气相和呼气相之间变化不显著(P=0.221;P=0.090);舒张期D波血流速度及VTI在吸气相低于呼气相(均P<0.001);S波与D波血流速度比值及VTI比值在吸气相高于呼气相(均P<0.001)。结论平静呼吸对肺静脉血流影响具有规律性S波血流速度及VTI于吸气相和呼气相之间变化不显著;D波血流速度及VTI在吸气相低于呼气相;S波与D波血流速度比值及VTI比值在吸气相高于呼气相,其中血流速度比值在吸气相>1,而在呼气相可>1,也可≤1。进一步验证了呼吸影响心功能机制新假说。利用肺静脉频谱评价左室舒张功能时如能结合呼吸的影响则可能提供更多信息。

Objective To observe the effects of quiet respiration on pulmonary venous flow and its regularity, and to verify the new proposal of the mechanism of respiration effects on hemodynamics. Methods Pulsed-wave Doppler spectra of right-upper pulmonary vein were recorded with Sequoia 512 in 20 normal subjects. Electrocardiogram and respiratory tracing were recorded simultaneously. S wave and D wave of pulmonary venous velocity were traced and the velocity-time integrals（VTI） were calculated by the software. The pulmonary venous velocity and VTI during inspiration and expiration were averaged for five respiratory cycles separately. The ratios of velocity and VTI of S wave to D wave of pulmonary vein during inspiration and expiration were calculated separately. Results The velocity and VTI of S wave of pulmonary venous flow did not vary dramatically between inspiration and expiration [（58.31 ± 9.22）cm/s vs （58.96± 7.79）cm/s, P = 0. 221; （16.29 ± 2. 59）cm vs （16.54 ± 2.18）cm, P = 0. 090];the velocity and VTI of D wave of pulmonary venous flow increased remarkably from inspiration to expiration [（48.23 ± 8.32） cm/s vs （51.82 ± 8. 72）cm/s, P 〈0. 001 ; （10.84 ± 1.65）cm vs （11.66 ± 1.53）cm, P 〈0. 001 ] ;while the ratios of the velocity and VTI of S wave to D wave significantly decreased from inspiration to expiration （1.23±0.22 vs 1.17±0.27, P〈0.001;1.53±0.31 vs 1.43±0.22, P〈0.001）. Conclusions Theblood flow velocity and VTI of S wave did not vary dramatically between inspiration and expiration; the blood flow velocity and VTI of D wave were lower during inspiration than those during expiration; while the ratios of the velocity and VTI of S wave to D wave were higher during inspiration than those during expiration. The study also proved the accuracy of the new proposal of the mechanism of respiration effects on hemodynamics.