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目的了解心脏前负荷减低对中心动脉压及主动脉扩增指数的影响。方法10例健康志愿者,行下肢负压(LB-NP)抽吸造成不同程度前负荷减低。采用超声心动图检测心输出量的变化;采用中心动脉压力分析系统(SphymoCor)检测桡动脉压力波形,经平均转换功能形成中心动脉压力波形。结果①随着下肢负压的加大,上腔静脉血流进行性减低,在-30mmHg阶段,S波减低22.4%,VTIs+d减低了15.8%,同时SV减少24.7%,CO减少18.7%;②中心动脉收缩压(CSBP)除在-30mmHg阶段轻度下降外,在-10及-20mmHg阶段没有明显改变,中心动脉舒张压(CDBP)在各个负压阶段没有明显改变;③主动脉压力波P1在各个负压阶段均明显下降,在-30mmHg阶段,P1减少了19.6%[(28.2±5.02)mmHgvs.(22.65±3.08)mmHg,P<0.01],而总外周阻力(TPR)在各负压阶段均较基础阶段明显升高,在-30mmHg阶段升高21.3%[(16.0±2.9)(mmHg.min)/Lvs.(20.3±3.4)(mmHg.min)/L,P<0.001]。主动脉扩增指数(AI)无明显改变。结论前负荷减低使中心主动脉压及主动脉压力波P1降低,同时使TPR升高,由于TPR的升高抵消了P1的降低,因而AI保持不变。
Objective To investigate the influence of pre-cardiac load reduction on central arterial pressure and aortic expansion index. Methods Ten healthy volunteers underwent lower extremity negative pressure (LB-NP) aspiration, resulting in different degrees of preload reduction. The changes of cardiac output were detected by echocardiography. The radial artery pressure waveform was detected by SphymoCor and the mean arterial pressure waveform was formed by the average conversion function. Results With the increase of the negative pressure of the lower extremity, the superior vena cava blood flow decreased progressively. In the -30 mmHg stage, S wave decreased by 22.4%, VTIs + d decreased by 15.8%, SV decreased by 24.7% and CO decreased by 18.7%. ② The central artery systolic blood pressure (CSBP) did not change significantly at -10 and -20 mmHg, except for mild decrease at -30 mmHg stage. The central artery diastolic blood pressure (CDBP) did not change significantly during each negative pressure stage. ③ The aortic pressure wave P1 decreased significantly at all negative pressure stages, P1 decreased by 19.6% at -30 mmHg [(28.2 ± 5.02) mmHg vs (22.65 ± 3.08) mmHg, P <0.01], while total peripheral resistance (TPR) Pressure stage was significantly higher than the basic stage, in the -30mmHg stage increased by 21.3% [(16.0 ± 2.9) mmHg.min / Lvs. 20.3 ± 3.4 mmHg.min / L, P 0.001]. Aortic expansion index (AI) no significant change. Conclusions The decrease of anterior load leads to decrease of central aortic pressure and aortic pressure wave P1, and increase of TPR at the same time. As the increase of TPR counteracts the decrease of P1, AI remains unchanged.