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目的 研究适当增加倾斜角度的头高位倾斜试验能否在缩短测试时间的同时,产生与传统低角度倾斜试验方案类似的血流动力学效应.方法 22名志愿者参与实验,均先后采用2种不同的无药物诱发倾斜测试方案.首先进行60°标准方案(60SP组)实施倾斜测试45 min,14天后,第2次倾斜试验采用75°短时方案(75SD组)测试20 min.两次倾斜测试中全程采用红外指端体积描记法进行无创逐搏血压监测,并分析心率(HR)、血压、每搏量(SV)、心输出量(CO)、系统血管阻力(SVR)和压力反射敏感性(BRS).结果 在立位前的平卧位,2种测试方案中志愿者心率、血压、每搏量、心输出量、系统血管阻力和压力反射敏感性无显著差异.在立位的初始反应阶段,2种测试方案中血流动力学参数改变也无显著差异.在头高位的进展阶段,60SP组的45 min和75SD组的20 min时,志愿者所有血流动力学参数中只有每搏量存在显著性差异(P=0.01).结论 更高角度及更短时程的倾斜实验方案中,绝大多数血流动力反应与传统低倾斜角度长时程倾斜测试方案诱发的效应一致.更高角度及更短时程的倾斜测试方案能够在类似效率的基础上节约临床诊断时间.“,”Objective To study whether the head-up tilt test(HUTT) with an appropriate increased tilt angle can produce similar hemodynamic effects during shortened tilt duration with the effects of traditional lower angle tilt protocol.Methods Twenty-two healthy volunteers participated in this study.Two different drug-free tilt test protocols were used.First,tilt test was performed with the 60° standard protocol (60SP group) for 45 min,after 14 days,the second tilt test was performed with the 75° short duration protocol for 20 min (75SD group).Noninvasive beat-to-beat blood pressure was measured with an infrared finger photoplethysmograph during the two tilt test protocols,while heart rate (HR),blood pressure,stroke volume(SV),cardiac output(CO),systemic vascular resistance(SVR) and baroreflex sensitivity(BRS) were estimated.Results No significant difference was found in HR,MAP,SV,CO,SVR and BRS between the two tilt tests with different protocols in the supine position before tilt.No significant hemodynamic change was found in the initial responses to the two different tilt angles.In the evolution of up-right position,only a significant difference could be found in SV (P=0.01) between 60SP for 45 min and 75SD for 20 min around all hemodynamic parameters.Conclusion It is suggested that most hemodynamic responses to higher tilt angle with shorten time duration are equal to the effects of traditional lower tilt angle with longer time duration.The tilt test protocol with higher angle and shorten time duration will save the diagnostic time for clinical application with the similar effectiveness.