Hemodynamic Responses Induced by 75° and 60° Head-up Tilt

Liu Jiexin; Yuan Ming; Wang Linjie; Li Yongzhi; Bart Verheydn; Du Song; Zhao Xingquan; Qu Lina; Li Zhili; Chen Zhanghang; Wu Yueyang; Yang Xiaomeng; Li Zhaoxia; André Aubert; Li Yinghui

doi:10.16289/j.cnki.1002-0837.2020.05.001

Abstract：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.