An Exploratory Study On The Factors Affecting The Peak Response Time Of The Left Ventricular Outflow Tract Velocity Time Integral Variation Rate Caused By The Passive Leg Lift Test

Background VTI variations(△VTI)combined with passive leg raising(PLR)test is one of the methods to predict volume responsiveness.However,in current studies,there is no description of the timing of the appearance of the peak AVTI(△VTImax)in different kinds of patients.This study is intended to explore the timing of the △VTImax during PLR,and the influenced factors.Methods It is a prospective study,included 48 patients who met the research criteria,recorded the basic information,cardiac function assessment,and PLR test was done and a 250 seconds of VTI recording.Results There was no statistical difference between the mean arterial pressure and heart rate changes in patients before and after PLR(P=0.39;P=0.15).For 4 minutes after PLR,take 30 seconds as a period,△VTImax appears in each time period.In all 48 patients,only 45.8%patients showed △VTImax within 2min,but a slightly higher proportion in VR group(57.69%).Seventeen patients(65.38%)had a △VTI>12%in the VR group before its △VTImax in 4 minutes after the PLR test.Defined by the first △VTI>12,24 patients(92.3%)was affirmed VR within 2 min after PLR.Six patients(23.07%)were misjudged as NVR if the measurement of AVTI>12 was began from 2min after PLR test.There was no significant correlation between four echocardiography indexes(including LVEF and EPSS,E/A,TAPSE,VTIO)and the time of AVTImax in PLR test(p>0.05).The variation of △VTI was negatively correlated with the cardiac systolic function index(LVEF r=-0.633,and TAPSE r=0.457,both p<0.01).Conclusion When the left ventricular outflow channel △VTI is used to determine the VR of PLR test patients,it is recommended to monitor continuously,from the beginning time of PLR test to at least 2 min.There is no significant difference in the monitoring time of△VTImax between the mechanical ventilation and the spontaneous breathing patients when PLR.Cardiac function was not correlated with the appearance time of △VTImax in PLR test patients.There was a negative correlation between cardiac systolic function and△VTI change range.Objective To investigate the use of point-of-care ultrasound(POCUS)and the knowledge mastered of ultrasound in mainland emergency physicians.Methods From September 2018 to December 2018,used the Research Electronic Data Capture(REDCAP)website editor to generate a questionnaire link and release the questionnaires by WeChat.Results A total of 2802 physicians read the questionnaire connection,776 of them filled out the questionnaire,delete the repeat answer and invalid questionnaire(missing or blank)94 copies,recycling 682 effectively response.The recycling of questionnaires was from every administrative divisions throughout the country and all kinds of hospitals.Five hundred and seventy(83.5%)physicians come from third level hospitals,110(16.2%)physicians from the second level hospitals,only 2(0.3%)physicians from the first level hospitals.Two hundred and forty-one(35.4%)physicians in the investigation had not heard or practiced POCUS.The proportion processes and commonly used of POCUS in emergency departments is between 1/3 and 2/3(31.5%-68.3%).The accuracy of the six questions of ultrasonic theory is between 44.1%and 68.7%,less than a half(49.3%)of the respondents had chosen all the correct answer of the six issues.There was a significant difference in the accuracy between the POCUS trained and non-trained physicians(p<0.05),the reading of ultrasound books or literature,daily use POCUS,or participation in POCUS training were positively correlated with the accuracy of the six questions(P<0.01,P<0.01 and P=0.034).Conclusion The degree of popularization of POCUS in emergency department in China needs to be developed urgently.