The ultrasonic monitoring coupled with passive leg raising test for evaluation of fluid responsiveness in critical patients

Objective To explore the value of predicting fluid responsiveness using velocity time index variation (ΔVTI) and stroke volume variation (ΔSV) before and after passive leg raising (PLR) monitored by bedside temporary test equipment (TTE). Methods A cohort of 42 patients supported with mechanical ventilation in our hospital admitted from October 2014 to October 2015 were prospectively selected. The hemodynamic variables including heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), VTI, SV and other parameters were monitored before and after after undergoing PLR. Fluid resuscitation volume expansion test was carried out after stroke volume index (SVI) monitored by pulse indicator continuous cardiac output monitoring (PICCO). Patients were divided into fluid responsiveness positive group and fluid responsiveness negative group according to presence or absence of SVI ≥ 15% after fluid resuscitation volume expansion. Results Of 42 patients, 22 belonged to fluid responsiveness positive group, 20 got into fluid responsiveness negative group. There were no significant differences in basic clinical data between two groups. Before and after PLR, there were no distinct changes in HR and CVP(P>0.05), while MAP, VTI and SV increased significantly(P 0.05), but HR, CVP and VTI increased significantly(P<0.05) in fluid responsiveness negative group. The degrees of ΔVTI and ΔSV in fluid responsiveness positive group were much higher than those in fluid responsiveness negative group (P<0.05). According to SVI ≥ 15% monitored by PICCO after fluid resuscitation volume expansion test as a standard, the area under the ROC (AUC) of ΔVTI between pre-PLR and post-PLR was 0.75 (95%CI: 0.593-0.907, P<0.01), the sensitivity and specificity were 63.6% and 95% respectively using ΔVTI 15.6% as threshold value. The AUC of ΔSV was 0.844 (95%CI: 0.716-0.972, P<0.01), the sensitivity and specificity were 81.8% and 85.0% respectively using ΔSV 10.5% as threshold value. Conclusion ΔVTI and ΔSV monitored by TTE before and after PLR could be employed for predicting fluid responsiveness of critical patients under the status of spontaneous respiration.Their value for prediction of critical patients could be further improved by combined employment of these two indexes of variation. Key words: Transthoracic echocardiography; Fluid responsiveness; Passive leg raising