Effectiveness Of Predicting Fluid Responsiveness By Mini-fluid Challenge Test In Patients In Prone Position

Background:After rapid infusion of liquid(about 250-300 ml of liquid)in a short period of time,if the stroke volume(or its replacement index)of the patient increases significantly(increasing by more than 10%),it indicates that the patient has volume responsiveness to liquid therapy and can be treated by volume therapy,so that the patient can get effective volume supplement.Traditionally,volume expansion is performed by'rapid infusion of 250 ml or more liquids to predict volume response,but repeated infusion in a short time may result in volume overload.However,the risk of volume loading test can be reduced due to the Mini-fluid Challenge test.Currently,there are few studies on volume response of patients in prone position,such as thoracolumbar posterior surgery,long operation time,large wound and more bleeding.Volume responsiveness of patients should be predicted in order to accurately judge the volume status of patients.In this study,the volume of fluid infusion during volume expansion was calculated according to body weight.To assess whether the degree of change in stroke volume caused by rapid infusion of small amounts of colloids(2ml/kg)can predict the effect of multiple doses of colloids(5ml/kg)by Mini-fluid Challenge test.Flotrac/Vigileo system was used to monitor each volume and related hemodynamic parameters.Comparing the stroke volume collected after two volume expansion,grouping analysis was conducted according to whether the stroke volume increased by more than 10%.Then to explore the validity of prone micro-liquid impact test in predicting volume response.Materials and methodsThe parameters of MAP,HR,SV,SVV,PPV,CI,CO and PI were monitored and collected for patients undergoing selective thoracolumbar posterior surgery.Before induction of anesthesia,crystal solution was the main infusion.Volume expansion was carried out in 6%Hes(130/0.4).The collection time points were TO before anesthesia induction(before oxygen inhalation);T1(before prone position);T2(after prone position),which was the baseline(immediately after volume expansion);T3 was recorded after 1 minute of infusion of 2 ml/kg colloid at a rate of 0.5 ml/kg/min.T4 was recorded after 1 minute of infusion of 3ml/kg colloid at the same rate,totaling 5 inl/kg colloid.(Note:All time points were collected before the operation started).At the end of the experiment,the changes of stroke volume at T3 and T4 time points were calculated compared with that at T2.The patients were divided into volume response group and non-volume response group.Statistical analysis used SPSS20.0 software to analyze the data.The general data of patients were expressed by median(quartile spacing),the measurement data of normal distribution were expressed by mean ± SD(x±s),and the analysis of variance of repeated measurements was used for comparison among groups at multiple time points.Receiver operating characteristics curves were used to evaluate the ability of Mini-fluid Challenge test to predict volume response,P<0.05 was statistically significant.ResultsPart 1:General situationThis study included 50 eligible patients.In the study,6 patients were treated with vasoactive drugs,and 3 patients with SV had inconsistent results with 10%after two volumetric expansions(from T2 to T3,from T2 to T4).All of them were excluded.There were 18 patients with volume responsiveness and 23 patients without volume responsiveness.There was no statistical difference in general data between the two groups.Part 2:Hemodynamic indicesIn volume response group,there were significant differences in stroke volume and variation of stroke volume at T3 and T4 time points compared with baseline.Compared with the non-volume response group,the changes of stroke volume variation at T3 and T4 time points were significant different.In the non-volumetric response group,compared with T2,there was no significant difference in stroke volume at T3 and T4,and there was no significant difference in stroke volume change at T3 and T4.Receiver operating characteristics curves of the subjects showed that the Mini-fluid Challenge test had a high ability to predict volume responsiveness.Other related hemodynamic indicators also showed differences before and after volume expansion.HR,PPV and SV in volume response group had statistical differences.Only HR in NRs group had statistical difference.HR,MAP,CO and CI decreased significantly before and after prone position.ConclusionsIn prone position surgery,volume responsiveness can be predicted by using Mini-fluid Challenge test,which is correlated with volume responsiveness predicted by using more fluids.Relevant hemodynamics changes before and after prone position.