| BackgroundFluid resuscitation is an important component in the management of septic shock.However,only 40-50%of patients with unstable haemodynamics can benefit from fluid therapy.On the other hand,fluid overload is associated with increased mortality in critically ill patients.Despite the fact that fluid challenge(FC)has been considered as gold standard for evaluating fluid responsiveness,there is a wide divergence in how to perform it.Among them,assessment time for FC raises lots of concerns.Most previous studies showed that the assessment time of response to a FC ranged from the end point of administration to 30 minutes(min)after completion of the FC.However,the haemodynamics of patients may change over time after FC,which may affect the assessment time of fluid responsiveness.On the other hand,the difference in intravascular distribution caused by different types of fluids(e.g.,crystalloid or colloid fluid)used may also affect the assessment time.In addition,though the change in ScvO2(?ScvO2)before and after FC in septic shock patients has shown predictive value in fluid responsiveness,the time effects and influencing factors are still unclear.ObjectiveFirst,to explore the optimal assessment time for fluid challenge(FC)with crystalloid or colloid in patients with septic shock;Second,to evaluate the time effect and the influencing factors of ?ScvO2 in predicting fluid responsiveness.MethodsA prospective study was conducted.A total of 40 septic shock patients monitored with pulmonary catheters were enrolled in the Medical ICU of the Peking Union Medical College Hospital from Nov 2016 to Jan 2019.All included patients received FC and were divided into two groups according to the types of fluid used,that is,crystalloid group(n=20)and colloid group(n=20).Haemodynamic variables included cardiac index(CI),heart rate(HR),mean artery pressure(MAP),central venous pressure(CVP),systemic vascular resistance index(SVRI)and pulmonary arterial wedge pressure(PAWP)were measured at baseline,immediately(0 min),and at 10,30,45,60,90 and 120 min after FC.Meanwhile,all the blood gas analyses from arteries,central veins and mixed veins were sampled and measured immediately at the above time points.Oxygen metabolism parameters included arterial oxygen saturation(SaO2),central venous oxygen saturation(ScvO2),oxygen delivery index(DO2I),oxygen consumption index(VO2I),lactate and hemoglobin(Hb)were recorded or calculated.Fluid responsiveness were defined as CI increased by more than 10%after FC.Accordingly,the patients in crystalloid or colloid groups were divided into subgroups of fluid responders and nonresponders,respectively.The difference between the crystalloid or colloid groups or differences among the subgroups were analyzed.Repeated measures of analysis of variance were used.The area under the curve(AUC)for the changes of ScvO2 and other physiological parameters(CVP,HR,SBP,DBP,SVRI and MAP)were analysed.Finally,the values of AScvO2 was adjusted by predefined formula.Results:All the 40 patients were included in the final analysis,with 20 patients in the crystalloid group and colloid group,respectively.Overall,no differences were observed with regard to baseline clinical characteristics and prognosis between the two groups.The main findings in current study included:?Of the included patients,26 were fluid responders,with 12 in colloid group and 14 in crystalloid group.As to the 14 nonresponders,8 were in colloid group and 6 in crystalloid group.Among the responders,19 were immediate responders,and 2 of colloid group became responders at 30 min after FC,while 4 and 1 of crystalloid became responders at 10 min and 30 min after FC.? The CI changes between crystalloid or colloid fluid groups after FC:CI increased significantly in both crystalloid and colloid group at the end of FC.In the colloid group,volume expansion increased the CI to maximum at 30 min after FC.At 60 min after FC,an increased in CI greater than 10%was also observed.In the crystalloid group,CI increased to maximum at 10 min and decreased to baseline at 45 min.An increased in CI greater than 10%was also observed at 10 min after FC.In addition,there was no significant difference in CI change between the groups at different time points during follow-up.?CI did not change over time in nonresponders subgroups,whereas in responders subgroups,CI increased parallelly to that in both crystalloid and colloid groups over time.Meanwhile,an increased in CI more than 10%was also observed during 0-30min after FC.There was significant difference in CI change between the responders from colloidal group and crystalloid group at 30,45,60,90 min after FC.?The diagnostic performance of ?MAP,?SBP,?DBP,AHR and ?CVP after FC were poor,while ?ScvO2 estimates adequately fluid-induced changes in CI,which allows the definition of fluid responsive to FC.However,the predictive accuracy decreased significantly over time after FC,expect in crystalloid group.? The relationship between AScvO2 and ACI during FC is dependent on changes in SaO2,VO2I and Hb.However,the predictive ability of AScvO2 to fluid responsiveness improved significantly after adjustment by VO2I but not Hb and SaO2.Conclusions1.Haemodynamic changes were significantly difference between crystalloid and colloid after FC in patients with septic shock.Therefore,the assessment timing of fluid responsiveness should be treated differently.The optimal assessment time of colloid group may be prolonged to 30 min after FC while that of crystal group can be at 10 min after FC.2.?ScvO2 can reliably predict the fluid responsiveness in patients with septic shock used of crystalloid or colloidal liquids,but the predictive accuracy decreased over time after FC.In addition,compared with SaO2,and Hb,VO2I changes after FC significantly affected the relationship between ?ScvO2 and ?CI during FC.Thus,the predictive ability of ?ScvO2to fluid responsiveness can be improved significantly after adjustment by VO2I. |
PDF Full Text Request