The Value Of Carotid Artery Corrected Flow Time In Evaluating Severe Patients' Blood Volume

Background:The evaluation of blood volume in severe patients has always been a focus by clinicians.Accurately and rapidly evaluation of blood volume can guide for clinical treatment.The clinicians can judge the blood volume according to patients' blood lactic acid,clinical symptoms and signs,urine volume,blood pressure and so on.But the accuracy of this method is poor,it is a kind of empirical diagnosis,and depends on the skill level of the clinician.At present,Central venous pressure(CVP),Global end-diastolic volume index(GEDVI),Intrathoracic blood volume index(ITBVI)Inferior vena cava collapsibility index(IVCCI)are the main indexes for evaluating blood volume in clinic,but the most of them above indexes are invasive.And the accuracy of CVP in evaluating blood volume has been questioned in recent years.Although the ITBVI and the GEDVI can assess the blood volume accurately,their equipment is expensive and is an invasive index.At the same time,the operator requirements are high,so the clinical promotion is limited.The IVCCI is noninvasive and convenient to operate,but its accuracy is questioned for patients who use ventilator,and it is difficult to obtain images for patients with more abdominal air,obesity and abdominal surgery.In recent years,it has been suggested that carotid artery corrected flow time(FTc)can be used to evaluate blood volume,but most of the subjects studied by foreign scholars are blood donors,diarrhea and vomiting patients,and renal dialysis patients.The purpose of this study was to investigate the value of carotid artery corrected flow time in the evaluation of blood volume in severe patients.Objective:To investigate the value of carotid artery Corrected flow time in the evaluation of blood volume in severe patients.Methods:Selected the 32 hypovolemic patients who can obtained carotid artery spectrum in the Intensive care unit.The systolic flow time(ST),Cycle time(CT),Heart rate(HR),Resistance index(RI),Mean arterial pressure(MAP)were measured.After 24 hours fluid infusion,repeated again and recorded the volume of fluid.and try to collected the NT-ProBNP.And compared the severe patients' FTc to the healthy population in the physical examination department of our hospital.Shapiro-Wilk(W test)was used to detect the normality of the data.The Pearson was used to analyse the relationship of FTc and MAP,HR,RI.Independent t-test was used to analyse the severe patients' FTc and the physical examination person's FTc.Paired t-test was used to analyse the severe patients' FTc before and after fluid infusion.The correlation between?FTc and Ablood volume was analyzed,and the regression equation between ?FTc and Ablood volume was calculated.The FTc to predict blood volume were evaluated by receiver operating characteristic(ROC)curves.Results:1.The were 32 hypovolemic patients,23 males,36y-87y(mean age 61.74±13.50 years)and 9 females,48y-76y(mean age 61.22±10.59 years).The were 82 healthy people,30 males,21y-53y(mean age 36.43±8.04)and 52females,24y-57y(mean age 40.15±8.82).2.The hypovolemic patients' MAP before and after fluid infusion are:87.31±11.39mmHg,87.11±11.55mmHg;HR:83.88±15.42,86.75±19.02;RI:0.72±0.06,0.74±0.05;FTc:10.25±1.24ms0.5,FTc:10.42±1.01ms0.5,NT-ProB NP:958.656±1516.836ng/L,1123.156±1916.893ng/L.The healthy people:MAP:83.92±7.99mmHg,HR:70.89±8.88,RI:0.72±0.05,FTc:10.78±0.46 ms0.53.It was confirmed by Shapiro-Wilk(Wtest)that the FTc and HR?RI?MAP.?FTc were in accordance with the normal distribution.FTc had no correlation with HR,MAP(P>0.05),and had correlation with RI(P=0.027).The FTc of hypovolemic patients were shorter than the healthy population,there was a significant difference in FTc between patients with hypovolemic blood volume and the physical examination person' before fluid infusion(P=0.025).The FTc was no significant difference in severe patients before and after fluid infusion(P>0.05).?FTc was positively correlated with Afluid volume(r=0.45,P=0.01),the equation was?FTc=3.76×10-4×?blood volume+0.192.The ROC curve area of FTc predict low blood volume status was 0.638(95%,CI 0.494-0.782),P=0.022.Conclusion:The hypovolemic patients carotid artery corrected flow time was shorter than the healthy,it can assess to the severe patients' blood volume,but it can be affected cardiac function.The volume response and threshold of carotid artery FTc in assessing blood volume need further study.