Clinical Study Of Common Carotid Artery Corrected Flow Time In Predicting Volume Response In Patients Undergoing Surgery And The Effect Of Positive Pressure Ventilation

Objective: In this study,we will study whether the corrected blood flow time of the common carotid artery can predict the volume reactivity of patients and whether the positive end-breath pressure ventilation will affect its sensitivity,specificity and threshold.Methods:Phase 1: A total of 80 patients with general surgery from December 2019 to November 2020 were included.After induction of general anesthesia,after hemodynamics was stable,the above indicators were measured in turn,and 7 ml/Kg of6% hydroxyethyl starch sodium chloride solution was quickly infused from the peripheral vein at 15-20 min,until the infusion is completed,and then the volume response is observed.Grouping according to ΔCO: Calculate ΔCO,that is,the percentage of CO change.ΔCO =(CO after capacity load-CO before capacity load)/CO×100% before capacity load.The ΔCO>15% group is regarded as the capacity expansion Response Group(R group),and the ΔCO<15% group is regarded as the capacity expansion non-response group(NR group),and the data are statistically analyzed.Phase2: a total of 29 patients with general surgery from December 2019 to November 2020 were included,3min after anesthesia induction,and after hemodynamics was stable,the patients were treated with PEEP =0,5,10 cm H20,respectively,after each maintenance for three minutes,after hemodynamics was stable,the corrected blood flow time of the patient was measured and recorded in turn,and then the volume expansion experiment was carried out by infusion of 6% hydroxyethyl starch at 7 ml/Kg.PEEP =0,5 and10 cm H20 were added immediately after the volume load experiment was completed,and the corresponding above indexes were recorded after the hemodynamics were stable for 3 minutes respectively.Grouping according to FTc: The threshold of FTc< Phase I trial is regarded as the capacity expansion Response Group(R group),and the other group is regarded as the capacity expansion non-response group(NR group),and the statistical analysis data.Results: in the first stage,CO and FTc of the two groups of patients before and after fluid infusion were statistically significant(P<0.05),MAP of group R was statistically significant before and after fluid infusion(P<0.05),HR was not statistically significant before and after fluid infusion.HR and MAP in NR group were not statistically significant before and after fluid infusion.The area under the ROC curve(AUC) predicted by FTc before volume load test was 0.7860.056(95% confidence interval(CI)was 0.676-0.896,P =0.000).The second stage: PEEP has no statistical significance on FTc,F(2,56)=1.930,P =0.155,capacity load factor has statistical significance on FTc,F(1,28)=9.381,P<0.05.The difference between FTc before rehydration test and FTc after rehydration test was statistically significant(P<0.05),and the difference was35.04ms(95%CI:11.607-58.480).When PEEP =0,5 and 10 cm H20,the area under ROC curve under FTc judgment capacity reactivity is 0.921,0.805,0.719(P<0.05),and FTc diagnostic thresholds are 323.42 ms,326.69 ms and 312.0ms respectively.Conclusion:Common carotid artery corrected blood flow time(FTc)can accurately predict the volume reactivity of patients during perioperative period,and is not affected by positive end-expiratory pressure ventilation,which can provide theoretical basis for fluid therapy of patients during perioperative period.