| Background:In an aging society,the number of elderly people increases.With the increase of age,the prevalence of many diseases increases,and the number of elderly patients receiving surgical anesthesia increases.The tolerance of elderly surgical patients to narcotic drugs is reduced,and a long period of fasting and drinking before general anesthesia is likely to lead to insufficient blood volume,and large hemodynamic fluctuations are likely to occur after induction of general anesthesia.Perioperative hypotension usually occurs after anesthesia induction and before operation,which is called post-induction hypotension.Hypovolemia is a common factor inducing induced hypotension.The premise of improving the volume state is to accurately evaluate the volume state.Ultrasound examination of the inferior vena cava has a good correlation with volume status.The collapse index of inferior vena cava(IVC-CI),as a non-invasive and simple volume assessment technique,can be used to predict hypotension after general anesthesia induction.This study was to investigate the effect of fluid infusion guided by inferior vena cava collapse index before induction of general anesthesia on induced hypotension in elderly patients.Methods:50 elderly patients undergoing elective surgery were included.The condition of the inferior vena cava was evaluated by ultrasound in the preoperative preparation room 30 minutes before surgery,the diameter of the inferior vena cava was measured,the maximum value of inferior vena cava(IVCmax)and the minimum value of inferior vena cava(IVCmin)were measured,and the collapse index of the inferior vena cava(IVC-CI=(IVCmax-IVCmin)/IVCmax was calculated ×100%。The elderly patients with the collapse index of the inferior vena cava≥43%were randomly divided into the rapid rehydration group and the control group.The rapid rehydration group was given 12 ml/kg lactate Ringer’s solution for rapid volume expansion 30 minutes before induction,and the IVC-CI was evaluated every 10 minutes,until the IVC-CI was less than 43%.The control group did not receive infusion after the first IVC ultrasound evaluation.The two groups of patients entered the operating room to begin anesthesia induction,and recorded the heart rate,mean arterial blood pressure and peripheral blood oxygen saturation per minute after induction(subject to the end of induction drug administration)to 15 minutes after induction.The baseline data of patients were analyzed and the incidence of induced hypotension and the use rate of vasoactive drugs were compared between the two groups.The difference of mean arterial blood pressure and heart rate between the two groups after induction was compared by repeated measurement analysis of variance and independent sample t-test.Spearman correlation was used to analyze the correlation between the maximum diameter of the inferior vena cava,the minimum diameter of the inferior vena cava,the collapse index of the inferior vena cava and the volume of rehydration before and after fluid infusion.Results:There was no significant difference between the patients in the rapid rehydration group and the control group in gender,age,height,weight,hemoglobin,ASA grade,cardiac function grade,basic mean arterial pressure,basic heart rate difference,basic inferior vena cava maximum diameter,basic inferior vena cava minimum diameter,and basic inferior vena cava collapse index.The maximum diameter of the inferior vena cava(1.54±0.134 vs 1.72±0.11,),the minimum diameter of the inferior vena cava(0.80 ± 0.09 vs 1.03 ± 0.08),and the collapse index of the inferior vena cava(47.98±3.30 vs 39.92±2.40)in the rapid rehydration group were significantly different before and after rehydration.Compared with the control group(72%),the incidence of hypotension in the rapid rehydration group(32%)was lower,and the difference was statistically significant.The use rate of vasoactive drugs in the rapid rehydration group(20%)was significantly lower than that in the control group(52%).After induction of general anesthesia,the difference of heart rate between the two groups was not statistically significant,but the difference of mean arterial blood pressure between the two groups was statistically significant.The collapse index IVC-CI of inferior vena cava before and after fluid replacement,and the maximum diameter change of inferior vena cava before and after fluid replacement ΔIVCmax,minimum diameter change of inferior vena cava before and after fluid replacement ΔIVCmin,changes of inferior vena cava collapse index before and after fluid replacement ΔIVC-CI is correlated with fluid replacement.Conclusion:Before general anesthesia,targeted fluid infusion with the collapse index of inferior vena cava<43%can reduce the incidence of hypotension in elderly patients after anesthesia induction and reduce the use of vasoactive drugs. |
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