Effect Of Inferior Vena Cava Ultrasound-guided Rehydration On Hemodynamics During Induction Of General Anesthesia In Patients Undergoing Gynecologic Surgery

Background and objective:Hemodynamic fluctuations in patients during the induction period of general anesthesia are more pronounced compared to the entire perioperative period,which are often related to the patients’ own cardiovascular status,the myocardial depressant effect of anesthetic drugs,and blood volume deficiency caused by the patients ’ preoperative water fast.Unstable hemodynamics may cause disturbance of the internal environment and inadequate perfusion of tissues and organs,etc.In order to fully expose the surgical field and reduce the occurrence of perioperative vomiting and aspiration in gynecological surgery,adequate gastrointestinal preparation is also needed,which may further cause insufficient blood volume of patients and increase the incidence of hypotension during the induction period.Therefore,reasonable rehydration during the induction period is more important.There are various clinical modalities to guide rehydration,such as Flo Trac /Vigileo system,CVP,PICCO system,SVV,PPV,etc.However,due to the high cost and invasive nature of the above modalities,they are not applicable in some routine gynecological procedures.Available clinical studies have shown that inferior vena cava ultrasound and inferior vena cava collapse rate can reflect patient volume responsiveness and guide preoperative rehydration,and for IVCCI≥43%,active rehydration is possible;when IVCCI < 43%,cautious rehydration is required.In this paper,we will investigate the effect of inferior vena cava ultrasound-directed fluid augmentation on hemodynamics during induction of general anesthesia in patients undergoing preoperative gynecologic surgery using a threshold value of 43%.Objects and methods:A total of 60 patients who were to undergo gynaecological surgery at the hospital between September 2022 and January 2023 were randomly selected.All patients were aged >20 years;18 kg/m2≤ BMI ≤ 30kg/m2;ASA class I-II;no chronic obstructive pulmonary disease,and were randomly divided into a control group(Group C)and an ultrasound group(Group U)with the aid of a random number table,with each group having30 patients in each group.All patients were given 2mg midazolam upon admission to the room in a flat position.inferior vena cava ultrasound was performed in both groups and the rate of inferior vena cava collapse was calculated.group C was given a restrictive rehydration strategy before induction with a rehydration rate of 4m L/kg/h.group U had an IVCCIguided infusion protocol: if the IVCCI was assessed to be ≥43%,a fluid shock of 5ml/kg was given within 30 min before induction of anaesthesia,and then assessed IVCCI and determine whether to continue giving 1/2 the previous fluid dose until the volume responsiveness threshold range of <43% was maintained.Both groups were treated with rehydration fluids and induction of anaesthesia was started 10 minutes later.Sufentanil 0.5ug/kg,Cisatracurium besilate 0.2mg/kg and Etomidate 0.3mg/kg were administered successively during induction.Mechanical ventilation capacity control mode is adopted,the tidal volume is 8ml/kg,the respiratory rate is 12 times/min,and end-tidal carbon dioxide partial pressure(PET-CO2)is maintained at 35-45 mm Hg.After 10 min of induction,the anesthesiologist in charge decided on the maintenance plan.The patients’ general information(age,ASA classification,BMI,procedure,history of hypertension,history of diabetes)were recorded,hypotension during the induction period,the number of ephedrine doses and the rate of use;Systolic blood pressure(SBP),diastolic blood pressure(DBP),mean arterial pressure(MAP)and heart rate(HR)were recorded 5min after receiving midazolam(T0)in calm lying position,1min(T1),3min(T2),5min(T3),7min(T4)and 9min(T5)after anesthesia induction.the incidence of postoperative adverse effects was recorded in both groups.Results:1.The differences in age,height,weight,BMI,ASA classification,history of hypertension and number of patients with IVCCI greater than the threshold between the two groups were not statistically significant.(P>0.05)2.Incidence of hypotension after induction of general anesthesia in both groups: 12 cases(40%)in group C were higher than 5 cases(16.7%)in group U.(P<0.05)3.The rate of ephedrine use in both groups was higher in 11 cases(36.3%)in Group C than in 4 cases(13.7%)in Group U.(P<0.05)4.The differences in the changes of SBP,DBP and MAP between the two groups of patients at different times were statistically significant(P<0.001),and the effect of the interaction of group and time on SBP,DBP and MAP was not statistically significant(P>0.05).There was no significant difference in SBP,DBP and MAP between the two groups(>0.05)Compared to T0,data from each group showed a decrease in SBP,DBP and MAP at T1,T2,T3,T4 and T5(P<0.001).Compared to T1,there was a statistically significant difference in the change in SBP,DBP and MAP at T2,T3,T4 and T5 for each group of data(P<0.001).There was a statistically significant difference in DBP and MAP at T3 between the two data groups compared to T2.Independent sample t-tests were performed for groups C and U at different times,and the differences in DBP and MAP at T3 were statistically significant.(P<0.05)5.Patients in both groups did not develop pulmonary oedema,and there was no statistical difference in the probability of postoperative nausea and vomiting.(P>0.05)Conclusion:The inferior vena cava collapse index of 43% can guide pre-induction rehydration in gynaecological surgery patients who have lost body fluids preoperatively,which is conducive to maintaining the haemodynamic stability of patients during the induction period and reducing the incidence of hypotension and the use of ephedrine during the induction period,and is worthy of further clinical application and study.