Effects Of Acute Normovolemic Hemodilution On Plasma Concentration,anesthesia Depth And Adrenocortical Function After Target Controlled Infusion Of Etomidate

Objective:To observe the effect of Acute normovolemic hemodilution（ANH）used in orthopedic surgery on the Target Controlled Infusion（TCI）concentration of etomidate hemodilution,depth of anesthesia,and adrenal function.To provide theoretical basis for rational drug use and correct application of ANH.Methods:Sixty patients who underwent orthopedic surgery in Gongli Hospital Affiliated to Naval Medical University from September 2021 to December 2022 were selected.The surgery lasted about 3 hours and was first performed in the morning to avoid the influence of the circadian rhythm of adrenocortical hormone on the results.The age range was 20 to 60 years,the ASA grade was I to II,the BMI19 to 28kg/m²,Hb≥120g/L,Hct≥35%.The patients were randomly divided into two groups:ANH group（group A）and control group（group B）,with 30 cases in each group.The two groups were given0.05mg·kg-1 midazolam,0.7ug·ml-1 etomidate plasma target concentration,0.5ug·kg-1sufentanil and 0.2mg·kg-1 cisatracurium for anesthesia induction.Remifentanil 0.1-0.2ug·kg^-1·min^-1 and etomidate plasma target concentration 0.4-0.8 ug·ml-1 were maintained during the operation to maintain BIS values in the range of 40-60.Group A started ANH after the patients’vital signs were stable,the target Hct was 28%-30%,all drugs were stopped at the end of the operation,and autologous blood transfusion was completed within 1 hour.Group B was treated with routine infusion.BIS values were observed and recorded in 2 groups before ANH（T₁）,after ANH（T₂）,immediately after surgery（T₃）,10min（T₄）,20min（T₅）,30min（T₆）,60min（T₇）and 120min(T₈),respectively.The concentrations of etomidate in plasma collected from the blood bag immediately(T_C1),stored in the blood bag for 1h(T_C2),and transfused immediately(T_C3)at T₃～T₈ time points and in group A were detected by liquid chromatoc-tandem mass spectrometry（LC-MS/MS）.The values of CO,SVV,MAP and HR were recorded before anesthesia induction（T₀）,T₁,T₂,T₃ and T₆ time points,and the recovery time of patients and the recovery score at T₆-T₈ time points were recorded.The serum or plasma concentrations of COR,ALD and ACTH were detected by chemiluminescence immunoassay before surgery（T₀）,after surgery（T₃）,24h after surgery（T₉）and 48h after surgery(T₁₀).Results:（1）There were no significant differences in the general situation,type of operation,operation duration and total dosage of etomidate between the two groups（P>0.05）;The total infusion volume in group A was higher than that in group B（P<0.05）.（2）Compared with group B,CO decreased and SVV increased in group A at T₂（P<0.05）.（3）The BIS value of group A at T₄ and T₅ was significantly lower than that of group B（P<0.05）;The recovery time of group A was significantly longer than that of group B（P<0.05）;The Aldret score of group A was lower than that of group B at T6 and T₇（P<0.05）.（4）Compared between the two groups,the blood concentration of etomidate in group A was significantly higher than that in group B at T₄（P<0.05）,there was no difference in plasma concentrations between the two groups at other time points（P>0.05）.The plasma concentration of etomidate in group A decreased with time,but there was no significant difference among the three time points（P>0.05）.（5）There were no significant differences in the concentrations of COR,ALD and ACTH between the two groups（P>0.05）.Compared with preoperative results,COR and ALD were decreased in both groups after surgery（P<0.05）and increased ACTH（P<0.05）,and the concentrations of COR,ALD and ACTH in both groups returned to the preoperative levels at 24 and 48hours after surgery.Conclusion:The plasma etomidate concentration of ANH diluted blood changed slightly during the isolation period in vitro,and only briefly affected the plasma etomidate concentration after transfusion,increasing the depth of anesthesia and prolonging the recovery time of patients to a certain extent.The intraoperative hemodynamics of ANH was stable in orthopedic surgery patients with TCI etomidate,and the total amount of etomidate did not change,which did not enhance the inhibitory effect of etomidate on adrenal cortex function.ANH can be safely used in orthopedic surgery patients with TCI etomidate.