Evaluation Of Stroke Volume Variation In Monitoring Volume State In Gastrointestinal Patients During Induction

Partâ… Evaluation of Stroke volume variation in monitoring volume state in gastrointestinal patients during inductionObjective To evaluate the accuracy and reliability of stroke volume variation(SVV) derived from FloTrac/Vigileo system in predicting fluid responsiveness in patients ventilated with different tidal volumes during gastrointestinal surgery.Methods Fifty ASAⅠ～Ⅱpatients without cardiac and pulmonary disease of both sexes aged 30-64 years undergoing elective gastrointestinal surgery were randomly divided into two groups:Conventional tidal volume group(group C,n₁=20) and low tidal volume group(group L,n₂=30).In addition to standard hemodynamic monitoring(HR,MAP,CVP),SVV,cardiac output(CO),cardiac index(CI),stroke volume(SV),stroke volume index(SVI),systemic vascular resistance(SVR),systemic vascular resistance index(SVRI) was monitored by FloTrac/Vigileo system.All patients were mechanically ventilated in intermittent positive-pressure ventilation(IPPV) mode[group C:tidal volume(V_T)= 8ml/kg,frequency(F)=12/min,positive end expiratory pressure(PEEP)=0,fractional inspired oxygen(FiO₂)=0.8,oxygen flow=2.0L/min;group L:V_T=6ml/kg,F=16/min, PEEP=0,FiO₂=0.8,oxygen flow=2.0L/min].After induction and tracheal intubation, 6%hydroxyethyl starch 130/0.4 solution(7mL/kg,rate 0.3mL·kg^-1·min^-1) was intravenous transfused.In two groups,all variables were assessed before and after fluid infusion.Results After volume replacement,In two groups,MAP,CVP,SVI and CI were increased,SVV and SVR were decreased significantly,while HR wasn't changed. Changes in SVV(group C,r=0.843,P=0.000;group L,r=0.742,P=0.000) and CVP(group C,r=0.608,P=0.001;group L,r=0.578,P=0.004) were significantly correlated to Changes in SVI,while changes in HR,MAP,SVR were not correlated to changes in SVI.SVV before fluid infusion(group C,r=0.909,P=0.000;group L,r= 0.758,P=0.000) were significantly correlated to changes in SVI,but no correlation was found between HR,MAP,CVP,SVR before fluid infusion and changes in SVI.By using receiver operating characteristic analysis,The best area under the ROC curve(AUC) was found for SVV(group C,0.852;group L,0.814),more than those of HR,MAP,CVP,SVR statistically.In group C,SVV value of 9.5%or more will predict an increase in the SVI of at least 25%in response to volume replacement with a sensitivity of 100%and a specificity of 57.1%;In group L,it was with a sensitivity of 91.3%and a specificity of 71.4%.Conclusion SVV derived from FloTrac/Vigileo system can predict fluid responsiveness in patients not only ventilated with conventional tidal volumes but also ventilated with low tidal volumes during gastrointestinal surgery. Partâ…¡The effect of rapid plasma volume expansion in patients undergoing gastrointestinal surgery during induction of general anesthesia on hemodynamics and oxygen balanceObjective To investigate the effect of different doses of rapid plasma volume expansion with 6%hydroxyethyl starch 130/0.4 solution in patients undergoing gastrointestinal surgery during induction of general anesthesia on hemodynamics and oxygen balance.Methods Sixty ASAⅠ～Ⅱpatients of both sexes aged 30-64years undergoing elective gastrointestinal surgery were randomly divided into three groups:6%hydroxyethyl starch 130/0.4 solution(Voluven,rate 0.3mL·kg^-1·min^-1) was intravenous transfused in 30min before induction,group A:5ml/kg;group B:7ml/kg;group C:9ml/kg.Left radial artery and right subclavian vein were cannulated under local infiltration for BP and CVP monitoring.ECG,SpO₂,P_ETCO₂ and HR were continuously monitored during anesthesia. Cardiac index(CI),systemic vascular resistance index(SVRI) and stroke volume variation(SVV) was continuously monitored by FloTrac/Vigileo system.30min before anesthesia,atropine 0.5mg and phenobarbital sodium 0.1g were intra-muscular injected. Anesthesia was induced with midazolam 2mg,etomidate 0.2mg/kg,fentanyl 3μg/kg and atracurium 0.6～0.8mg/kg.All patients were mechanically ventilated in intermittent positive-pressure ventilation mode[tidal volume=8ml/kg,frequency=12/min,positive end expiratory pressure=0,fractional inspired oxygen=0.8,oxygen flow=2.0L/min]. P_ETCO₂ was maintained at 35～45 mmHg and SpO₂ was maintained at 98%～100%. Anesthesia was maintained with sevoflurane,propofol,remifentanyl and intermittent i.v. doses of atracurium.Hemodynamic variables were recorded Immediately before fluid transfusion(T₀),after fluid transfusion just before induction(T₁),immediately after induction just before intubation(T₂),immediately after intubation(T₃),5min,10min,20min,60min after intubation(T₄～T₇).Arterial and venous blood samples were taken for blood gas analysis and determination lactic acid,blood glucose,Hb and Hct before volume expansion(t₀),the moment after volume expansion(t₁)and 1h after volume expansion(t₂).oxygen delivery(DO₂),oxygen extraction ratio(ERO₂),volume expansion rate and arterio-venous extraction of lactate(Lv-a) were calculated.Result(1) MAP and CI decreased in group A in T₂～T₇ and were unchangeable in group B and C.HR decreased in T₂ and T₄～T₇ and increased in T₃ in group A,while no change in group B and C.(2) CVP increased in three groups after fluid infusion and there were no difference among three groups.(3) SVRI decreased more seriously in group B and C than in group A after induction and lower in group C than in group B in T₂～T₄ and T₆～T₇.(4) SVV was lower in group B and C than in group A after intubation,and lower in group C than in group B in T₃～T₆.(5) Hb and Hct decreased after fluid infusion,the degree of decrease was in the order of C＞B＞A.(6) Volume expansion rate was in the order of C＞B＞A.(7) There were no differences in ScvO₂,Lv-a,ERO₂,pH,BE,PaO₂,PaCO₂,HCO₃^- and blood glucose among three groups.(8) ScvO₂,PaO₂ and DO₂ all increased in three groups after fluid infusion and the degree of increase of DO₂ was in the order of C＞B＞A.(9) ERO₂ decreased after fluid infusion in three groups.Conclusion Rapid plasma volume expansion with Voluven 7～9ml/kg can prevent hemodynamic fluctuation during induction,maintain the balance between oxygen supply and oxygen consumption during surgery,besides group with Voluven 9ml/kg can improve oxygen delivery.