The Effects Of Combining Dexmedetomidine With Intravenous Anesthetics On Hemodynamic Variation During Tourniquet Inflation

Objective: We investigated the effects of combining dexmedetomidine withintravenous anesthetics on hemodynamic variations during tourniquet inflation undergeneral anesthesia and adverse effects after surgery.Methods:40patients undergoing orthopaedic surgery of the lower extremities ontourniquet inflation who were randomly assigned into two group: experimentalgroup(A group) and control group(B group),20patients respectively.Establish venouscirculation.ECG，HR，non-invasive blood pressure，SPO2and BIS were monitoredduring anesthesia.Mensuration circumference of the lower extremities of patients,non-invasive blood pressure were measured before induction of anaesthesia as baselinepressure. In both groups inserting a laryngeal mask after induction and mechanicalventilation.Both groups anaesthesia were maintained with propofol and remifentanilafter inserted laryngeal masks.In the group B,dexmedetomidine was loaded with0.5μg/kg over10min and was infused0.5μg/kg over1h.During surgery,we adjusted thedose of propofol according to the BIS and maintained it between45and55, the dose ofremifentanil was limted0.3μg/(kg.min).Before operation, applying a tourniquet toupper and middle third of thigh and wrapping before skin incision, then tourniquetinflation was inflated with45KPa. Measuring non-invasive blood pressure per5min,patients who developed tourniquet-induced hypertension, defined as more than a30%increase to baseline pressure in systolic or diastolic of blood pressure duringsurgery,were recorded,the occurrence time of tourniquet-induced hypertension wasrecorded too. If systolic blood pressure increased to more than170mmHg, vasoactiveagents were given and these patients were excluded from further analysis, the time ofoperation was greater than90min were excluded from further analysis.After surgery, thevenous anaesthetics were terminated and deflated tourniquet. The5mg dezocine was infused if patients,visual analogue scales(VAS) were more than7when the BIS ofpatients were more than85and the0.3mg ramosetron was infused to patients who hadnausea and vomitting after extracted laryngeal mask.The number of patients of bothgroups who developed tourniquet-induced hypertension and the time of origin oftourniquet-induced hypertension,the number of patients who developed shivering andnausea and vomiting after surgery were recorded.The systolic blood pressure, diastolicblood pressure, mean arterial blood pressure and heart rate were measured at thefollowing time points:after insert laryngeal mask(T0), immediately before tourniquetinflation (T1),30min after tourniquet inflation(T2),45min after tourniquetinflation(T3),60min after tourniquet inflation(T4),70min after tourniquet inflation(T5),immediately before tourniquet deflation(T6),5min after tourniquet deflation(T7),thedosage of intravenous anesthetics during surgery was recorded.All datas were statisticalanalyzed after surgery.Results:There were no significant differences infundamental state of the patientsbetween group A and group B. One patient in the group A and two patients in the groupB were excluded from the study because the time of tourniquet deflation was more than90min,two patient were excluded from the study because systolic blood pressureincreased to more than170mmHg.Ten patients and six patients developedtourniquet-induced hypertension to group A and group B respectively,the incidence ratewas58.8%and33.3%respectively,it had significantly statistic difference betweentwo group(sP<0.05).The time of inflation that patients developed to tourniquet-inducedhypertension was(47.0±5.3min)and (59.2±3.7min)respectively of group A and groupB, it had significantly statistic difference between two groups(P<0.01). The systolicblood pressure, diastolic blood pressure and mean arterial blood pressure were lower ingroup A than group B at T1, they had significantly statistic differences(P<0.01). Thesystolic blood pressure, diastolic blood pressure and mean arterial blood pressure werehigher in group A than group B at T5and T6, they had significantly statistic differences(P<0.05)；The percentage increase of the systolic blood pressure and mean arterialblood pressure to baseline haemodynamic data were higher in group A than group B atT5and T6, they had significantly statistic differences(P<0.05).The heart rates wereincreased to both groups during tourniquet inflation, the heart rates were higher in groupA than group B at T5and T7,it had significantly statistic differences(P<0.05), theheart rates increased at T7to both groups,they had significantly statistic differences inintragroup(P<0.05). The dosage of propofol during surgery of group A was larger than group B,65.9±9.3mg/(kg.min) vs.48.5±7.2mg/(kg.min),it had significantly statisticdifference(P<0.01).Thirteen and two patients,visual analogue scales(VAS) were morethan7of group A and group B respectively, they had significantly statistic differences(P<0.05).Seven and two patients who developed to shivering of group A and Brespectively,they had significantly differences(P<0.05).Conclusion:Dexmedetomidine combine propofol and remifentanil can attenuateblood pressure and decrease incidence rate of tourniquet-induced hypertension in acertain extent, stabilize hemodynamics during tourniquet inflation under generalanaesthesia and decrease adverse effects after surgery.