RESUMEN
Objective To investigate the effect of different dose of dexmedetomidine for pre-venting the visceral traction reaction during caesarean section under spinal anesthesia.Methods Two hundred ASA physical status Ⅰ-Ⅱ patients,full-term primiparas scheduled for elective cesarean sec-tion were enrolled in this randomized,placebo-controlled study.Patients were randomly allocated to receive dexmedetomidine in four groups:group C (0.9% normal saline),group D1(dexmedetomidine 0.6 μg/kg),group D2(dexmedetomidine 0.8 μg/kg),group D3 (dexmedetomidine 1.0 μg/kg),50 cases in each group.Two minutes after cutting umbilical,groups D1,D2,D3 received an intravenous infusion single-dose of 0.6,0.8,1.0 μg/kg dexmedetomidine respectively for 10 minutes.Group C was injected the same dose of saline.Maternal blood pressure (BP),heart rate (HR),Ramsay scores,visceral traction reaction conditions were recorded at three points:before iv (T0 ),10 min af-ter iv (T1 )and abdominal exploration (T2 ).Results As for the inhibition of visceral traction pain, groups D2 and D3 were obviously better than groups D1 and C,and there was no statistically signifi-cant difference between groups D2 and D3 at T2 (P <0.05 ).The effects of slowing down heart rate and increasing blood pressure were weaker in group D2 than that in group D3 at T2 .Ramsay scores were higher in groups D2 and D3 than in groups D1 and C (P <0.05),and there was no significant difference between groups D2 and D3 at T2 .Conclusion Administration of dexmedetomidine 0.8 μg/kg could alleviate the visceral traction reaction and had little effect on maternal hemodynamics.