ABSTRACT
Objective:To evaluate the effect of dexmedetomidine on the blood concentrations of ropivacaine during sciatic nerve block in rabbits.Methods:Twelve New Zealand rabbits of both sexes, weighing 2-3 kg, were randomly divided into ropivacaine group (R group) and ropivacaine mixed with dexmedetomidine group (RD group). The right femoral vein was cannulated for blood sampling in both groups, 0.375% ropivacaine 3 ml was injected around the left sciatic nerve in group R, and 0.375% ropivacaine 3 ml containing 1.5 μg/kg dexmedetomidine was injected instead in group RD.Blood samples from the right femoral vein were collected before nerve block (T 0) and at 15, 30, 45, 60, 120 and 180 min after nerve block (T 1-6) for determination of plasma concentrations of ropivacaine using high-performance liquid chromatography after centrifugation, and concentration-time curves were plotted. Results:Compared with group R, the blood concentrations of ropivacaine were significantly decreased at T 1-3 ( P<0.05), no significant change was found in the blood concentrations of ropivacaine at T 4-6 ( P>0.05), the peak blood concentration of ropivacaine was significantly decreased ( P<0.01), and no significant change was found in the time to peak blood concentrations of ropivacaine or area under the concentration-time curves in group RD ( P>0.05). Conclusions:Dexmedetomidine can decrease the blood concentrations of ropivacaine during sciatic nerve block in rabbits.
ABSTRACT
Objective To explore the effect of different controlled hypotension method on the blood flow of the vertebral vein by measuring of blood flow of vertebral vein in rabbits. Methods Eighteen New Zealand rabbits,weighing 2-3 kg,were rando mly divided into three groups (n =6 each).Group S maintained MAP (90±5)mm Hg,group GTN reduced MAP to the base value of (70±10)% by using nitroglycerin 0.5 μg·kg-1 ·min-1 and esmolol 2.5 μg·kg-1 ·min-1 (ni-troglycerin∶esmolol= 1∶5 ),group SNP reduced MAP to the base value of (70 ± 10 )% by using sodium nitroprusside 0.5 μg·kg-1 ·min-1 and esmolol 2.5 μg·kg-1 ·min-1 (sodium nitroprusside∶es-molol=1∶5).The controlled hypotension model was established after intravenous general anesthesia. The blood flow of vertebral vein in rabbits were measured by ultrasonic measurement system (Terason 2 000 system ) before controlled hypotension and 1 hour after controlled hypotension. Results The MAP before controlled hypotension in group S (89.0 ± 5.2 )mm Hg,group GTN (91.5± 9.6 )mm Hg,group SNP (92.0 ± 5.7 )mm Hg had no significant difference.The blood pressure before and after the experiment had no significantly difference in group S.The blood pressure after controlled hypotension had no significant difference in group GTN and group SNP,but lower than that before controlled hypotension (P <0.05).Compared with group S,the blood flow of verte-bral vein in group GTN and group SNP were significantly reduced (P < 0.05 ).The blood flow in group GTN was significantly reduced compared with that in group SNP (P <0.05 ).Conclusion In the experiment,the combination of nitroglycerin and esmolol can better reduce blood flow of vertebral vein than that of nitroprusside and esmolol,that it is suitable for the control of hypotension in spinal surgery.
ABSTRACT
Objective To compare the effects of different levels of controlled low central venous pressure (CVP) on blood loss in patients undergoing hepatic lobectomy. Methods One hundred ASAⅠ -Ⅱ patients, aged 28-78 yr, weighing 39-90 kg, undergoing elective hepatic lobectomy under general anesthesia, were randomly divided into S groups ( n = 20 each) with CVP controlled at 1, 2, 3, 4 and 5 mm Hg during the course of operationrespectively (groups CVP1-5 ) . Anesthesia was induced with midazolam, fentanyl, etomidate and vecuronium. The patients were tracheal intubated and mechanically ventilated. Anesthesia was maintained with iv infusion of propofol and remifentanil, inhalation of isoflurane and intermittent iv boluses of vecuronium. CVP was maintained at the predetermined levels by restricted infusion or by administration of diuretics or vasoactive agents and so on during operation. The blood loss before, during and after removal of the diseased liver parenchyma ( V1-3 ) was recorded.The liver parenchyma transection area ( TA) was determined and the blood loss per transaction area ( VTA ) was calculated. Fluid infusion and blood transfusion were recorded during the three time periods mentioned above. MAP and HR were recorded before operation, at 5 min after removal of the diseased liver parenchyma was started and at the end of operation. Results Compared with group CVP5, the MAP during removal of the diseased liver parenchyma in groups CVP1,2 , V2 and VTA in groups CVP1-3,and the percentage of patients who needed blood transfusion during operation and the amount of fluid infused before completion of removal of the diseased liver parenchyma in groups CVP1-4 were significantly decreased ( P ＜ 0.05) . Compared with group CVP4 , V2 , VTA and MAP during removal of the diseased liver parenchyma were significantly decreased in group CVP2 and the amount of fluid infused was significantly increased before removal of the diseased liver parenchyma was completed in group CVP,( P ＜ 0.05) .Conclusion When CVP is controlled at 3 mm Hg, the hemodynamics is stable and blood loss is less during hepatic lobectomy.