| Objective: This trial was designed to evaluate the influence of acute hypervolemic hemodilution (AHH) on the dose-response relationships of vecuronium, and to instruct the clinical application of the vecuronium during acute hypervolemic hemodilution.Methods: Forty male patients, ASA grade I - II , scheduled for elective esophageal carcinoma surgery were included in the study. Patients were excluded if they had cardiac, pulmonary, renal, hepatic, neurological, endocrine diseases. Those with a body weight more than 10% greater than the idea or with anemia (i.e, hemoglobin concentration 120g/l) were also excluded. Twenty patients, underwent acute hypervolemic hemodilution (group AHH, n=20), and twenty patients did not received hemodilution as controls(group C, n=20). All patients were premedicated with diazepam 0.2mg/kg, atropine 0.01mg/kg intramuscularly 0.5h before anesthesia. After topical anesthesia with 4% lidocaine, anesthesia was induced with IV thiopental 4-6mg/kg and fentanyl 2-4ug/kg. the trachea was intubated without the aid of a muscle relaxants, and general anestheia was maintained with 2% isoflurane (total flow of 0.51/min),and further increments of thiopental 50-100mg or fentayl 50-lOOug/kg as required to keep BIS index at about 45 ?5. Immediately after anesthesia was stable, 5%G.S 8-10ml/kg was infused to supplement the fluid deficiency owing to an overnight fast, then 6% hydroxyethyl starch 15ml/kg was infused intravenously at a rate of 50ml/min in AHH group, and blood loss was replaced by an equal volume of HES solution, Ringer's solution was infused in a volume equal to urine output plus the fluids loss from the wound; the patients in group C was infused as usual. SP, DP, MAP, SPO2, ECG, BIS were monitered during the whole procedures. Blood sample was taken at time T0 and T,. Hb, Hct, K+, Na+, Cl-, iCa2+, TPP, ALB were measured at different time. Neuromuscular function was assessed by TOP stimulation of HXD-1 with the percentage depression of T, responsed as the study parameter. The dose-response relationship of vecuronium were determined with the cumulative dose-response technique. A total dose of 40ug/kg of vecuronium was given in four dose (15,10,10,5ug/kg) and administered cumulatively. Each dose of vecuronium was injected as an IV bolus over <5s into a rapidly running IV infusion. Each dose increment was given only after the effect of the previous dose had reached a stable response , defined as three equal. If 90% or more of twitch depression was achieved after the second increment dose , the third increment dose was not used. All data were gotten before the operation. Theindividual dose-response relationship was examined by least squares linear regression of the logarithm of each dose against a probit transformation of the depression of T, response relative to Tc. The doses required for 50%, 90%, and 95% T\ depression (ED50, ED, and ED95 respectively) were calculated from the regression line. Then the mean dose-response relationships of two groups were compared.Results: (l)In the hemodilution patients, the level of Hct and concentrations of hemoglobin decreased from 41.16 +3.85% to 29.70+4.37%and from 135.91+11.04 g/L to 107.6 +10.81g/L respectively; while the total plasma protein and albumin decreased by 25.31% and 23.22%. Compared with preoperative values, Hb, Hct, TP, Alb, all blood electrolytes (except for Cl" and iCa2+) decreased significantly in patients who had hemodilution but remained stable in the control group. There were no significant difference regarding blood gas data within and between the two groups.(2) The tl, t2 and t3 increment were 7.67 + 1.53, 4.15 + 0.63, and 3.59+0.48min, respectively, in the hemodilution group; and 6.66 + 0.61, 3.71 + 0.53, and 2.98 +0.73min in the control group. They did not differ significantly between the two groups.(P>0.05)(3) Compared with those in the control patients, the ED50, ED90, and ED95 of vecuronium in the hemodilution patients were increased by 23.42%, 21.90% and 24.72%(P<0.05). The slope of the dose-response cur...
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