不同麻醉下老年患者静脉输注乳酸钠林格氏液的容量动力学

目的 比较不同麻醉下老年患者静脉输注乳酸钠林格氏液容量动力学的差异.方法 择期行上腹部手术老年患者30例,年龄65～79岁,ASA Ⅰ或Ⅱ级,随机分为2组(n=15):单纯全麻组(GA组)和硬膜外复合全麻组(GE组).GE组经T8.9硬膜外穿刺置管,注入2%利多卡因4 ml使阻滞平面达T4,然后硬膜外给予0.25%布比卡因8～10 ml.2组静脉注射咪达唑仑2 mg、芬太尼3μg/kg、异丙酚1.5 mg,kg和琥珀胆碱1.5 mg/kg麻醉诱导,气管内插管后行机械通气.麻醉诱导后2组经30min静脉输注乳酸钠林格氏液30 ml/kg,随后以0.1 ml·kg-1·min-1的速率继续输注60 min.连续监测心率、平均动脉压、中心静脉压、心脏指数、每搏量指数、胸内血容量指数及血管外肺水容量指数;桡动脉采血测定血红蛋白浓度和红细胞压积;记录试验过程中的尿量;应用容量动力学理论和物质守恒定律,计算中央容量稀释率、血浆容量增加、容量扩张效率、外周容量增加和清除率(K).尿量与Kr进行直线相关分析.结果 GA组和GE组乳酸钠林格氏液分布均符合容量动力学二室模型.与GA组比较,GE组中央容量稀释率、血浆容量增加和容量扩张效率升高,尿量和Kr减少(P<0.05),外周容量增加差异无统计学意义(P>0.05).GA组尿量与Kr呈正相关(r=0.551,P<0.05);GE组尿量与K呈正相关(r=0.531,P<0.05).结论 与单纯全麻比较,老年患者硬膜外复合全麻下静脉输注乳酸钠林格氏液的容量扩张效率增强.

Volume Kinetics of Ringer' s solution during different anesthesia in elderly patients

Objective To investigate the volume kinetics of intravenous Ringer's solution during different anesthesia in elderly patients. Methods Thirty ASA Ⅰor Ⅱpatients aged 65-79 yr undergoing elective upper abdominal surgery were randomly assigned into 2 groups (n = 15 each) : group Ⅰ general anesthesia (GA) and groupⅡ GA + epidural block (CE). In CE group epidural catheter was placed at T8-9 interspace. Correct placement was verified with 2% lidocalne 4 ml. Then 0.25% bupivacaine 8-10 ml was given via epidural catheter. General anesthesia was induced with midasolam 2 rag, fentanyl 3 μg/kg and propofol 1.5 mg/kg. Tracheal intubation was facilitated with sueeinyl choline 1.5 mg/kg. The patients were mechanically ventilated and PETCO2 was maintained at 40 nun Hg. Anesthesia was maintained with 0.5-0.6 MAC isoflurane inhalation and intermittent iv boluses of vecuronium. After induction of anesthesia Ringer's solution 30 ml/kg was infused over 30 min followed by continuous infusion at 0.1 ml·kg-1·min-1 during the next 60 min in both groups. Radial artery was cannulated for MAP monitoring and blood sampling. Right internal jugular vein was canunlated for CVP monitoring. A thermal dilution catheter was inserted into femoral artery and was connected to PiCCO monitor (Pulsion Co, Germany) together with CVP line. Hb concentration and Her were measured every 5 min during the Fast 60 min and then every 10 min in the next 30 min and plasma dilution and plasma volume expansion were calculated. MAP, HR, ECG, CVP, SpO2, cardiac index (CI), stroke volume index (SVI), intrathoracie blood volume index (rrBI) and extravascular lung water index (EVLWI) were continuously monitored during the experiment. Results The two groups were comparable with respect to age, M/F sex ratio, body weight and height and duration of operation. There were no significant differences in MAP, HR, CVP, CI, SVI, ITBI and EVLWI between the 2 groups. Volume kinetics analysis showed that the distribution of the infused Ringer's solution was accordant with a two-compartment model during anesthesia in both groups. The central compartment was smaller, peripheral compartment larger and elimination rate slower in GE group than in GA group. The plasma volume expansion and volume expansion efficiency were greater and urine output was less at the end of experiment in group GE than in group GA. K, correlated well with urine output. Vital signs were fairly stable during the whole period of infusion. In both groups there was no significant increase in extravascular lung water during and after Ringer's solution infusion. Conclusion The efficacy of Ringer's solution for volume expansion is better during epidural block combined with general anesthesia than during general anesthesia in elderly patients.