急性高容量血液稀释对患者靶控输注异丙酚意识消失时EC50的影响

目的 探讨急性高容量血液稀释(AHHD)对患者靶控输注(TCI)异丙酚意识消失时EC50的影响.方法 择期行脊柱手术或全髋置换术患者60例,年龄18～64岁,ASA Ⅰ或Ⅱ级,随机分为4组(n=15):异丙酚血浆靶浓度输注组(Tp组)、异丙酚效应室靶浓度输注组(Te组)、AHHD+Tp组和AHHD+Te组.入室后经30 min外周静脉输注乳酸钠林格氏液0.7 nl·kg-1·h-1,AHHD+Tp组和AHHD+Te组同时经颈内静脉输注4%琥珀酰明胶15 ml/kg行AHHD.AHHD结束后TCI异丙酚,初始靶浓度为1.2μg/ml,到达该浓度30 S后,采用警觉/镇静评分(OAA/S)评价患者的意识状态,然后以0.3 μg/ml的浓度梯度增加靶浓度,直至患者意识消失(OAA/S=0分),记录此时异丙酚的血浆靶浓度和效应室靶浓度.采用概率单位法计算异丙酚意识消失时的EC50及其95%可信区间(CI).结果 Tp组、Te组、AHHD+Tp组和AHHD+Te组意识消失时异丙酚的EC50及其95%CI分别为3.74(3.46～4.16)、2.32(2.17～2.42)、4.12(3.81～4.32)、2.38(2.14～2.56)μg/ml.与Tp组比较,AHHD+Tp组意识消失时异丙酚的EC50升高(P<0.05);与Te组相比,AHHD+Te组意识消失时异丙酚的EC50差异无统计学意义(P>0.05).结论 AHHD可升高患者TCI异丙酚意识消失时血浆靶浓度的EC50,对效应室靶浓度的EC50无影响.

Effect of acute hypervolemic hemodilution on EC50 of propofol by TCI for loss of consciousness

Objective To investigate the effect of acute hypervolemic hemodilufion (AHHD) on EC50 of propofol by target-controlled infusion (TCI) for loss of consciousness (LOC). Methods Sixty ASA Ⅰ or Ⅱ patients aged 18-64 yr scheduled for vertebral eolunm or total hip replacement surgery were randomly divided into 4 groups (n = 15 each) : group Ⅰ target plasma concentration of propofol (Tp) ;group Ⅱ target effect-site concentration of propofol (Te) ;group Ⅲ AHHD + Tp and group Ⅳ AHHD + Te. All the patients recoived iv infusion of lactated Ringer's solution 0.7 ml·kg-1 ·h-1 via peripheral vein for 30 min. At the same time 4% gelofusion 15 ml/kg was infused over 30 min via internal jugular vein in group Ⅲ and Ⅳ. At the end of gelofusine infusion TCI of propofol was started. The initial target concentration was set at 1.2 μg/ml. After the target concentration was steadily maintained for 30 s, the consciousness of the patients was evaluated by an anesthesiologist not involved in the study using OAA/S scale. The target concentration was increased in 0.3 μg/ml increment until the patients lost consciousness (OAA/S = 0). The target plasma concentration and effect-site concentration were then recorded. EC50 and 95% confidence interval (CI) of propofol for LOC were calculated by probit analysis. Results The ECho (95 % CI) of propofol for patients in group Tp, Te, AHHD + Tp and AHHD + Te (group Ⅰ-Ⅳ) were 3.74 (3.46-4.16), 2.32 (2.17-2.42), 4.12 (3.81-4.32) and 2.38 (2.14-2.56) μg/ml respectively. EC50 was significantly higher for loss of consciousness in AHHD + Tp group (group Ⅲ)than in Tpgroup (group Ⅰ), but there was no significant difference in EC50 between group Te and group AHHD + Te. Conclusion AHHD can increase the EC50 of target plasma concentration of propofol by TCI for LOC but has no effect on EC50 of target effect-site concentration.