摘要目的 评价右美托咪啶对体外循环(CPB)心内直视手术患者脑氧代谢和糖代谢的影响.方法 择期行CPB二尖瓣置换术患者58例,性别不限,ASA分级Ⅱ或Ⅲ级,年龄32～64岁,体重52～90 kg,采用随机数字表法,将其随机分为2组(n=29):对照组(C组)和右美托咪啶组(D组).气管插管后D组静脉输注右美托咪啶0.5μg·kg-1·h-1至术毕,C组给予等容量生理盐水.分别于CPB开始前鼻咽温度为36℃时、CPB期间鼻咽温度降至30℃时、心脏复跳时以及心脏复跳30 min时采集桡动脉和颈内静脉球部血样,进行血气分析,测定血糖和乳酸浓度,计算动脉血氧含量、脑动脉-静脉血氧含量差、脑氧摄取率、脑动脉-静脉血糖含量差和脑动脉-静脉乳酸含量差.结果 与C组比较,D组CPB期间鼻咽温度降至30℃时脑动脉-静脉血氧含量差和脑氧摄取率降低(P＜0.05),动脉血氧含量和糖代谢指标差异无统计学意义(P＞0.05).结论 术中静脉输注右美托咪啶0.5 μg·kg-1 ·h-1可降低CPB心内直视手术患者脑氧代谢率,有助于维持脑氧供需平衡,而对脑糖代谢无明显影响.

abstractsObjective To investigate the effects of dexmedetomidine on cerebral oxygen and glucose metabolism in patients undergoing mitral valve replacement under cardiopulmonary bypass (CPB).Methods Fiftyeight ASA Ⅱ or Ⅲ patients of both sexes aged 32-64 yr weighing 52-90 kg undergoing mitral valve replacement were randomly divided into 2 groups (n =29 each): control group (group C) and dexmedetomidine group (group D).Dexmedetomidine was infused iv at 0.5 μg· kg- 1 · h- 1 starting after tracheal intubation until the end of operation in group D,while in group C equal volume of normal saline was infused instead of dexmedetomidine.Blood samples were collected from radial artery and jugular venous bulb for blood gas analysis and determination of glucose and lactate concentrations before CPB (T1,nasopharyngeal temperature =36 ℃ ),during CPB (T2,nasopharyngeal temperature =30 ℃ ),immediately and 30 min after restoration of spontaneous heart beat ( T3,T4 ).Arterial O2 content ( CaO2 ),arteriovenous O2 content difference ( Da-jvO2 ),cerebral extraction of O2 ( CEO2 ),arteriovenous glucose and lactate content differences (Da-jvGlu and Da-jvLac) were calculated.Results The Da-jvO2 and CEO2 were significantly decreased at T2 in group D as compared with group C.There was no significant difference in CaO2,Da-jvGlu and Da-jvLac between the 2 groups.Conclusion Dexmedetomidine can reduce cerebral O2 metabolism and help maintain the balance between cerebral O2 supply and demand but has no effect on cerebral glucose metabolism in patients undergoing mitral valve replacement under CPB.