下肢手术患者右美托咪定和咪达唑仑扩张外周血管作用的程度

Degree of peripheral vasodilation induced by dexmedetomidine and midazolam in patients undergoing lower extremity surgery

目的 确定下肢手术患者右美托咪定和咪达唑仑扩张外周血管作用的程度.方法 择期硬膜外麻醉下行下肢手术患者100例,性别不限,年龄27～64岁,BMI 20 ～30 kg/m2,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,分为4组（n=25）：右美托咪定组（D组）、补偿性扩容＋右美托咪定组（CVE＋D组）、眯达唑仑组（M组）和补偿性扩容＋咪达唑仑组（CVE＋M组）.D组和CVE＋D组经5 min静脉输注右美托咪定负荷剂量0.5 μg/kg,随后以0.3～0.6 μg· kg-1·h-1速率输注;M组和CVE＋M组经5 min静脉输注咪达唑仑0.05 mg/kg,随后以0.03～0.10 μg＆· kg-1·h-1速率输注,4组均输注至警觉/镇静评分达到3分.CVE＋D组和CVE＋M组在输注右美托咪定和咪达唑仑的同时开始补偿性扩容,静脉输注6％羟乙基淀粉130/0.4氯化钠溶液0.5 ml·kg-1·min-1,输注剂量7 ml/kg.分别于输注右美托咪定或咪达唑仑前和警觉/镇静评分达到3分时采集动脉血样,测定血糖浓度,然后静脉注射50％葡萄糖10 ml,注射后3 min时再次采集动脉血样,测定血糖浓度,根据葡萄糖初始分布容积确定葡萄糖稀释程度,以反映扩张外周血管程度.结果 D组、CVE＋D组、M组和CVE＋M组扩张外周血管程度分别为（8.5±0.5）％、（8.4±0.4）％、（0.9±0.5）％和（0.8±0.5）％,D组和CVE＋D组间及M组和CVE＋M组间扩张外周血管程度比较差异无统计学意义（P＞0.05）.结论 下肢手术患者右美托咪定扩张外周血管的程度约为8.5％,咪达唑仑扩张外周血管的程度仅约为0.9％.

Objective To evaluate the degree of peripheral vasodilation induced by dexmedetomidine and midazolam in the patients undergoing lower extremity surgery.Methods One hundred patients of both sexes, aged 27-64 yr, with body mass index of 20-30 kg/m2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ , undergoing elective lower extremity surgery under epidural anesthesia, were randomly divided into 4 groups （n =25 each） ： dexmedetomidine group （group D）, compensatory volume expansion＋dexmedetomidine group （group CVE＋D）, midazolam group （group M） , and compensatory volume expansion ＋ midazolam group （group CVE＋M）.In D and CVE＋D groups, dexmedetomidine was infused over 5 min in a loading dose of 0.5 μg/kg, followed by an infusion of 0.3-0.6 μg· kg-1 · h-1 until Observer＆#39;s Assessment of Alertness/Sedation （OAA/S） score reached 3.In M and CVE＋M groups, midazolam was injected over 5 min in a dose of 0.05 mg/kg, followed by an infusion of 0.03-0.10 μg · kg-1 · h-1 until OAA/S score reached 3.In CVE＋D and CVE＋M groups, compensatory volume expansion was performed at the same time as dexmedetomidine and midazolam were infused, 6% hydroxyethyl starch 130/0.4 and sodium chloride solution was infused intravenously at a rate of 0.5 ml · kg-1 · min-1, and the total volume infused was 7 ml/kg.Before injection of dexmedetomidine or midazolam, and when OAA/S score reached 3, arterial blood samples were collected to determine the blood glucose concentration.Then 50% glucose 10 ml was injected intravenously, and 3 min later, arterial blood samples were collected again to determine the blood glucose concentration.According to the initial distribution volume of glucose, the degree of glucose dilution was determined to reflect the degree of peripheral vasodilation.Results The degree of peripheral vasodilation was （8.5±0.5）%, （8.4±0.4） %,（0.9±0.5）% and （0.8±0.5）% in D, CVE＋D, M and CVE＋M groups, respectively.There was no significant difference in the degree of peripheral vasodilation between D and CVE＋D groups, and between M and CVE＋M groups.Conclusion The degree of peripheral vasodilation induced by dexmedetomidine is about 8.5%, and by midazolam is only about 0.9% in the patients undergoing lower extremity surgery.