High dose dexmedetomidine as the sole sedative for pediatric MRI

Objective: This large-scale retrospective review evaluates the sedation profile of dexmedetomidine. Aim: To determine the hemodynamic responses, efficacy and adverse events associated with the use of high dose dexmedetomidine as the sole sedative for magnetic resonance imaging (MRI) studies. Background: Dexmedetomidine has been used at our institution since 2005 to provide sedation for pediatric radiological imaging studies. Over time, an effective protocol utilizing high dose dexmedetomidine as the sole sedative agent has evolved. Methods/Materials: As part of the ongoing Quality Assurance process, data on all sedations are reviewed monthly and protocols modified as needed. Data were analyzed from all 747 consecutive patients who received dexmedetomidine for MRI sedation from April 2005 to April 2007. Results: Since 2005, the 10-min loading dose of our dexmedetomidine protocol increased from 2 to 3 μg·kg⁻¹, and the infusion rate increased from 1 to 1.5 to 2 μg·kg⁻¹·h⁻¹. The current sedation protocol progressively increased the rate of successful sedation (able to complete the imaging study) when using dexmedetomidine alone from 91.8% to 97.6% (P = 0.009), reducing the requirement for adjuvant pentobarbital in the event of sedation failure with dexmedetomidine alone and decreased the mean recovery time by 10 min (P < 0.001). Although dexmedetomidine sedation was associated with a 16% incidence of bradycardia, all concomitant mean arterial blood pressures were within 20% of age-adjusted normal range and oxygen saturations were 95% or higher. Conclusion: Dexmedetomidine in high doses provides adequate sedation for pediatric MRI studies. While use of high dose dexmedetomidine is associated with decreases in heart rate and blood pressure outside the established ‘awake’ norms, this deviation is generally within 20% of norms, and is not associated with adverse sequelae. Dexmedetomidine is useful as the sole sedative for pediatric MRI.     

Hemodynamic effects of dexmedetomidine sedation for CT imaging studies

Background: Dexmedetomidine sedation for radiological imaging studies is a relatively recent application for this drug. Previous studies have demonstrated some haemodynamic effects of dexmedetomidine, however, the effects remain poorly described in children. The aim of this study was to better define the effect of age on heart rate (HR) and blood pressure changes in children sedated for CT imaging with dexmedetomidine. Methods/materials: At our institution dexmedetomidine is given for sedation for CT imaging as a bolus of 2 mcg·kg⁻¹ over 10 min followed by an infusion of 1 mcg·kg⁻¹·h⁻¹ with a second bolus if required. Detailed quality assurance data sheets document patient demographics, sedation outcomes, adverse events, and hemodynamic data are recorded for each patient. Results: A total of 250 patients (range 0.1–10.6 years) received dexmedetomidine. anova revealed strong evidence for changes in HR and mean arterial blood pressure during bolus and infusion relative to presedation values (P < 0.001). These changes were apparent in each age group and similar between groups. During the first bolus and during infusion, 82% and 93% of patients respectively were within the age-based normal range for HR. For mean arterial blood pressure, 70% of patients were within the normal range during first bolus and 78% during infusion. Conclusion: In the pediatric population studied, intravenous dexmedetomidine sedation was associated with modest fluctuations in HR and blood pressure. Hemodynamic changes were independent of age, required no pharmacologic interventions and did not result in any adverse events. By anticipating these possible hemodynamic effects and avoiding dexmedetomidine in those patients who may not tolerate such fluctuations in HR and blood pressure, dexmedetomidine is an appropriate sedative for children undergoing CT imaging.     

Nrf2-GPX4介导的铁死亡通路参与右美托咪定对脑出血大鼠神经保护作用的机制研究

目的 探究核因子E2相关因子2/谷胱甘肽过氧化物酶4（Nrf2-GPX4）介导的铁死亡通路参与右美托咪定（Dex）对脑出血（ICH）大鼠发挥神经保护作用的机制。方法 将100只SD大鼠按随机数字表法分为Sham组、ICH组（模型组）、Dex-L组（Dex 50 μg/kg）、Dex-H组（Dex 100 μg/kg）、...     

Dexmedetomidine for the treatment of postanesthesia shivering in children

BACKGROUND: Shivering is a common postanesthesia adverse event with multiple etiologies and multiple suggested prophylactic and abortive treatment regimens. Dexmedetomidine, a centrally acting alpha(2)-adrenergic agonist, has been used as a sedative agent and is known to reduce the shivering threshold. We hypothesized that children with postanesthesia shivering would reduce shivering behavior following a single bolus dose of dexmedetomidine. METHODS: Dexmedetomidine was administered in a prospective, open-label fashion. The anesthesia management was uniform consisting of maintenance inhaled anesthesia (sevoflurane) and the intraoperative administration of fentanyl (1-2 microg.kg(-1)) plus a regional anesthetic technique (either a neuraxial or peripheral block) for postoperative analgesia. Criteria for treatment included: (i) shivering, (ii) successful extubation, and (iii) no other complaint/indication of pain. All children who met the criteria were treated with a single intravenous bolus dose of dexmedetomidine (0.5 microg.kg(-1)) over 3-5 min. Following the completion of drug administration, shivering activity was recorded every minute (up to 10 min) with any adverse effects or complaints. The efficacy of shivering reduction at 5 min in this cohort is compared with previous reports from the literature of the efficacy of clonidine and meperidine. RESULTS: Twenty-four children ranging in age from 7 to 16 years (11.5 +/- 2.5 years) were treated. All children had a cessation of shivering behavior within 5 min following the completion of dexmedetomidine administration. The onset of effect was 3.5 +/- 0.9 min. No adverse effects were observed. No shivering behavior recurred. CONCLUSIONS: This study demonstrates the efficacy of dexmedetomidine in the treatment of postanesthesia shivering.     

Initial experience with dexmedetomidine for diagnostic and interventional cardiac catheterization in children

BACKGROUND: Children undergoing diagnostic and interventional cardiac catheterization require deep sedation or general anesthesia (GA). Dexmedetomidine, a selective alpha-2 adrenergic agonist, has sedative, analgesic and anxiolytic properties without respiratory depression. These characteristics make it potentially suitable as a sedative agent during diagnostic procedures in children. We report our experience using dexmedetomidine in 20 children aged 3 months to 10 years undergoing cardiac catheterization. METHODS: Following a midazolam premedication, intravenous access was secured facilitated by the inhalation of sevoflurane in oxygen. A loading dose of 1 microg x kg(-1) dexmedetomidine was administered over 10 min followed by an initial infusion rate of 1 microg x kg(-1) x h(-1). Nasal cannulae were applied, allowing endtidal CO2 monitoring with the patients breathing spontaneously. Hemodynamic parameters, Bispectral Index Score (BIS) and sedation score were measured every 5 min. Patient movement or evidence of inadequate sedation were treated with propofol (1 mg x kg(-1)). The dexmedetomidine infusion rate was titrated to the level of sedation to a maximum of 2 microg x kg(-1) x h(-1) to maintain a sedation score of 4-5 and a BIS value <80. RESULTS: Five patients (25%) had some movement on local infiltration or groin vessel access. This did not necessitate restraint or result in difficulty securing vascular access. No patients failed sedation that required the addition of another sedative agent or conversion to GA; eight patients were sedated with dexmedetomidine alone; however, 12 (60%) patients did receive a propofol bolus at some time during the procedure due to movement, increasing BIS value or in anticipation of stimulation. There were no incidences of airway obstruction or respiratory depression. In all cases the heart rate and blood pressure remained within 20% of baseline. No patient required treatment for profound bradycardia or hypotension. The average infusion rate for dexmedetomidine following the loading dose was 1.15 (+/-0.29)microg x kg(-1) x h(-1) (range 0.6-2.0 microg x kg(-1) x h(-1)). CONCLUSIONS: This initial experience showed dexmedetomidine, with or without the addition of propofol, may be a suitable alternative for sedation in spontaneously breathing patients undergoing cardiac catheterization.     

盐酸右美托咪定在妊娠期高血压高龄产妇剖宫产围术期应用效果研究

目的 观察右美托咪定是否可以增加妊娠期高血压高龄产妇剖宫产术中术后镇痛、镇静程度,维持血流动力学稳定,减轻围术期炎症反应和氧化应激损伤。 方法 选择接受剖宫产手术的高龄且合并妊娠期高血压疾病的产妇60例,分为右美托咪定组（D组）和对照组（C组）,每组30例。D组产妇在胎儿娩出并切断脐静脉后给予盐酸右美托咪定（负荷量0.5 μg/kg,维持量0.2 μg·kg-1·h-1持续泵注至术毕）,C组以同样的方法给予等容量生理盐水。手术结束后连接静脉自控镇痛泵,D组：右美托咪定2 μg/kg+舒芬太尼2 μg/kg+地佐辛0.3 mg/kg+托烷司琼10 mg+盐水共100 mL;C组：舒芬太尼2 μg/kg+地佐辛0.3 mg/kg+托烷司琼10 mg+盐水共100 mL。采集以下指标：术前（T1）、给药后20 min（T2）、术毕（T3）,术后6 h（T4）、24 h（T5）、48 h（T6）Ramsay镇静程度评分、视觉模拟评分（visual analogue scale,VAS）;术后镇痛泵按压次数;T1~T6血流动力学参数;不良反应发生率;炎症反应及氧化应激指标：T1~T6静脉血肿瘤坏死因子α（tumor necrosis factor-α,TNF-α）、白细胞介素6（interleukin-6,IL-6）、丙二醛（malondialdehyde,MDA）和超氧化物歧化酶（superoxide dismutase,SOD）浓度。 结果 D组T2~T6时Ramsay镇静评分明显高于C组,T4~T6时VAS疼痛评分明显低于C组（P＜0.05）;D组术后镇痛泵按压次数明显低于C组（P＜0.05）。D组T2~T6时收缩压、舒张压、心率明显低于C组（P＜0.05）。不良反应发生率两组比较差异无统计学意义（P＞0.05）。D组T2~T6时TNF-α、IL-6、MDA水平明显低于C组,SOD水平明显高于C组（P＜0.05）。 结论 右美托咪定可以维持妊娠期高血压高龄产妇围手术期血流动力学的稳定,减轻紧张焦虑及疼痛程度,并通过镇痛镇静作用减少炎症反应和氧化应激反应,改善预后。     

右美托咪啶对地氟醚麻醉期间血浆中去甲肾上腺素和

目的 观察右美托咪啶对地氟醚麻醉期间血浆中去甲肾上腺素和肾上腺素水平的影响。 方法 回顾性分析ASA Ⅰ～Ⅱ级择期行腹腔镜下子宫次全切除手术60例病人,分为对照组（地氟醚组）和联合组（右美托咪啶与地氟醚联合麻醉组）,每组30例。两组术前和诱导用药相同,联合组麻醉诱导后开始每小时静脉输注右美托咪啶0.5 μg/kg并维持至麻醉结束。对照组在麻醉诱导后静脉注射给予相同体积的生理盐水。于麻醉诱导前（T₀）、吸入地氟醚30 min后（T₁）、手术开始后60 min（T₂）及关腹膜后即刻（T₃）分别抽取中心静脉血,测定血浆肾上腺素（EP）和去甲肾上腺素（NE）浓度;观察心率（HR）、平均动脉压（MAP）和呼吸恢复、拔管时间、术中知晓发生率以及苏醒期躁动评分。 结果 与T₀比,两组T₁、T₂和T₃ EP和NE水平明显升高（P<0.05）;与对照组比较,联合组T1、T2和T3 EP和NE水平明显降低（P<0.05）,HR减慢、MAP降低、呼吸恢复时间、拔管时间缩短（P<0.05）,苏醒期躁动的评分减低（P<0.05）。 结论 右美托咪啶可以降低地氟醚麻醉期间血浆中去甲肾上腺素和肾上腺素水平。     

Intramuscular dexmedetomidine premedication—an alternative to midazolam-fentanyl-combination in elective hysterectomy?

Sedation, anxiolysis, intubation responses and fentanyl anaesthetic requirements were investigated in a double-blind, randomized study in twenty ASA I-II elective hysterectomy patients. Ten patients received dexmedetomidine 2.5 μg kg^-1 i.m. 60 min before induction and saline placebo i.v. 2 min prior to induction (= DP group). Ten patients received midazolam 0.08 mg kg^-1 i.m. 60 min and fentanyl 1.5 μg kg^-1 i.v. (= MF group) 2 min before induction of anaesthesia with thiopentone 4 mg kg^-1. Anaesthesia was maintained with 70% nitrous oxide in oxygen and with fentanyl 2 μg kg^-1 i.v. increments according to predetermined criteria. Both premedications induced sedation ( P < 0.01 in both groups) and anxiolysis ( P < 0.01 in DP vs <0.05 in MF group) without any differences between the groups. Haemodynamic changes following tracheal intubation did not significantly differ between the groups. Intraoperatively systolic and diastolic arterial pressure were 15% and 13% lower in DP group ( P < 0.01 and P < 0.05 for drug effect), the mean heart rate was approximately 9 beats min^-1 lower in DP group (n.s.). Fentanyl was required more often in MF group: median 3.5 (QD 1.5) vs. 2.5 (QD 0.5) times in DP group ( P < 0.05), the total amount being 57% smaller in DP group: 0.03 (QD 0.01) vs. 0.07 (QD 0.02) μg kg^-1 min^-1 ( P < 0.05). Postoperative course and analgesic requirements were similar in both groups. Dexmedetomidine premedication may offer an alternative to current anaesthesia practice in elective hysterectomy.     

右美托咪定滴鼻用于小儿腹腔镜疝囊高位结扎术的临床观察

目的探讨不同剂量右美托咪定（dexmedetomidine, Dex)滴鼻对腹腔镜疝囊高位结扎术小儿的影响。方法选取90例拟行腹腔镜疝囊高位结扎术患儿,随机分为3组（A组、B组和C组）,每组30例。麻醉诱导前30min,A组经鼻滴入右美托咪定（1μg/kg）,B组经鼻滴入右美托咪定（2μg/kg）,C组为经鼻滴入等量生理盐水。记录患儿滴鼻前即刻（T0）、滴鼻后10min（T1）、滴鼻后20min（T2）、麻醉诱导时（T3）、手术开始时（T4）、拔出喉罩时（T5）的心率（heart rate, HR)、平均动脉压（mean arterial pressure, MAP)和血氧饱和度(saturation pulse oxygen, SpO2),以及麻醉时间、手术时间、诱导期合作表（induction compliance checklist, ICC)评分、儿童苏醒期躁动量表（pediatric anesthesia emergence delirium, PAED）评分、出院后行为问卷（post hospitalization behavior questionnaire, PHBQ）例数和不良反应的发生。结果与A组、C组相比,B组T2、T4、T5时MAP,T2～T5时HR显著下降（P<0.05）。与C组相比,A组和B组ICC评分、PAED评分、PHBQ例数显著下降（P<0.05）。三组患儿一般资料、麻醉时间、手术时间、SpO2及不良反应发生的差异无统计学意义。结论右美托咪定滴鼻用于小儿腹腔镜疝囊高位结扎术,可显著提高麻醉诱导合作度,降低苏醒期躁动和出院后行为改变的发生。术前滴鼻右美托咪定1μg/kg与2μg/kg对MAP和HR影响较小。