Clinical experience with minimal flow xenon anesthesia

Xenon is a more potent anesthetic than nitrous oxide, and gives more profound analgesia. This investigation was performed to assess the potential of xenon for becoming an anesthetic inspite of its high manufacturing cost. Seven ASA I—-II patients undergoing cholecystectomy (n = 4), hernia repair (n = 2), or mammoplasty (n=l) were studied. Denitrogenation by 15–20 min of oxygen breathing under propofol anesthesia was followed by fentanyl–supplemented xenon anesthesia administered via an automatic minimal flow system which held the oxygen concentration at 30%. Xenon anesthesia lasted 76–228 min and 8–14 1 of xenon (ATPD) was used, of which 5.6–8.1 1 was expended during the first 15 min. Anesthesia appeared to be satisfactory, and the patients woke up rapidly after xenon was discontinued. The automatic system made minimal flow xenon anesthesia easy to administer, but nitrogen accumulation is still a problem. Assuming a xenon price of 10 US $ per litre, the average cost for xenon was about 65 US $ for the first 15 min and then about 25 USS for each subsequent hour of anesthesia.     

化工废水中N-亚硝基二正丙胺的吹扫捕集-GC-MS测定法

目的建立简单快速提取并测定N-亚硝基二正丙胺(NDPA)的方法。方法采用Trap3捕集管,利用标准吹扫捕集程序(吹扫气体流速40ml/min,吹扫时间11min,解吸温度225℃,解吸时间4min,烘烤温度230℃,烘烤时间10min),有效富集了化工废水中μg/L级的NDPA,建立了吹扫捕集(P&T)气相色谱质谱联用(GC-MS)化学源(CI)选择离子模式(uSIS)快速、准确分析废水中NDPA的分析方法。结果方法的相对标准偏差为7.5%;废水的加标回收率在62.60%～96.31%;在5～30μg/L范围内线性良好,线性回归系数为0.978;方法的最低检出限为3μg/L。结论采用P&T-GC-MS/CI/uSIS法可用于化工废水中半挥发性有机物NDPA的测定。     

静注加肌注曲马多防治硬膜外麻醉期间寒战反应的研究

目的　观察曲马多防治硬膜外麻醉期间寒战反应时两种用药方法的临床效果。　方法硬膜外麻醉手术期间发生寒战的 6 0例成年患者 ,当出现寒战分级达 2～ 3级时 ,用室温下盐酸曲马多 1mg kg加氟哌啶 2 .5mg缓慢静脉推注 ,随机分成二组 :研究组 (R组 )与对照组 (C组 ) ,每组各 30例 ;R组在 5min内用上述同样药物和剂量予以肌内注射 ,C组以生理盐水 2ml肌内注射。观察寒战的治疗效果及 6h内寒战复发率。　结果　两组均于静注曲马多后 3min内起效 ,所有病人寒战反应均得到缓解 ,6h内R组均无寒战反应复发 ,C组有 5例再次出现寒战达 2级以上 ,给予追加首次量的 1 2后缓解 ,两组间差异有显著性 (P <0 .0 5 )。　结论　静注加肌注曲马多和氟哌啶可更有效地防治硬膜外麻醉期间的寒战反应。     

控制性降压在鼻内窥镜手术中的应用

目的 :观察控制性降压在鼻内窥镜手术中应用的意义。方法 :80例双侧鼻息肉、鼻窦炎患者 ,局麻、鼻内窥镜下行双侧鼻息肉摘除、全筛切除及开放上颌窦自然开口。其中 38例术中控制性降压 (降压组 ) ,另 42例作为对照。结果 :降压组术中出血 (6 1 39± 38 5 2 )ml,对照组出血 (140 12± 81 82 )ml,差异有显著性意义 (P <0 0 1) ;手术时间分别为 (4 9 2 5± 7 0 6 )min和(6 2 4 0± 9 90 )min ,差异有显著性意义 (P <0 0 1)。结论 :控制性降压可明显减少术中出血 ,缩短手术时间。     

经面罩机械通气治疗急性肺水肿的疗效观察

目的 研究经面罩机械通气(FMMV)对急性肺水肿的治疗效果。方法 34例肺水肿患者,分为对照组12例,采用常规治疗;治疗组22例,在常规治疗的基础上或常规治疗效果不佳的情况下给予FMMV,观察临床表现、胸部X线片和动脉血气的变化。结果 FMMV后30min内,91％的患者能较好耐受,所有患者呼吸困难皆明显改善,呼吸频率由(37±7)次/min降至(26±5)次/min(P<0.05),心率由(122±21)次/min降至(94±27)次/min(P<0.05),4例(18％)低血压患者血压迅速回升。77％的患者24h内咳嗽、咳痰和肺部湿啰音基本缓解。临床症状的总体好转速度治疗组明显高于对照组。吸氧流量相同的情况下,治疗组1h后PaO_2由(62±10)mm Hg升至(78±18)mm Hg(P<0.05),2～6h后升至(96±22)mm Hg(P<0.05),PaO_2升高的速度和幅度皆较对照组显著;脱机时,治疗组在吸空气条件下PaO_2维持在(79±8)mm Hg(P<0.05),PaCO_2和pH也逐渐恢复正常。95％的患者在24～48h内脱离呼吸机。结论 与常规治疗相比,FMMV可迅速改善心功能,并更快改善肺水肿和低氧血症。     

Transfer of clonidine and dexmedetomidine across the isolated perfused human placenta

Background: The placental transfer of the a₂ receptor agonist clonidine, earlier used as an adjuvant in obstetric epidural analgesia, was compared with the transfer of the newer and more %-selective agonist dexmedetomidine.
Methods: Term placentas were obtained immediately after delivery with maternal consent and a 2-hour recycling perfusion of a single placental cotyledon was performed. Disappearance from the maternal circulation, accumulation in placental tissue and appearance in the fetal circulation of clonidine or dexmedetomidine with the reference compound antipyrine were followed in 4 experiments for both drugs.
Results: At 2 hours the percent dexmedetomidine found in the fetal circulation was 12.5 (SD 5.1)%, while 48.1 (SD 20.3)% was found in the perfused placental cotyledon. A higher mean clonidine than dexmedetomidine concentration was achieved in the fetal circulation (1.90 vs. 0.56 nmol/l, P <0.05). At 2 hours the percent clonidine found in the fetal circulation was 22.1 (SD 2.4)% ( P <0.05), while 11.3 (SD 3.3)% ( P <0.05) was re tained in the perfused placental cotyledon. The transfer indexes, describing maternal-to-fetal transfer of dexmedetomidine and clonidine normalized with the transfer of antipyrine, were 0.88 (SD 0.07) and 1.04 (SD 0.08) respectively ( P <0.05).
Conclusions: Dexmedetomidine disappeared faster than clonidine from the maternal circulation, while even less dexmedetomidine was transported into the fetal circulation. This was due to its greater placental tissue retention, the basis for which probably is the higher lipophilicity of dexmedetomidine.     

Should nitrous oxide be discontinued before desflurane after anaesthesia with desflurane/N2O?

Background : The appearance of hypoxaemia immediately after anaesthesia with nitrous oxide may be partially explained by diffusion hypoxia. This study was undertaken to evaluate circulatory and respiratory variables during emergence after desflurane/nitrous oxide anaesthesia, and whether there are any differences depending on which gas is discontinued first. Methods : 20 patients were studied after gynaecological laparoscopic surgery. The depth of anaesthesia was reduced 10 min prior to the emergence by stopping the administration of one of the two inhalational agents. Desflurane was discontinued first in Group 1, nitrous oxide in Group 2. Ventilation was controlled with E'C0₂ maintained at 5% until the administration of the second anaesthetic gas was discontinued. Thereafter, the patients breathed spontaneously. Results : The PaC0₂ at which the respiratory drive reappeared after controlled normoventilation was similar in both groups, 6.1–6.5 kPa, and extubation was performed after 10–11 min. At extubarion, the end–tidal C0₂ and total MAC were similar in the groups, about 6.2 vol% and 0.16, respectively. Mean arterial blood pressure was significantly higher in Group 1. The cardiac output increased in both groups from about 6 1/min at the conclusion of anaesthesia to 9.0 and 7.6 1/min at 15 min in the recovery period. End–tidal O₂ decreased and CO₂ increased in both groups during the first 10 min in the recovery period. pH was reduced at 15 and 30 min in both groups. Conclusion : Irrespective of which agent was discontinued first, there was an increase in cardiac output, decrease in oxygenation and a modest acidosis in the first 30–min recovery period. The only significant difference between the groups was in mean arterial blood pressure in the early emergence phase with a greater MAP when N₂O had been used until the conclusion of anaesthesia.     

Scintigraphic visualization of intrathecal liposome biodistribution

Background: Liposomes containing local anaesthetics have been administered intrathecally and in the epidural space. Poor attention has been given to the pharmacokinetics of liposomes as drug carriers. Therefore, we observed the biodistribution of liposomes after intrathecal injection in rats by scintigraphic imaging during 24 h.
Methods: We administered ⁹⁹Tc-labeled multilamellar (MLV) and small unilamellar vesicles (SUV) of defined size and volume dispersities into the cerebrospinal fluid at the lumbar level. Those vesicles were free of contamination by radiolabeled colloids as visualized by light and electron microscopy and of neurotoxic products from phosphatidylcholine hydrolysis and peroxidation, both during the preparation process and after 24 h incubation in cerebrospinal fluid at 37°C in vitro.
Results: SUV immediately diffused from the lumbar site of injection to the head and were cleared between 1 and 24 h after injection. MLV were cleared more slowly from the spinal space and appeared in the head region 1 h after injection where they accumulated up to 24 h. These differences were explained in terms of vesicle sizes and volumes. SUV with 0.05 μm diameters were rapidly absorbed into the blood through the arachnoid granulations. In contrast, particles larger than the upper size limit of the arachnoid granulations permeability (±8 μm) could accumulate in the head with a slow elimination rate.
Conclusion: This difference in clearance from the intrathecal space outlines the importance of defining the size of the liposomes, the distribution of a tracer or a drug inside the liposomal preparation, the chemical stability and the absence of toxic degradation products of liposome formulations before clinical use.     

代氟醚和安氟醚低流量循环密闭吸入全麻的临床观察

使用低流量循环密闭回路内注入给药法，比较１ＭＡＣ代氟醚和安氟醚各１４例维持全麻时循环动力苏醒情况和不良反应。结果；代氟醚在维持阶段对心血管系统的抑制较安氟醚为轻，很可能和代氟醚能使交感神经兴奋性增加有关。     

硬膜外注入异氟醚－氧化亚氮气体增强利多卡因麻醉作用

我们对５０例子宫、卵巢手术病人，使用利多卡因做硬膜外麻醉，其中２５例向硬膜外腔内注入异氟醚－氧化亚氮气体。２组对比发现，实验组麻醉平面明显高于对照组，在同样手术时间内实验组所使用的利多卡因量明显少于对照组。表明异氟醚－氧化亚氮气体有增强利多卡因的硬膜外麻醉作用，同时未发现注入吸入麻醉药产生副作用。