A catheter technique in ophthalmic regional anaesthesia. Cadaver experiments

BACKGROUND: Regional anaesthesia for ophthalmic surgery is generally accomplished by peri- or retrobulbar techniques. Depending on the duration of ophthalmic surgery, reblock might become necessary. Our goal was to invent a catheter technique for ophthalmic regional anaesthesia that enables the user to administer local anaesthetics intraoperatively into the peri- or retrobulbar space continuously. METHODS: Twenty-five adult cadaver orbits of normal size and anatomy were used for the experiments. A flexible catheter was introduced transcutaneously or transconjunctivally into the extra- or intraconal space. Methylene blue solution was injected through the catheter. RESULTS: Using the same transcutaneous retro- and peribulbar technique, it was possible to introduce flexible catheters into a proper position of the cadaver orbits. The injected dye was found intra- or extraconally. CONCLUSION: Examining the spread of the dye in the orbit, we concluded that it is possible to provide ophthalmic anaesthesia for surgery through an indwelling catheter. We proved that continuous or intermittent administration of a local anaesthetic agent into the extra- or inraconal space can be achieved and this technique may allow us to maintain anaesthesia as long as it is necessary.     

A catheter technique in ophthalmic regional anaesthesia. Clinical investigations

BACKGROUND: Usually general anaesthesia is chosen if ophthalmic surgery of longer duration is expected. Our goal was to introduce a flexible catheter preoperatively into the extra- or intraconal space and to provide sufficient anaesthesia by continuous administration of a local anaesthetic via the catheter. METHODS: The continuous anaesthetic technique was applied in 28 patients undergoing vitreoretinal surgery. An indwelling catheter was introduced in 20 patients into the intraconal and in 8 patients into the extraconal space. In 6 patients, the position of the catheter was controlled by ultrasound examination prior to the injection of the local anaesthetic agent. RESULTS: For all patients adequate anaesthesia could be achieved and maintained with continuous retrobulbar administration (CRA) of a local anaesthetic by catheter. There were two patients who experienced moderate pain intraoperatively during continuous peribulbar administration (CPA). No complications occurred with the placement of the catheters. The catheter did not disturb the surgeon or the process of the ophthalmic surgery. CONCLUSIONS: Continuous administration of a local anaesthetic agent via an indwelling catheter into the intraconal space allowed ophthalmic anaesthesia without time restriction. Thus, CRA is a good alternative to general anaesthesia for patients undergoing long-lasting ophthalmic surgery.     

Changes in rapidly extracted auditory evoked potentials during tracheal intubation

BACKGROUND: One of the problems encountered in assessment of the hypnotic level during anesthesia is the extraction of a consistent and reliable measure online and close to real time. Hemodynamic parameters such as heart rate and blood pressure are not, at least with the traditional single parameter versus time presentation, adequate for ensuring an optimal level of anesthesia, especially when using neuromuscular blocking agents (NMBA). In the literature, it has been demonstrated that auditory evoked potentials (AEP) are able to provide two aspects relevant to determining level of anesthesia: firstly, they have identifiable anatomical significance and, secondly, their characteristics reflect the way the brain perceives a stimulus. METHODS: The aim of this study was to evaluate the AEP index based on a system identification model, the autoregressive model with exogenous input (ARX-model), and to compare it to the classical method, the moving time average (MTA). The ARX enables the extraction within 15-25 sweeps, depending on the signal-to-noise ratio (SNR), whereas MTA typically needs 250-500 sweeps. The hypothesis of the present study was that since the ARX-model extracts the AEP faster than the MTA-model, the former should be able to detect changes during the brief, intense stimulus of endotracheal intubation. Twelve female patients scheduled for gynecological surgery were included in the study. Anesthesia was initiated with thiopentone and maintained with isoflurane and alfentanil. The AEP was mapped into an index (AEP-index) normalized to 100 when the individual was awake and decreasing to an average of 25 during thiopentone induced anaesthesia. The results were compared to those obtained by MTA-extracted AEP. RESULTS: During tracheal intubation 9 patients showed an increase in the ARX-extracted AEP-index larger than 15, and 6 of these patients showed an increase larger than 25 (mean increase=33, SD=18). The MTA-extracted AEP-index showed only one patient with an increase larger than 15. The ARX-extracted AEP changed significantly faster than the MTA-extracted AEP. CONCLUSION: The ARX-extracted AEP-index increases during tracheal intubation. There is a significant difference between the ARX-extracted AEP and the traditional MTA-extracted AEP, in terms of response time. In order to trace short-lasting changes in the hypnotic level by AEP, the AEP should be extracted by a method with a fast response such as the ARX-model.     

骶管阻滞麻醉在选择性绿激光前列腺切除术的应用

目的:探讨经尿道选择性绿激光前列腺切除术治疗高危高龄前列腺增生症的简单可行麻醉方法。方法:56例高危高龄前列腺增生症患者,应用2%利多卡因单次骶管阻滞麻醉,施行选择性绿激光前列腺切除术(PVP),采用疼痛分级问卷调查表及根据术中情况判断麻醉效果。结果:除1例患者术中改为硬膜外麻醉外,55例患者在骶管麻醉下成功施行手术,麻醉止痛作用起效时间:5 m in 22例;10 m in 29例;15 m in 4例。麻醉持续时间:60 m in 38例;60~180 m in 17例。疼痛抑制效果满意,麻醉满意评分为:0度48例;I度5例;II度2例。其中4例出现轻微的头晕、心慌、耳鸣等症状,其余未见明显麻醉并发症。结论:单次骶管阻滞麻醉是施行PVP的一种简单、安全和有效的麻醉方法,费用低,使PVP可在门诊完成。     

老人中位硬膜外阻滞初量的推算

目的探讨老人中位硬膜外阻滞初量的个体使用规律。方法≥65岁的中位硬膜外阻滞患者65例,依病人对药物的耐受程度分次注入初量,记录前3次(试验量、分量2、分量3)药量、阻滞平面,计算出相应时点阻滞范围内每个神经节段所需药量,进行相关分析。结果相邻时点前、后阻滞范围内每个神经节段所需药量存在有显著的线性正相关(P<0.01),相关方程依次为y=0.23 1.02x,y=1.61x-0.38。结论老人中位硬膜外阻滞初量的给予中,可依据前次给药时点产生阻滞范围内的每个神经节段所需药量用相关方程推算。     

氯诺昔康复合丙泊酚、芬太尼用于人工流产的临床研究

目的:观察氯诺昔康复合丙泊酚、芬太尼用于无痛人工流产的临床效果.方法:采用双盲法随机将600例早期妊娠妇女分成氯诺昔康组(L组)300例和对照组(P组)300例.麻醉前2h,L组口服氯诺昔康8mg,P组服用安慰剂.麻醉诱导先缓慢静脉注射芬太尼1μg·kg-1,1min后再予丙泊酚1.5mg·kg-1静脉注射.术中根据患者反应每次追加丙泊酚20～30mg.观察记录两组诱导时间、苏醒时间、丙泊酚用药总量、呼吸循环参数改变、术后腹痛发生情况和不良反应.结果:术后腹痛L组少于P组(P＜0.05),术中丙泊酚用药总量L组少于P组(P＜0.05).两组呼吸循环抑制发生率及诱导、苏醒时间差异无显著性(P＞0.05).结论:氯诺昔康用于无痛人工流产可增强麻醉效果,减少丙泊酚用量,减少术后腹痛的发生率,减轻术后腹痛的程度,值得推广应用.     

局部浸润和神经阻滞麻醉在会阴切开中的应用分析

目的 探讨会阴切开时不同麻醉方式对产妇的影响.方法 将100例产妇随机分为左侧阴部神经阻滞麻醉组(阻滞组)和局部组织浸润麻醉组(浸润组),每组50例,比较两组产妇镇痛效果、缝合时间、第四产程出血量及产后72h活动的情况.结果 浸润组在镇痛效果、缝合时间、出血量及产后的活动方面均优于阻滞组.结论 在会阴切开缝合术中应用小剂量利多卡因作阴部浸润麻醉有效减轻了产妇的切口疼痛,缩短缝合时间,减少第四产程出血量.     

表麻下小切口透明晶状体吸出及人工晶状体植入术治疗高度近视

目的 :评价高度近视患者表麻下行透明晶状体吸出及人工晶状体植入术的术后效果。方法 :5 6例 10 6眼高度近视患者在表面麻醉下行小切口透明晶状体吸出及人工晶状体植入术。使用超声乳化仪 ,但未用超声能量。平均年龄 3 8 5 9± 9 44岁 ;术前裸眼视力 0 0 1～ 0 2 ,矫正视力 0 0 5～ 1 0 ;平均近视度 (-19 47± 5 41)D ,平均眼轴长(3 0 45± 1 94)mm ,平均植入人工晶状体屈光度数 ( 3 96± 4 2 7)D。术后平均随访时间 16个月。结果 :术后裸眼视力均好于或等于术前矫正视力。术后裸眼视力≥ 0 5者 79眼 (74 5 % )。术后矫正视力≥ 0 5者 99眼 (93 4% )。术后平均屈光度 (-1 49± 1 11)D。发生后囊膜混浊及玻璃体前界膜混浊 8眼 ,无视网膜脱离及黄斑囊样水肿发生。结论 :表麻下小切口透明晶状体吸出及人工晶状体植入术矫正高度近视 ,安全有效 ,预测性好 ,视力稳定。