椎管内麻醉 Neuraxial Anesthesia 夏 瑞

Introduction——Correlated Anatomy 三条韧带(由外到内) 棘上韧带 supraspinous ligament 棘间韧带 interspinous ligament 黄韧带 ligamentum flavum (yellow ligament)

Correlated Anatomy 脊髓由脊膜所包裹 脊膜(由内至外)分为： 硬膜外腔 epidural space 软膜 pia mater 蛛网膜 arachnoid mater 硬脊膜 dura mater 两层：内膜、外膜 硬膜外腔 epidural space 硬脊膜内、外层之间的区域 蛛网膜下腔subarachnoid space 软膜和蛛网膜之间的区域

Correlated Anatomy

Classification of Neuraxial Anesthesia 蛛网膜下腔阻滞麻醉 Spinal Anesthesia 硬膜外腔阻滞麻醉 Epidural Anesthesia 蛛网膜下腔与硬膜外腔联合阻滞麻醉 Combined spinal-epidural Anesthesia ,CSEA 骶管阻滞麻醉 Caudal Anesthesia

第一节 蛛 网 膜 下 腔 阻 滞（脊麻) Section one Subarachnoid block (spinal anesthesia) 一、概述(outline) 定义（definition） The agent is injected into the CSF(cerebrospinal fluid) in the subarachnoid space of the meninges (the three-layered covering of the spinal cord) using a lumbar interspace in the vertebral column. 局麻药 脑脊液 脊神经、背根神经节及脊髓表面

第一节 蛛 网 膜 下 腔 阻 滞 Section one Subarachnoid block (spinal anesthesia) 概述(outline) 比重：According to the differences of gravity between the local anesthetic and CSF Hyperbaric solution: It is heavier than CSF,and it can be made (重比重) by the addition of glucose. Hypobaric solution: It is lighter than CSF,and it can be made (轻比重) 　 by the addition of sterile water. Isobaric solution: It is nearly equal to gravity of CSF, and it is (等比重) mixed with CSF(at least 1:1). (The gravity of CSF is 1.003～1.009)

平面：According to the level of neural blockade 一、概述(outline) 平面：According to the level of neural blockade high position: The sensory blockade ＞T4 Spinal anesthesia mid position: The sensory blockade≤T5—9 low position: The sensory blockade＜T10. “saddle block” means that the level of neural blockade is limited to perineum(会阴) or hip (臀部). (鞍麻） “Unilateral block” means that the level of neural blockade is limited to unilateral lower extremity (单侧阻滞)

Autonomic Nf* sensory Nf motor Nf 二、蛛网膜下隙阻滞的机制及其对生理的影响 (The mechanism of action and physiologic responses) 1. 直接作用 (Direct actions) : ▲The site of action: The principal site of action is the nerve root. ▲ The sequence of block: Autonomic Nf* sensory Nf motor Nf myelinated Ar Nf * Nf: nerve fiber (有髓鞘的本体感觉纤维) ▲ The differential level of block: Sympathetic block may be 2-4 segments higher than sensory block, which in turn is 1-4 segments higher than motor block.

Indirect actions(systemic effects) 2. 间接作用(全身影响): Indirect actions(systemic effects) ★ Cardiovascular manifestations——心血管系统影响 vasodilation of venous capacitance vessels capacity of venous return to heart Sympathetic Nf block arterial vasodilation BP systemic vascular resistance sympathetic cardiac accelarator fibers block HR

Indirect actions(systemic effects) ★ Pulmonary manifestations（呼吸系统影响） Tidal volume remains unchanged during high spinal anesthesia, and vital capacity decreases a small amount from 4.05 to 3.73 L 潮气量改变不明显,肺活量少量下降 The rare respiratory arrest associated with spinal anesthesia is also unrelated to phrenic or inspiratory dysfunction but rather to hypoperfusion of the respiratory centers in the brainstem 呼吸暂停与脑干呼吸中枢血流灌注不足有关，与呼吸肌功能无关

★ Gastrointestinal manifestations(胃肠道影响） Spinal block sympathetic block vagal tone a contracted gut with active peristasis （内脏收缩，蠕动 ） ★Urinary tract manifestations（泌尿系统影响） Renal blood flow is maintained through autoregulation, and there is little clinical effect on renal function from spinal block. 肾功能影响小

三、蛛网膜下腔阻滞的临床应用 (一)适应证(indications)： 下腹部手术，如：阑尾切除术、疝修补术 肛门及会阴部手术，如：痔切除术 (The clinical applications of subarachnoid block) (一)适应证(indications)： 下腹部手术，如：阑尾切除术、疝修补术 肛门及会阴部手术，如：痔切除术 盆腔手术，如：子宫切除、膀胱手术 下肢手术，如：截肢手术

( 二) 禁忌证(contraindications) Absolute   contraindications Infection at the site of injection  Patient refusal   Coagulopathy or other bleeding diathesis Severe hypovolemia  Increased intracranial pressure   Severe aortic stenosis   Severe mitral stenosis

( 二) 禁忌证(contraindications) Relative    contraindications Sepsis   Uncooperative patient  Preexisting neurological deficits     Demyelinating lesions   Stenotic valvular heart lesions   Severe spinal deformity

( 二) 禁忌证(contraindications) Controversial     contraindications  Prior back surgery at the site of injection   Inability to communicate with patient    Complicated surgery     Major blood loss     Maneuvers that compromise respiration Prolonged operation

（三）麻醉前准备 preanesthetic preparation Equipment Respirator Monitor Oxygen drugs Local anesthetic vasoactive agent

(四)常用局麻药： (Commonly used spinal anesthetic agents) ▲Procaine：procaine 150mg+csf2.7ml or + 5%G.S 2.7ml+0.1%Adr0.3ml. ▲Dicaine: 最常用重比重液（1-1-1溶液）: 1%Dicaine 1ml+3-5% Ephedrine 1ml+10%G.S 1ml： 即: 0.33%Dicaine（10-15mg) ▲Bupivacaine：常用重比重液： 0.75% Bupivacaine 2ml+10%GS 1ml 常用8-12mg

(五)蛛网膜下腔穿刺术: ●体位(Patient position): ( Performing a lumbar puncture) ●体位(Patient position): ★Sitting position: ★Lateral decubitus ★Prone position: ●定位(Identification of lumbar interspaces): A line drawn between both iliac crests usually crosses either the body of L4 or the L3-4 interspace. ●穿刺间隙(Lumbar interspace of penetration): L3-4. Performing a lumbar puncture below L1 in adults or L3 in children avoids needle trauma to the cord.

●穿刺方法(approachs): 直入法 midline approach 侧入法 para-midline approach The midline approach is the technique of first choice because it requires anatomic projection in only two planes and provides a relatively avascular plane. 侧入法 para-midline approach When difficulty in needle insertion is encountered with the midline approach, one option is to use the paramedian route, which does not require the same level of patient cooperation and reversal of lumbar lordosis for success.

(六)阻滞平面的调节 (regulating the level of blockade) 阻滞平面指皮肤感觉消失的界限 The level of sensory blockade can be assessed With pinprick. The motor blockade is two segments lower than the sensory blockade. 麻醉药注入蛛网膜下隙后，要在短时间内主动调节 和控制麻醉平面，达手术所需范围，但应避免平面 过高。

factors postulates to be related to spinal anesthetic block height ★麻醉平面的影响因素 factors postulates to be related to spinal anesthetic block height 穿刺间隙 药物种类、浓度、剂量及比重 注药速度、针口方向 病人特征 Patient characteristics

Factors Postulated to be Related to Spinal Anesthetic Block Height Characteristics of anesthetic solution Density Amount (mass) Concentration Temperature Volume Vasoconstrictors

Factors Postulated to be Related to Spinal Anesthetic Block Height Technique of injection Site of injection Direction of injection (needle) Direction of bevel Use of barbotage Rate of injection Characteristics of spinal fluid Volume Pressure (cough/strain/Valsalva) Density

Factors Postulated to be Related to Spinal Anesthetic Block Height Patient characteristics Age Height Weight Gender Intra-abdominal pressure Anatomic configuration of spinal column Position

(七)麻醉中的管理 (intra-anesthesia management) ●BP↓and HR↓: 多发生于腰麻阻滞平面＞T4者. ▼ 表现:BP↓:多发生于注药后15-30min, 伴HR↓. 严重者躁动不安、面色苍白. 小A扩张→外阻↓. ▼ BP↓原因:交感N阻滞 小V扩张→血液淤积于周围 血管系→回心血量↓→C.O.↓. ▼HR↓原因: vagal tone dominance ▼ 处理: 补充血容量：加快输液200-300ml. 　　　 Ephedrine 5-10mg iv or 30mg im. 　　　 HR↓→Atropine.

●呼吸抑制(inhibition of respiration): ▼原因：麻醉平面过高→肋间肌麻痹. 复合药的影响（杜氟等). ▼表现：胸式呼吸微弱、腹式呼吸增强.潮气量↓ 咳嗽无力、不能发声、紫绀. ▼处理：有效吸O2、扶助呼吸. （“全脊麻”→呼吸停止、BP↓、心停→CPR） ●恶心、呕吐(nausea and vomit): ▼诱因：BP↓↓→脑供血↓↓→兴奋呕吐中枢. 　　　　 迷走N功能亢进→胃肠蠕动↑. 手术牵拉内脏. ▼处理：对症治疗

四、并发症 Complications 头痛 postoperative headache 尿潴留 urinary retention 原因：脑脊液外漏 处理：平卧至头痛消失，充分补充血容量，对症处理 尿潴留 urinary retention 原因：骶神经被阻滞 处理：导尿 较少见并发症 脑神经受累 假性脑膜炎 下肢瘫痪

特殊并发症 马尾神经综合征 原因：局麻药浓度过高 症状： 处理： 下肢感觉和运动功能长时间不恢复 神经系统检查发现鞍骶神经受累 大便失禁、尿道扩约肌麻痹 处理： 对症治疗

第二节 硬脊膜外阻滞麻醉 Section two Epidural anesthesia 一、概述(outline) 定义（definition） 将局麻药注入硬脊膜外间隙，阻滞脊神经根，使其支配的区域产生暂时性麻痹。

第二节 硬脊膜外阻滞 Section two Epidural anesthesia 一、概述(outline) 分类: 单次法:（少用） 延长麻醉作用时间. 连续法 提高硬膜外阻滞的可控性和安全性 高位：穿刺部位：C5-T6 中位：穿刺部位：T6-12 低位：穿刺部位：﹤T12 骶麻：穿刺部位：骶管

◆局麻药作用的部位(the site of action)： 二、硬膜外阻滞的作用机制及其生理影响 (The mechanism of action and physiologic responses) ◆局麻药作用的部位(the site of action)： ▲椎旁阻滞. ▲经根蛛网膜绒毛阻滞脊N根. ▲局麻药弥散过硬膜→蛛网膜下隙 →“延 迟”的脊麻.

◆局麻药在硬膜外间隙的扩散(pervasion) ●局麻药的容积和浓度 (volume and concentration): 容量→决定硬麻“量”的重要因素. 浓度→决定硬麻“质”的重要因素. ●注射速度(the speed of drug injection) : 注药过快→眩晕. ●体位、身高、年龄、妊娠 (position,height,age,pregnancy) ●其他：动脉硬化(arteriosclerosis) 脱水(dehydration) →需药量↓. 休克(shock) ◆硬膜外间隙压力(pressure)： 硬膜外间隙为负压(negative pressure):以颈部、胸部最高.

◆硬膜外阻滞的影响(systemic effects): ●CNS manifestations: ▼注药后一过性CSF pressure↑（过速→一过性 头晕）. ▼局麻药逾量或注入V丛→大量局麻药进入循 环 →惊厥(convulsion). ▼连续法→较长时间内累积性吸收→精神症状 (psychological symptom)、幻觉(illusion).

● Cardiovascular manifestations: ▲神经性因素： 阻力血管(resistance vessels) ★ 节段性交感神经阻滞 扩张 容量血管(capacitance vessels) ★ 平面＞T4→心交感N(cardiac sympathetic nerve)麻痹→HR↓ ▲药理性因素: ★局麻药吸收→平滑肌抑制 →抑制 β-R →C.O.↓ ★局麻药中Adr吸收→兴奋β-R→C.O.↑ ▲局部因素: 注速快→CSF pressure↑→短暂C.O.反射性↑

●Respiratory manifestations： ▲阻滞平面的影响(effects of level of blockade)： The level of sensory blockade＜T8→呼吸功能无明显影响. The level of sensory blockade ≥T2-4→膈N（diaphragm nerve) 抑制→肺活量(vital capacity)↓ ▲局麻药种类、浓度的影响 ▲年老、体弱、久病者→平面过高→通气储备不足 ▲其他因素:

●Visceral manifestations: 肠蠕动↑ ●Effects on muscular tension: 运动N阻滞不全,但仍有肌松作用. ▲反射性松弛：传入Nf被阻滞. ▲局麻药吸收后→选择性阻滞运动N末梢.

硬膜外镇痛作用产生的机制 局麻药：阻滞感觉神经纤维 阿片类药物：与阿片受体结合 阻断疼痛反应的恶性循环，减少创伤部位致疼物质释放；减轻神经内分泌反射；抑制疼痛反应中的中枢敏化机制和外周敏化机制

三、硬膜外阻滞的临床应用 (The clinical applications of epidural block) （ 一) 适应症与禁忌症 适应症 indications 颈部以下手术（以腹部以下为佳） 镇痛 （术后镇痛、产科镇痛、慢性疼痛） 禁忌症 contraindications 低血容量未纠正 穿刺部位感染 菌血症 低凝状态

(二) 常用局部麻醉药物 (Commonly used spinal anesthetic agents)

（三）注意事项 ◆局麻药中加用肾上腺素 减缓局麻药吸收速度、延长作用时间，局部轻度血管收缩，无明显全身反应. 常用1:20万(高血压病人禁用). ◆局麻药浓度选择 决定硬膜外阻滞范围的最主要因素 ——麻醉药容量 决定硬膜外阻滞深度和作用持续时间——麻醉药浓度 ◆局麻药的混合使用： 起效快+起效慢 潜伏期短 长效+短效 维持时间长 混合→

◆注药方式: 目的:排除误入蛛网膜下隙的可能； ● 注入增加量(incremental dose): ● 注射试验量(test dose):3-5ml. 目的:排除误入蛛网膜下隙的可能； ● 注入增加量(incremental dose): 注入试验量5-10min，如无腰麻征象 →可每隔5min注入 3-5ml，直至阻滞范围满足手术要求； ● 追加维持量(maintain dose):首次总量的1/2—1/3。

(四)硬膜外间隙穿刺术 病人体位 position 侧卧位 坐位

硬膜外间隙穿刺术 穿刺方法 穿刺位置 进入硬膜外腔的指征 直入法 midline approach 侧入法 paramidline approach 穿刺位置 根据手术的需要决定 进入硬膜外腔的指征 过黄韧带的突破感 出现负压 回抽无脑脊液 插管顺利

（五）连续硬膜外麻醉（CEA）

（六）硬膜外阻滞平面的调节 ▲ 穿刺部位(最重要) ▲ 导管位置和方向 ▲ 局麻药容量和注射速度 ▲ 体位 ▲ 穿刺部位(最重要) ▲ 导管位置和方向 ▲ 局麻药容量和注射速度 ▲ 体位 ▲ 病人情况：婴幼儿、老年人、妊娠后期.

（七）硬膜外阻滞失败的原因及处理 Failed Epidural Blocks 阻滞范围达不到手术要求 In other cases (traction on the peritoneum), intravenous supplementation with opioids or other agents may be necessary. 阻滞不全 Even if an adequate concentration and volume of an anesthetic were delivered into the epidural space, and sufficient time was allowed for the block to take effect, some epidural blocks are not successful. 完全无效 Misplaced injections of local anesthetic can occur in a number of situations.

（八）麻醉中的管理 BP↓and HR↓：多见于胸段硬膜外阻滞 内脏大小N麻痹→腹内血管扩张 →回心血量↓→BP↓ 迷走N功能相对亢进→HR↓ Inhibition of respiration 颈部、上胸段硬麻→肋间肌、膈肌不同程度麻痹→呼吸抑制 严重者呼吸停止)(高位硬麻宜采用小剂量、低浓度) Nausea and vomit 硬麻不能消除内脏牵拉痛，必要时行腹腔N丛阻滞

四、硬膜外阻滞并发症 血管内注射局麻药中毒 穿破硬脊膜 全脊麻 血压下降 呼吸抑制 脊神经根损伤 导管拔出困难或折断 硬膜外血肿

全脊麻 Total spinal anesthesia ◆概念(Concept)： 硬麻时→穿刺针或硬膜外导管误入蛛网膜下隙未能及时发现→超过腰麻数倍的局麻药误入蛛网膜下隙→全部脊N甚至颅N被阻滞→称全脊麻。 Total spinal anesthesia can occur following attempted epidural/caudal anesthesia if there is inadvertent intrathecal injection. Onset is usually rapid because the amount of anesthetic required for epidural and caudal anesthesia is 5–10 times that required for spinal anesthesia. Careful aspiration, use of a test dose, and incremental injection techniques during epidural and caudal anesthesia can help avoid this complication.

◆临床表现(manifestation): ★全部脊N支配区域无痛觉(no sense of pain) ★严重低血压休克(severe hypotention) ★意识丧失(unconsciousness) ★呼吸停止(respiratory arrest) → 心跳停止(cardiac arrest)（处理不及时)

◆处理原则(principle of treatment) 维持循环、呼吸功能 Treatment consists of supporting the airway, maintaining an adequate ventilation, and supporting the circulation. 人工通气: When respiratory insufficiency becomes evident, supplemental oxygen is mandatory . Assisted ventilation, intubation, and mechanical ventilation may be necessary. 加速输液: Hypotention can be treated with rapid administration of intravenous fluid. 升压药等对症处理: Aggressive use of vasopressors. Bradycardia should be treated with atropine.

异常广泛阻滞: The exception that the onset may be delayed for 15-30minutes. The effects generally last from one to several hours. ●注入常规剂量局麻药后→异常广泛的脊N阻滞现象.（并非全脊麻） ●范围虽广，仍为节段性，骶N支配区域、甚至腰部N 功能仍正常 ●广泛阻滞缓慢发生→注入药量后20-30min ●胸闷、呼吸困难、说话无力、烦躁不安→通气严重不 足 →呼吸停止、BP↓↓

穿破硬膜: 穿刺置管损伤血管或导管进入并留滞于血管 空气栓塞： 穿破胸膜：气胸、纵隔气肿 ◆预防: 严格操作规程 ◆穿破后处理: ◆原因: ★操作因素: ★病人因素: ◆预防: 严格操作规程 ◆穿破后处理: 穿刺置管损伤血管或导管进入并留滞于血管 导管误入血管→注麻药后立即出现全身中毒反应而麻醉作用缺如 . 处理：退管1-2cm or换间隙重穿置管 空气栓塞： 注气试验时→空气进入循环→量多时致死 穿破胸膜：气胸、纵隔气肿

硬膜外血肿(Epidural hematoma) ◆ Needle or catheter trauma to epidural veins often Causes minor bleeding , although this is usually benign and self- limiting.A clinical significant epidural hematoma can occur following epidural anesthesia, especially in the presence of abnormal coagulation or bleeding disorder. 发生率0.01‰,虽罕见，但在麻醉并发截瘫原因中占首位. ◆ The need for rapid diagnosis and intervention is paramount, if permanent neurologic sequelae is to be avoided.

◆ Symptoms include sharp back and leg pain with a progression to numbness and motor weakness and/or sphincter dysfunction. ◆ When hematoma is suspected, neurologic image(MRI,CT) must be obtained immediately.Most cases of good neurologic recovery have occurred in patients who have undergone surgical decompression within 8-12 hours. 预防： ●导管质地柔软，穿刺置管要轻巧. ●对有凝血障碍(coagulopathy)或血小板功能障碍（platelet dysfunction)正在抗凝(anticoagulation)的病人避免做硬麻. ●凡疑硬膜外血肿→立即造影→24h内手术减压.

脊神经根或脊髓损伤: ◆神经根损伤(neural root trauma): ◆脊髓损伤(spinal cord trauma) ： 脊N根损伤主要是后根→根痛（受伤N根的分布区疼痛).咳嗽、 喷嚏、用力憋气时疼痛or 麻木加重(脑脊液冲击征),损伤后3天 内最剧,遗留片状麻木区数月以上. ◆脊髓损伤(spinal cord trauma) ： 导管插入脊髓or局麻药注入脊髓→横贯性损害(立即感剧痛,一 过性意识障碍→完全性松驰性截瘫)→终生残废. 脊髓穿刺伤→继发性水肿(截瘫). 治疗：脱水、激素(及早使用).

神经根损伤 脊髓损伤 ●感觉障碍为主,典型根痛 ●触电或痛感 感觉、运动障碍 很少运动障碍 感觉障碍与穿刺点不在 剧痛，一过性意识障碍 ●感觉障碍为主,典型根痛 很少运动障碍 感觉、运动障碍 ●感觉缺乏仅限于1～2根脊N支配区,与穿刺点棘突平面一致 感觉障碍与穿刺点不在 同一平面，比穿刺点低

五、小儿硬膜外阻滞： 出生时脊髓终止于L3水平，1岁时达L1-2水平。 药物剂量： 新生儿：0.75% Lidocaine 2～3ml 早产新生儿、一般情况不佳→适当降低浓度、剂量. 婴儿：1% 小儿：1.5% 剂量于0.7-1.0ml/kg （7-10mg/kg） (Lidocaine) 儿童：2%

六、骶管阻滞(Caudal anesthesia) 骶管穿刺术: 骶骨孔与左、右髂棘的等边三角关系(定位参 考). 穿刺针端不超过两髂棘联线—不致于穿破硬膜 骶管容积： 25ml±（成人），麻药必须将骶管充满才能使 所有 骶N阻滞 ▼腰骶部硬外间隙解剖结构特殊→麻药不易由骶侧向腰侧 扩散→麻醉范围主要集中于肛门、会阴、臀部→对生理 功能影响轻微. ▼骶骨孔解剖变异多→成功率相对低（75—80%) ▼ 骶管内血管窦粗大→易出血、局麻药中毒. （现已用L3-4↓代替骶麻）

第三节 蛛网膜下隙与硬脊膜外联合阻滞麻醉  Section three Combination of spinal and epidural anesthesia 蛛网膜下腔与硬膜外腔联合麻醉 蛛网膜下腔阻滞：镇痛、运动神经阻滞 硬膜外腔阻滞：长时间手术、神经分离阻滞 穿刺方法 两点法 先行硬膜外腔穿刺术、再行蛛网膜下腔穿刺 一点法 利用联合穿刺针，在同一个位置分别进行硬膜外腔穿刺和蛛网膜下腔穿刺

Possible Clinical Advantages of Using Combined Spinal-Epidural Anesthesia Initial epidural needle placement allows the spinal needle to be guided near the dura, minimizing the number of times the spinal needle tip impacts bone and potentially becomes dulled. Lower local anesthetic blood levels are possible when an initial spinal anesthetic is used for operation, and the epidural catheter is used for analgesia. More rapid onset of spinal block allows the operative procedure to begin earlier, while the epidural catheter allows effective analgesia to be provided. During labor, an opioid may be injected via a small spinal needle and then epidural analgesia added if needed. Lower initial mass of drug may be used during spinal anesthesia, thereby minimizing the physiologic perturbations, while the epidural catheter is available to provide a higher level if needed.

Question What are the major differences between subarachnoid block and extradural block? What are the methods for identifying the epidural space? What are the absolute contraindications to subarachnoid block and extradural block?

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