麻醉学第五节 椎管内麻醉

1、 第五节椎管内麻醉1 椎管内麻醉系将局麻药注入椎管内的不同腔隙，使脊神经所支配的相应区域产生麻醉作用，包括蛛网膜下腔阻滞麻醉和硬膜外阻滞麻醉两种方法，后者还包括骶管阻滞。局麻药注入蛛网膜下腔，主要作用于脊神经根所引起的阻滞称为蛛网膜下腔阻滞，通称为脊麻；局麻药在硬膜外间隙作用于脊神经， 使相应节段的感觉和交感神经完全被阻滞，运动神经纤维部分地丧失功能，这种麻醉方法称为硬膜外阻滞。2硬膜外阻滞 椎管内麻醉蛛网膜下腔阻滞 腰硬联合3History of spinal anesthesia 1885 J.L. Corning (New York Neurologist):? epidural;? s

2、pinal; cocaine for pain relief 1891 Quincke (Germany): lumbar puncture 1899 August Bier (Germany): first cocaine spinal anesthesia in six patients 1899 Matas (New Orleans), Tuff ier (France), Tait and Caglieri (San Francisco): cocaine spinal anesthesia 1905 H. Braun (Germany): procaine spinal anesth

3、esia 1907 Barker (United Kingdom): hyperbaric procaine (glucose); hypobaric procaine (alcohol) 1930 Jones (United Kingdom): dibucaine spinal anesthesia 1935 Sise (USA): tetracaine spinal anesthesia 1940 Lemmon (USA): continuous spinal anesthesia 1945 Tuohy (USA): continuous spinal anesthesia 1945 Pr

4、ickett (USA): report on neurologic safety of intrathecal epinephrine to prolong spinal anesthesia 1954 Wooly and Roe (United Kingdom): report of paraplegia in association with spinal anesthesia 1954 Dripps and Vandam (USA): study demonstrating absence of neurologic sequelae 1965 Re-emergence of use

5、of spinal anesthesia 4椎管内解剖5椎管内解剖6椎管内解剖7 Composition of cerebrospinal fluid Specific gravity 1.006 (1.003-1.009) (at 37C) Volume 120150 ml (2535 ml spinal space) CSF pressure (lumbar) 6080 mm H20 (in horizontal position) pH 7.32 (7.277.37) (cisternal pH follows blood; lumbar pH lags behind) PC02 48

6、mm Hg HC03 23 mEq/L Sodium 133145 mEq/L Calcium 23 mEq/L Phosphorus 1.6 mg/dl Magnesium 2.02.5 mEq/L Chloride 1520 mEq/L Proteins (lumbar) 2338 mg/dl ( permeability to protein in lumbar area) 8 椎管内解剖9脊髓及硬膜囊的位置10三蛛网膜下腔阻滞11（一）分类给药方式 单次 连续麻醉平面 高 T4-T10 中 低 局麻药的比重 重 轻 等比重12131415161718腰麻穿刺术穿刺方法 穿刺点用0.5%

7、1%普鲁卡因作皮内、皮下和棘间韧带逐层浸润。1. 直入法 用左手拇、示两指固定穿刺点皮肤。将穿刺针在棘突间隙中点，与病人背部垂，针尖稍向头侧作缓慢刺入，并仔细体会针尖处的阻力变化。当针穿过黄韧带时，有阻力突然消失“落空”感觉，继续推进常有第二个“落空”感觉，提示已穿破硬膜与蛛网膜而进入蛛网膜下腔。如果进针较快，常将黄韧带和硬膜一并刺穿，则往往只有一次“落空”感觉。192. 旁入法 于棘突间隙中点旁开1.5cm处作局部浸润。穿刺针与皮肤成75度对准棘突间孔刺入，经黄韧带及硬脊膜而达蛛网膜下腔。本法可避开棘上及棘间韧带，特别适用于韧带钙化的老年病人或脊椎畸形或棘突间隙不清楚的肥胖病人。针尖进入蛛网

8、膜下腔后，拔出针芯即有脑脊液流出20 Drugs for spinal anesthesia Dose (mg) Duration (min)a Drug and concentration To L4 To T10 To T4 Plain With 0.2 mg epinephrine Procaine (5%) 5075 100150 150200 4055 6075 Lidocaine (5%) 2550 5075 75100 6070 6070 Tetracaine (0.5%) 46 610 1216 6090 120180 Bupivacaine (0.75%)b 48 812 1

9、420 90110 90110 a For a given local anesthetic in spinal anesthesia the larger mg dose, the longer the duration of surgical anesthesia (e.g., a 16 mg dose of tetracaine will have a duration of two to three times longer than a 4 mg dose, either plain or with epinephrine. b Bupivacaine 0.5% is availab

10、le as an isobaric solution that is ideal for surgery below the level of T10, such as hip surgery. Motor block with this solution is profound and long lasting in the legs. Doses are 10 to 15 mg for the L4 level and 15 to 20 mg for the T10 level. A heavy solution of bupivacaine 0.5% is also available

11、and is suitable for abdominal surgery. Doses and effects are similar to those obtained with the bupivacaine 0.75% solution. 21- Drug selection for hyperbaric spinal anesthesiaDose (mg) * Duration (min)Local Anesthetic MixtureTo T10To T4PlainEpinephrine, 0.2 mgLidocaine (5% in 7.5% dextrose)506075100

12、6075100Tetracaine (0.5% in 5% dextrose)6810167090100150Bupivacaine (0.75% in 8.5% dextrose)810122090120100150Ropivacaine (0.5% in dextrose)1218182580110Levobupivacaine8101220901201001502223以重比重药为例，因体位改变，麻醉平面的而改变2425262728麻醉平面29麻醉平面30影响阻滞平面的因素1局麻药的剂量及比重，病人的体位。病人体位和局麻药的比重是调节麻醉平面的两主要因素，局麻药注入脑脊液中后，重比重液向

13、低处移动，轻比重液向高处移动，等比重液即停留在注药点附近，所以坐位注药时，轻比重液易向头侧扩散，使阻滞平面过高；。2穿刺部位：脊椎的四个生理弯曲在仰卧位时，腰3最高，胸6最低（图42-6），如果经腰23间隙穿刺注药，病人转为仰卧后，药物将沿着脊柱的坡度向胸段移动，使麻醉平面偏高；如果在腰34或腰45间隙穿刺，病人仰卧后，大部药液向骶段方向移动，骶部及下肢麻醉较好，麻醉平面偏低，因此于腹部手术时，穿刺点宜选用腰23间隙；于下肢或会阴肛门手术时，穿刺点不宜超过腰34间隙3注药的速度：愈快，麻醉范围愈广；。一般以每5秒注入1毫升药物为适宜。4穿刺针斜口方向：斜口方向向头侧，麻醉平面易升高；反之，麻醉

14、平面不易过多上升。31（一）血压下降和心率缓慢蛛网膜下腔阻滞平面超过胸4后，常出现血压下降，主要是由于交感神经节前神经纤维被阻滞，使小动脉扩张，周围阻力下降，加之血液淤积于周围血管系，静脉回心血量减少，心排血量下降而造成。心率缓慢是由于交感神经部分被阻滞，迷走神经呈相对亢进所致。处理上应首先考虑补充血容量，如果无效可给予血管活性药物（麻黄碱、间羟胺等），直到血压回升为止。对心率缓慢者可考虑静脉注射阿托品0.25mg0.3mg以降低迷走神经张力。（二）呼吸抑制因胸段脊神经阻滞引起肋间肌麻痹，可出现呼吸抑制表现为胸式呼吸微弱，腹式呼吸增强，应迅速有效吸氧。如果发生全脊麻而引起呼吸停止，血压骤降或心

15、搏骤停，应立即施行气管内插管人工呼吸、维持循环等措施进行抢救。（三）恶心呕吐诱因有三：血压骤降，脑供血骤减，兴奋呕吐中枢；迷走神经功能亢进，胃肠蠕动增加；手术牵引内脏。术中并发症321脊麻后头痛是常见的并发症，由于脑脊液通过硬膜穿刺孔不断丢失，使脑脊液压力降低所致，典型的症状为直立位头痛，而平卧后则好转。疼痛多为枕部、顶部，偶尔也伴有耳鸣、畏光。性别、年龄及穿刺针的直径影响头痛的发生率（表43-1），女性的发生率高于男性，发生率与年龄成反比，与穿刺针的直径成正比。穿刺针斜面的方向与脊膜纤维走向平行，对脊膜损伤最少，所以脑脊液的漏出最低，头痛的发生率也低。33 Relationships amo

16、ng variables and postdural puncture headacheFactors that May Increase the Incidence ofPostduralPuncture HeadacheAge:Younger more frequentGender:Females malesNeedle size:Larger smallerNeedle bevel:Less when needle bevel placed in the long axis of neuraxisPregnancy:More when pregnantDural punctures (n

17、o.):More with multiple puncturesFactors Not Increasing the Incidence of Postdural Puncture HeadacheContinuous spinalsTiming of ambulation34尿潴留神经系统并发症：脑神经受累假性脑脊膜炎（化学性脑脊膜炎)粘连性蛛网膜炎马尾综合征表现为脊麻后下肢感觉及运动功能长时间不恢复，神经系统检查发现鞍骶神经受累、大便失禁及尿道括约肌麻痹，恢复异常缓慢。脊髓缺血和脊髓炎35适应证1. 下腹部手术 如：阑尾切除术、疝修补术。2. 肛门及会阴部手术 如：痔切除术、肛瘘切除术、直

18、肠息肉摘除术、前庭大腺囊肿摘除术、阴茎及睾丸切除术等。3. 盆腔手术包括一些妇产科及泌尿外科手术，如：子宫及附件切除术、膀胱手术、下尿道手术及开放性前列腺切除术等。4. 下肢手术包括下肢骨、血管、截肢及皮肤移植手术，止痛效果可比硬膜外阻滞更完全，且可避免止血带不适。361. 精神病、严重神经官能症以及小儿2. 严重低血容量的病人3. 凝血功能异常的病人。4. 穿刺部位有感染的病人 穿刺部位有炎症或感染者，脊麻有可能将致病菌带入蛛网膜下腔5. 中枢神经系统疾病，特别是脊髓或脊神经根病变者，麻醉后有可能后遗长期麻痹，疑有颅内高压病人也应列为禁忌。6. 脊椎外伤或有严重腰背痛病史者。37四，硬膜外阻

19、滞38 Key levels of dermatomal blockade Cutaneous landmark Segmental level Significance Little finger C8 All cardioaccelerator fibers (T1T4) blocked Inner aspect of arm and forearm T1 and T2 Some degree of cardioaccelerator blockade Apex of axilla T3 Easily remembered landmark Nipple line (midway ster

20、nal notch and xiphisternum) T4T5 Possibility of cardioaccelerator blockade Tip of xiphoid T7 Splanchnics (T5L1) may become blocked Umbilicus T10 Sympathetic blockade limited to lower limbs Inguinal ligament T12 Outer side of foot S1 No lumbar sympathetic blockade Most difficult nerve root to block 3

21、94041424344穿刺技术穿刺体位及穿刺部位穿刺体位有侧卧位及坐位两种，临床上主要采用侧卧位，具体要求与蛛网膜阻滞法相同。穿刺点应根据手术部位选定，一般取支配手术范围中央的相应棘突间隙。穿刺方法硬膜外间隙穿刺术有直入法和旁入法两种。颈椎、胸椎上段及腰椎的棘突相互平行，多主张用直入法；胸椎的中下段棘突呈叠瓦状，间隙狭窄，穿刺困难时可用旁入法。老年人棘上韧带钙化、脊柱弯曲受限制者，一般宜用旁入法。直入法、旁入法的穿刺手法同蛛网膜下腔阻滞的穿刺手法，针尖所径的组织层次也与脊麻时一样，如穿透黄韧带有阻力骤失感，即提示已进入硬膜外间隙。4546穿刺针到达黄韧带后，根据阻力的突然消失、负压的出现以及无

22、脑脊液流出等现象，即可判断穿刺针已进入硬膜外间隙。临床上一般穿刺到黄韧带时，阻力增大有韧感，此时可将针芯取下，用一湿润的空注射器与穿刺针衔接，当推动注射器芯时即感到有弹回的阻力感 474849 Possible factors in neurologic sequelae in patients receiving epidural block1. Direct trauma to spinal nerve roots, spinal cord 2. Compression of spinal cord or nerve roots Epidural hematoma Epidural abs

23、cess Postpartum paresis owing to cephalopelvic disproportion (may also compress spinal cord feeder vessels) 3. Neurotoxicity Low pH, high concentration of antioxidants (e.g., bisulfite) (see Chapter 4 and Chapter 30) Neurotoxic additives (e.g., ethanol, benzyl alcohol, chlorocresol, methylparaben)a

24、Injection of wrong drug (i.e., not a local anesthetic) 4. Ischemia 5. Anterior spinal artery spasm or thrombosis Trauma by needle Spasm ? by epinephrine or other factors Thrombosis owing to very low blood pressure (e.g., only in those with vascular disease) ? Combination of hypotension and injection of large volume of local anesthetic raising CSF pressure (see Chapter 30) 6. Ischernia within spinal cord ? Neurotoxic effects by way of reduced perineurial blood