05椎管内麻醉.doc

Intrathecal Anesthesia IntroductionIntrathecal anesthesia is accomplished by injecting a local anesthetic into intrathecal space , which blocks conduction of spinal nerve roots , producing regional anesthesia . Intrathecal block is divided into Subarachnoid block : Local anesthetic is injected into subarachnoid space. Epidural block : Local anesthetic is injected into the epidural space . Intrathecal blocks result in sympathetic block , sensory analgesia , and motor block 。AnatomyVertebral column and vertebral canal Vertebral column Vertebral column consists of 7 cervical ( C ) , 12 thoracic (T ) , 5 lumbar (L ) , 5 sacral ( S ) are fused as the sacrum , and 4 small coccygeal vertebra ( Co ) that form the coccyx . Each vertebra has a large vertebral foramen , the vertebral foramen collectively form a bony tube , the vertebral canal . This canal encloses and protects part of the central nervious system , the spinal cord . Ligamentum of vertebral columnSurrounding the vertebral canal are mainly three ligamentum :Supraspinous ligamentInterspinous ligamentLigamentum flavum ( the yollow ligament ) , Vertebral canal General remarksThe vertebral canal is formed by successive vertebral foramina ,it enclosed and protects the spinal cord .Spinal cord Spinal cord is protected by the vertebrae , their associated ligaments , muscles , the spinal meninges , and CSF . The spinal meninges and CSF Surrounding the spinal cord in the bony vertebral column are three membranes ( from within to the outside ) : the pia mater , arachnoid mater , and dura mater . . Between the pia mater and arachnoid mater is the subarachnoid space , in this space are the CSF , spinal nerve roots . The third membrane ( outermost membrane ) in the spinal canal is the dura mater . Surrounding the dura mater is the epidural space , the epidural space extends from the base of the skull to the sacral hiatus . The epidural space is between the dura mater and the ligamentum flavum ( the yollow ligament ) . It contains fat , loose connective tissue , and venous plexus .Physiologic Effects of Intrathecal Anesthesia1 , Respiratory system Low spinal block or low epidural block has no effect on the respiratory system . Motor blockade extending to the roots of the phrenic nerves ( C3-5 ) causes apnea .2, Cardiovascular system Decrease in blood pressure Bradycardia may occur 3. Gastrointestinal manifestationsNausea , retching or vomiting may occur in the awake patient Spinal anesthesiaSAB is a type of regional anesthesia , which is achieved by injecting a local anesthetic into the lumbar subarachnoid space.Useful local anesthetic for SABThe specific gravity of CSF is 1.003-1.009 at 37 . hyperbaric solution of local anesthetic , and it is heavier than CSF .A hypobaric solution is lighter than CSF , it can be made by the addition of sterile water .An isobaric solution tends to remain at the level of injection , anesthetic agents are mixed with CSF .Local anestheticsLidocaineTetracaineBupivacaine Factors influencing level of block in hyperbaric solution. Patients position Drug dosage & volume Speed of injection Needle bevel direction Puncture siteComplications of spinal anesthesia Hypotension Bradycardia Nausea and vomiting Headache ( post dural puncture headache , PDPH ) Urinary retentionIndications and contraindicationsIndications SAB is most suited to surgery below the umbilicus , such as , surgery of perineum , lower limbs and lower abdomen .Contraindications Infection at the site of puncture Bleeding diathesis or coagulopathy . Severe hypovolemia . evere cardiovascular diseases . Severe spinal deformity . Preexisting neurologic diseases. Intracranial high pressure . Epidural AnesthesiaIntroductionEpidural anesthesia is achieved by injecting a local anesthetic into the epidural space , which blocks the spinal nerve roots , producing regional anesthesia. Particularly , an epidural anesthesia can be performed at the lumbar , thoracic , or cervical and sacral level .Technique of epidural puncture Approach of epidural puncture : Patients position How to recognize when the tip of the needle has entered the epidural space ？ loss of resistance hanging drop Epidural anesthetic agents Lidocaine Bupivacaine RopivacaineAdministration of local anestheticThe quantity of local anesthetic need for epidural anesthesia is relatively large compared with spinal anesthesia . Significant toxicity can occur if this amount is injected intrathecally or intravascularly A test dose Aim : to detect subarachnoid injection , to detect intravascular injection . Incremental dosingIncremental dosing is a very effective method of avoiding serious complication . After 5min of test dose given , there is no adverse reaction then incremental dosing is injected into epidural space .Factors affecting level of anesthesia The volume Age Pregnancy Height : Selection of the puncture point . ComplicationsIntraoperative complication Dural tap Total spinal anesthesia. Toxic reaction Nausea or vomiting Respiratory depression Postoperative complication Headache Neurologic injury Epidural hematoma Epidural abscess Anterior spinal artery syndrom .Indications and contraindicationsIndicationsThe indications for epidural anesthesia are widespread , it includes : Operation of chest wall . Major abdominal operation . Gynecology and obstetrics. Lower extremity surgery Urologic surgery .Contraindications Patient refusal . Local infection at the site of injection . Severe hemorrhage or shock . Severe hypovolemia . Coagulopathy or anticoagulant therapy . Severe cardiovascular diseases Preexisting neurologic diseases Septicemia .How to differ between a spinal anesthesia and epidural anesthesia .Differences between spinal and epidural anesthesia SAB EpiduralA site of puncture L2 C,T,L,SA site of injection of subarachnoid space epidural space Dose small Large toxicity toxicity after intravascular injectionPattern of block Transection Upper and lower levelMethod of injection Single Single shot technique Continuous catheter technique Key words Anesthesia 麻醉;感觉缺失 Sympathetic block 交感神经阻滞 Analgesia无痛觉Subarachnoid space 蛛网膜下腔 dural 硬脊膜的 Epidural space 硬膜外腔Supraspinous , 棘上的interspinous, 椎间的ligament 韧带ligamentum flavum( yellow ligament ) 黄韧带Bradycardia 心搏徐缓 Blood pressure.血压 Nausea 恶心;作呕vomite 呕吐 retch 干呕Spinal anesthesia 蛛网膜下腔麻醉 epidural anesthesia硬膜外腔麻醉baricity 比重 hyperbaric 高比重的 hypobaric 低比重的 Isobaric 表示等压的CSF cerebrospinal fluid 脑脊液Epinephrine 肾上腺素 procaine 普鲁卡因 tetracaine 丁卡因 bupivacaine 布比卡因Vasoconstrictor 血管收缩剂 phenylephrine苯肾上腺素(一种血管收缩剂)Sympathectomy 交感神经切除术( 阻滞)Saddle block 鞍区阻滞麻醉(麻醉术之一种)Unilateral block 单边阻滞Ephedri