脊柱手术的麻醉剖析

脊柱手术的麻醉椎间盘问题脊椎滑脱需要手术治疗的脊柱问题椎管狭窄脊柱侧凸驼背脊髓肿瘤需要手术治疗的脊柱问题硬膜外血肿和脓肿,外伤……手术操作椎板切开术椎板切除术椎间盘摘除术手术操作融合和固定内固定术术前评估气道评估:张口度是否有困难插管史头颈活动度颈椎的稳定性与外科医生沟通是必须的麻醉注意事项呼吸系统病史:关注肺功能是否有损害体检:肺部感染的体征；严重的脊柱畸形胸部X线肺功能检查:脊柱侧凸血气分析心血管系统病史:高血压,糖尿病,充血性心力衰竭,冠心病体检:充血性心力衰竭体征心电图应激试验/心超实验室检查（推荐）基本检查可选检查气道颈椎侧位片CT扫描肺部胸片肺功能检查血气分析(支气管扩张试验)肺功能检查(FEV1,FVC)肺弥散功能检查心血管心电图多巴酚丁胺应激Echo超声心动图潘生丁/铊扫描图血液检查CBC,electrolytes,Cr肝功能检查BUN,PT/PTTAlbumin,calcium(肿瘤疾病)神经系统评估整个神经系统评估都应记录在案1.颈椎手术的病人,麻醉科医生有责任在插管和放置体位时避免进一步的损伤2.肌肉萎缩增加术后反流误吸的风险3.脊髓损伤的程度和时间与围术期出现心血管和呼吸系统功能紊乱密切相关（小于3周,脊髓休克症状仍可出现；3周后可能出现自主神经反射失调麻醉技巧诱导:麻醉诱导的选择:i.v.orinhalation?病人的医疗状况气道颈椎稳定性肌松药的选择:SuccinylcholineorNDNMBs?病人的医疗状况气道返流误吸术中监测麻醉技巧插管Awakeorasleep?清醒气管插管:返流误吸可能插管后行神经评估:不稳定颈椎颈部稳定装置:halotractionDirectorfiber-opticlaryngoscopy?直接喉镜插管:包括可视喉镜等纤支镜:畸形:上胸段和颈部颈托固定的病人解剖异常:小下颌畸形，张口度小上胸段和颈部手术的插管流程麻醉维持维持稳定的麻醉深度避免因麻醉深度的突然改变而引起的血压波动Commonpractice:0.5MACIsoorsevocontinuousinfusionofpropofolcontinuousremifentanylorbolusopioids麻醉苏醒拔管:完全清醒对指令有反应气道自我保护恢复麻醉技巧脊柱手术中的特殊挑战体位术中监测脊髓损伤术后失明或视力低下(POVL)体位PronepositionforC-spineprocedure俯卧位引起的麻醉中的问题气道:气管导管扭曲或移位长时间手术导致上呼吸道水肿血管:上肢动脉和静脉阻塞股静脉扭曲，DVP腹腔内压:硬膜外静脉压出血神经:臂丛神经牵拉和受压尺神经受压:尺嘴鹰骨受压腓总神经受压:压迫腓骨小头股外侧皮神经损伤:压迫髂嵴头和颈:头颈屈曲或伸展过度眼部受压:视网膜损伤眼睛缺乏润滑和覆盖:角膜靠枕可能引起框上神经受压和损伤.颈部过度扭曲:臂丛神经损伤颈动脉受压坐位颈部椎板切除术病人手术应检查颈部活动情况应用坐位行颈部椎板切除术的比例逐渐增多坐位手术的缺点为静脉气栓的危险性增加坐位手术病人应防止神经、皮肤损伤注意颈部过度前屈可阻塞气道给病人以适当液体补充，且逐渐改变体位有助于防止低血压。并发症静脉气栓是脊柱手术严重并发症之一表现为无法解释的低血压、呼气末氮气水平升高早期诊断和处理可提高存活率脊髓功能监测截瘫是脊柱手术最严重的并发症常用唤醒试验和神经生理功能监测术中监测唤醒试验Wake-uptest体感诱发电位SSEPs动作诱发电位MEPsLighteninganesthesiaatanappropriatepointduringtheprocedureandobservingthepatient’sabilitytomovetocommand.Itevaluatesthegrossfunctionalintegrityofthemotorpathway.Itwasfirstdescribedin1973.麻醉要求:简单和快速确切和快速拮抗药温柔唤醒试验过程中无痛Norecall唤醒试验Wake-uptest麻醉基数:吸入麻醉药咪唑安定丙泊酚瑞芬太尼缺点:需要患者配合插拔气管导管实践延长手术时间不能评估感觉通路唤醒试验Wake-uptestSSEPs1.Themostcommonneurophysiologicalmethodformonitoringtheintra-operativespinalfunctionalintegrity2.ThestimulusappliedtotheperipheralN(tibialorulnar)3.Therecordingelectrodesplaced:cervicalregion,scalp,orepiduralspaceduringsurgery4.Baselinedataobtainedafterskinincision5.Responsesarerecordedintermittentlyduringsurgery6.Areductionintheamplitudeby50%andanincreaseinthelatencyby10%areconsideredsignificant.TypicaltracingandL-101.SSEPsprovidesanindirectwayofmonitoringadjacentmotorpathwaysbecausemoreacuteimpairmentaffectsfunctionofmanyadjacentpathways,notjusttheposteriorcolumn.However,thiscannotbeguaranteed.2.Thebloodsupplyofthecorticospinalmotortractsdiffersfromthatofthedorsomedialsensorytracts.ItispossibletohavenormalSSEPsrecordingsthroughoutsurgery,buttohaveaparaplegicpatientpostoperatively.SatisfactorymonitoringofearlycorticalSSEPsispossiblewith0.5–1.0MACisoflurane,desfluraneandsevoflurane.NitrousoxidepotentiatesthedepressanteffectofvolatileanestheticsIntravenousanestheticsgenerallyaffectSSEPslessthaninhaledanestheticsEtomidateandketamineincreasescorticalSSEPamplitudeClinicallyunimportantchangesinSSEPlatencyandamplitudeaftertheadministrationofopioids麻醉药和SSEPsSSEPs监测意义EliminatingN2OfromthebackgroundanesthetichasbeenshowntoimprovecorticalamplitudesufficientlytomakemonitoringmorereliableSSEPlatencywilltake5–8mintostabilizeafterthestepchangesinvolatileanestheticconcentrationAddingetomidate,propofoloropioidsispreferabletobeginningN2OorincreasingvolatileanestheticconcentrationswhenanestheticdepthisinadequateIfavolatileanestheticisneverthelessneededrapidly,sevofluranepermitsfasterSSEPrecoveryaftertheacuteneedforvolatileanesthetichasbeenresolvedItiscriticaltoavoidsuddenchangesinvolatileanestheticdepthorbolusadministrationofintravenousanestheticsduringsurgicalmanipulationsthatcouldjeopardizetheintegrityoftheneuralpathwaysbeingmonitoredMEPsMotorcortexstimulatedbyelectricalormagneticmeansMyogenicresponsesNeurogenicresponses:peripheralNorspinalcord麻醉药和MEPsInhalationalanestheticssuppressmyogenicMEPsinadose-dependentmannerPairedpulsesoratrainofpulsescannotovercomethesuppressiveeffectsShouldbeavoided,orlimitedtoaverylowconcentrationduringthemonitoringofmyogenicMEPsN2Oappearstobelesssuppressivethanotherinhaledagents.Moderatedosesofupto50%N20havebeenusedsuccessfullytosupplementotheragentsduringmyogenicMEPmonitoring.Fentanyl,etomidate,andketaminehavelittleornoeffectonmyogenicMEPandarecompatiblewithintra-operativerecording.Benzodiazepines,barbiturates,andpropofolalsoproducemarkeddepressionofmyogenicMEP.However,successfulrecordingshavebeenobtainedduringpropofolanesthesiabycontrollingserumpropofolconcentrationsandincreasingstimulirates.MyogenicMEPsareaffectedbythelevelofneuromuscularblockadeByadjustingacontinuousinfusionofmusclerelaxanttomaintainoneortwotwitchesinatrainoffour,reliableMEPresponseshavebeenrecordedMotorstimulationcanelicitmovement,andthiscaninterferewithsurgeryintheabsenceofneuromuscularblockadePhysiologicfactorssuchastemperature,systemicbloodpressure,PaO2,andPaCO2canalterSEPs/MEPsandmustbecontrolledduringintra-operativerecordings麻醉药和MEPs脊髓损伤1.手术和麻醉引起的神经损伤并不局限于手术部位2.不良的手术体位可能导致截瘫和四肢瘫痪3.神经损伤最多见还是在手术部位危险因素:•手术种类和手术时间的长短•脊髓血供（灌注压）•潜在的脊柱病理改变•术中神经组织的受压程度脊髓