A38-year-oldmandevelopedhypoxemiafollowinganelectiverightheartcatheterization.Hewasbeingevaluatedforpulmonaryhypertension.Thehypoxemiaimprovedwithoxygensupplementation,andthepatientwasadmittedtothehospitalforfurtherworkupandmanagement.Overnight,followinghospitaladmission,thepatientbecamestuporous.Oxygensaturationwas98%on3Lperminutenasalcannula;arterialbloodgas(ABG)revealedsignificantrespiratoryacidosiswithpH7.19andCO2.mmHg.Thepatientwasemergentlyintubatedandmechanicallyventilated.Chestx-rayshowedverylowlungvolumes.Thepatientimprovedandwasextubated2dayslater.Hispulmonaryfunctioningtest(PFT)valuesfollowingextubationwerecmH2Onegativeinspiratoryforce(NIF)sittingup,cmH2ONIFlyingflat,1.10Lforcedvitalcapacity(FVC)sittingup,and0.95LFVClyingflat.Theetiologytobothhispulmonaryvasculardiseaseandrespiratoryfailureremainedunclear,andatthattimeweevaluatedthepatientforneuromuscularcausesofrespiratoryfailure.
38岁男性行肺动脉高压评估，在选择性右心导管检查后出现低氧血症。吸氧后低氧血症改善，医院进一步检查和治疗。住院后患者夜间出现意识不清。鼻导管吸氧3L/分，血氧饱和度为98%；动脉血气分析（ABG）显示明显的呼吸性酸中*，PH7.19，二氧化碳分压mmHg。紧急给予患者气管插管和机械通气。胸部X线片显示肺容积非常低。2天后患者症状改善拔除气管插管。拔管后肺功能检查（PFT）值坐位负力吸气（NIF）为-50cm水柱，平卧位时NIF为-45cm水柱，坐位时用力肺活量（FVC）1.10升，平卧时0.95升。患者肺血管疾病和呼吸衰竭原因均不明，当时我们对患者呼吸衰竭的神经肌肉方面的原因进行了评估。
Thepatientclaimedtobeastellarathleteinhisyoungerdays,buthisfunctionalstatusslowlydeclinedovertime.Thepatientfirstnoticedweaknessatage27years,whenherealizedhecouldnolongerjumpashighasbefore.Hethenbeganhavingtroubleclimbingstairsduetobothhipweaknessandshortnessofbreath.Atage30,hestartedhavingdifficultywalkingandwouldoccasionallyfall.Atage34,henoticedshortnessofbreathwhenlyingdowntosleepatnight.Now,atage38,hehastroublewithbalance,gettingupfromachair,andoccasionalurinaryincontinence.Hetakesnarcoticsforchronicbackpain.
患者自称年轻时是出色的运动员，但随时间流逝功能状态慢慢下降。患者27岁时首次注意到自己的无力症状，当时他意识到不能再像以前跳那么高了。随后由于双侧髋部无力和气短开始爬楼困难。30岁时开始行走费力偶有跌倒。34岁时他注意到自己夜间平卧睡觉时感觉憋气。如今38岁，出现平衡障碍，从椅子上站起困难，偶有尿失禁。由于慢性背痛服用*麻药品。
Thepatientdeniedchestpain,wheezing,pleurisy,legpain,fever,chills,weightlossorgain,increasedsputumproduction,nausea,vomiting,anddiaphoresis.Healsodeniedbloodloss,melena,andtremors
患者否认胸痛、喘息、胸膜炎、腿痛、发热、寒战、体重减轻或增加、痰多、恶心、呕吐和出汗。他也否认失血、黑便和震颤。
Atthetimeofneurologicexamination,thepatientwasunablestandandwalkwithoutassistance.MusclestrengthtestingusingtheMedicalResearchCouncilscalegradedright/leftshowedshoulderabduction4/4,hipflexion2/2,kneeextension3/3,andkneeflexion3/3.Thedeeptendonreflexesatthebiceps,triceps,brachioradialis,knee,andanklewere2+bilaterally.Therestoftheexamination,includingthesensoryexamination,wasnormal.
行神经系统检查时，患者不经协助无法站立和行走。医学研究委员会量表分级右侧/左侧的肌力为：肩外展4/4级，屈髋2/2级，伸膝3/3级，屈膝3/3级。双侧肱二头肌、肱三头肌、肱桡肌、膝和踝深部腱反射2+。其余检查正常，包括感觉检查正常。
Questionsforconsideration:
1.Whatisthedifferentialdiagnosisforhypercapnicrespiratoryfailureandmuscleweakness?
2.Wheredotheneurologicdeficitslocalize?
思考问题：
1、高碳酸血症性呼衰和肌无力的鉴别诊断有什么？
2、神经系统病变定位在哪？
SECTION2第二部分Hypercapnicrespiratoryfailurecanbecausedbymedicalconditions,neurologicconditions,orboth.Itcanalsobeprecipitatediatrogenicallybytreatingsomepatients’lungdiseasewithnasaloxygen,whichcansuppresstherespiratorydrive.
内科疾病、神经系统疾病或两者共存都可引起高碳酸血症性呼吸衰竭。鼻导管吸氧治疗某些患者肺疾病时，可抑制呼吸驱动，医源性的逐渐引发此种呼衰。
Ingeneral,medicalcausesofhypercapnicrespiratoryfailureareruledoutquicklybyassessingresponsetonasalO2,PFTs,ABG,andchestimaging.
一般情况下通过评估对鼻吸氧的反应、肺功能检查、动脉血气分析和胸部影像学可以迅速排除引起高碳酸血症性呼吸衰竭的内科原因。
Neurologicconditionsthatcausehypercapnicrespiratoryfailurecanbedividedintocentralandperipheraldisorders.Centralcausescanresultfromstructurallesions(e.g.,brainstemtumor)ortoxicmetabolicstates(e.g.,narcoticoverdose),whereasneuromuscularconditionsareclassifiedasperipheral.Inneuromusculardisease,therespiratoryrateisusuallyincreasedandbreathingisshallowwhileincentralcausestherespiratoryrateisdecreased,erratic,orboth.
引起高碳酸血症性呼吸衰竭的神经系统疾病可以分为中枢性和外周性疾病。中枢性原因可由于结构性病变（如脑干肿瘤）或中*代谢性状态（如*麻剂过量），而神经肌肉疾病被划归周围性因素中。神经肌肉疾病中，呼吸频率通常增快且呼吸浅表，而中枢性原因中呼吸频率减慢、不规则或两者并存。
Neuromuscularconditionsthatcancausehypercapnicrespiratoryfailureinadultsarelistedinthetable.Thosecanbeclassifiedintodiseasesthataffecttheanteriorhorncells,therootsandnerves,theneuromuscularjunction,andmyopathies.Theproximalweaknessonexaminationwithpreservationofsensationandreflexesissuggestiveofamyopathy.Giventhelocalization,aninheritedmyopathyisthemostprobablediagnosisinthesettingoftheslowlyprogressiveandnonfluctuatingproximalweakness.Oftheinheritedmyopathies,Pompedisease,limbgirdlemusculardystrophy2I(LGMD2I),hereditarymyopathywithearlyrespiratoryfailure(HMERF),myotilinopathy,andoccasionallylimb-girdlemusculardystrophy2Aandlimb-girdlemusculardystrophy2C–2Fcanallproduceproximalweaknessandrespiratoryfailure.HMERF,Pompe,andLGMD2Iaremorelikelytoinvolverespiratoryfailurewhenthepatientisstillambulatory