呼吸力学的知识课件

机械通气的呼吸力学

Respiratorymechanicsofmechanicalventilation

WWWXiangyuZhang,MD,FCCP张翔宇SICUShanghaiTenthPeople’sHospitalShanghaiTongjiUniversityShanghai,China呼吸机波形与参数压力－pressure近端压力远端压力气管内压力食管压力，内源性PEEP容量－volume，压力-容量环流量－flow，流速-容量环呼吸做功，等基本图形FlowVolumePressureP-VloopF-Vloop各压力参数

吸气峰压（PIP）

PIP=PRAW+Pplateau

平台压（

Pplateau）

Pplateau=VT/CRS

呼气末压（EEP）气道阻压（PRAW）

PRAW=RAW

×（flowrate）呼吸力学监测顺应性（Compliance）

静态顺应性（Cst

）Cst=VT/（Pplateau—PEEP）

动态顺应性(Cdyn)Cdyn=VT/（PIP—PEEP）

气道阻力(RAW)

RAW=PRAW/(flowrate):2~3(cmH2OL/s)

包括呼吸道与气管导管的阻力AirwayPressure(VCV)AirwayPressure(VCV)压力WhySpontaneousBreathShouldBeNeeded

BettercardiacoutputBetterventilation/perfusionBetterendexpiratorylungvolume(EELV)BetterclinicaloutcomeCurrentOpinioninCriticalCare2005,11:63–68ChristianPutensenAugust,2006CurrentOpinioninCriticalCare2002,8:51–57FabryChest1995:107:1387Asynchronyisstillaproblem

Patient-ventilatorasynchronyduringassistedmechanicalventilation

ArnaudW.ThillePabloRodriguezBelenCabelloFrançoisLelloucheLaurentBrochard

IntensiveCareMed(2006)32:1515–1522TiinPSVInspirationterminationCriteria(Esens)25%ofpeakflowinmostcases压力上升时间与吸气终止OvershootsupraplateauIntrathoracicpressuresTRACHEALPRESSUREPROX.AIRWAYPRESSUREPLEURALPRESSUREALVEOLARPRESSURERespLab@MGHAsiaVentForum@ShanghaiTCI

亚洲通气论坛

OurstudysettingsPressureSupportPcircuitPesoPpluralRisetime1%PcircuitPesoPpluralRisetime1%PcircuitPesoPpluralRisetime100%PcircuitPesoPpluralEsens1%PcircuitPesoPpluralEsophagealBalloonApproximatespleuralpressurePolyethylene10cmlongballoon100cmlongtubingPositionedinthelower1/3oftheesophagusFilledwith0.5-1.0ccairProperplacementoftheballoonisimperativeforaccuratemeasurements.Anapproximatelevelofplacementcanbemadebymeasuringthedistancefromthetipofthenosetothebottomoftheearlobeandthenfromtheearlobetothedistaltipofthexiphoidprocess.BaydurMethod,toconfirmballoonplacementCalculationsbasedondifferentialpressuresTrachealPressureMeasurementsIntendedtypicallyforintermittentuseMoreaccuratelydisplaysactualpressurestransmittedtotheairwaysProvidesabilitytomeasureimposedWorkandResistanceTrachealPressuresMeasurespressureatdistalendofendotrachealtube5FrpolyethylenetubePAW-PTR/Flow(L/s)=ResistanceofETTAdvanceTrachealPressurecatheterto1cmlessthanETplusadaptersWithdraw1-2cmifpatientcontinuestocoughEvaluationofpressure/volumeloopsbasedonintratrachealpressuremeasurementsduringdynamicconditions;S.Karasonetal,Acta

AnesthesiolScand2000;44:571-577Evaluationofpressure/volumeloopsbasedonintratrachealpressuremeasurementsduringdynamicconditions;S.Karasonetal,Acta

AnesthesiolScand2000;44:571-577TidalvolumeremainsconstantAsI:Eratioischanged,autoPEEPisseenonlywithtrachealpressuresPIPincreasesandCompliancedecreasesTC,气道阻力与流速的关系7.5mm导管两端压力差TC/ATCATCHaberthurICM1999;25:514Doesthetube-compensationfunctionoftwomodernmechanical

ventilatorsprovideeffectiveworkofbreathingrelief?CriticalCareOctober2003Vol7No5Maedaetal.TC100%,ETT6.5mmPcircuitPesoPplural气管压力监测设计为间断性监测更准确地显示气管内压力能够监测做功与阻力

Ptr(trachealpressure)作为压力控制呼吸的向导在压力控制通气时，由于气管内插管造成的气流阻力升高，导致肺内压力达不到理想水平AVEA可以测量气管内压力，并作为一条曲线显示。吸气压力可以根据气管内压进行调节Paw=28Ptr=25

Ptr(trachealpressure)作为压力控制呼吸的向导用气管压和食道压计算力学负担为何测量呼吸功?WOBpt测定病人实际的呼吸功水平正常.3-.6Joules/Liter<.3病人做功太低，废用性萎缩>.75病人可能出现疲劳长期机械通气病人脱机成功的关键是能否为他们提供一个正常的呼吸功MacIntyre;CritCareMed1999;27:1040机器支持的力度应根据病人呼吸功来调节AVEA可以提供此类数据用气管压和食道压计算力学负担用气管压和食道压计算力学负担用气管压和食道压计算力学负担4/18/2024Real-timeassessmentofWOB.Pt=25%ofworkVent=75%ofworkEffortisamplifiedbyafactorof4withaproportionalityratioof3:1%Supp75%PAV™+SoftwareOptionClinicalDescriptionD.Georgopoulos,IntensiveCareMed.2008Jul8.FlowAirwayPressureAutoPEEP(AirTrapping)StaticPEEPi

End-ExpiratoryHoldExpHoldExpHoldSetPEEP=0cmH2OStaticPEEPiStaticPEEPiFlowAirwayPressureProblemswithautoPEEPexpiratoryholdmeasurementsWillnotworkifpatientisbreathingspontaneouslyWillnotworkifpatienthassmallairwayclosure,(flowdependentairways)Falsenegatives1.PatienttriggerworkbeforePEEPapplied2.NotePEEPapplication3.PatienttriggerworkafterPEEPapplied监测由于气流受限而引起的内源性PEEP而增加的触发功F-VloopF-Vloopandleaking漏气Leak,漏气SIMV+PSV，通气管路存在漏气AutoPEEPMIP测量---定义MIP(MaximumInspiratoryPressure，最大吸气压)/P100，测量病人在自主呼吸状态下，压力曲线上的负向最大值。MIP测量---意义正常值:成人<-70to-100cmH2O

儿童<-20to-100cmH2O

脱机标准

<-20cmH2O意义:病人的呼吸力量参数.病人吸气肌力量的标志物.作为脱机以及评价神经肌肉疾病进展情况的标准.在脊柱后侧突，老年，COPD以及神经肌肉疾病的病人会其绝对值会降低。P100测量---定义呼吸驱动

(P100),探测到病人吸气努力开始计算，第一个100ms内所形成的最大吸气负压。P100测量---正常值及意义正常值:成人-1to-4cmH2O

儿童-0.5to-4cmH2O注意:在吸气已经启动，而吸气阀仍处于关闭状态的前100ms所产生的压力。

正常情况下，病人感知气路阻塞所需要的时间为

300ms，因此，P100是一个很好的测量呼吸中枢驱动力信号的输出指标。

在最初的这300ms时间里，肺容量和气体流量没有改变，因此，肺脏力学的异常对本指标的测量没有影响。超过-5cmH2O意味着呼吸驱动过高，可能会增加呼吸功并导致呼吸肌疲劳。Intra-thoracicpressureswhileplayingmusicalinstruments

Trans-pulmonaryPressuresEsophagealballoonpressuresreflectpleuralpressuresPleuralpressurescanindicateexternalpressuresworkingagainstthelungTrans-pulmonarypressurescanhelpusdeterminesafeventilationandeffectivePEEPNumericalAssessments–Paw,Pes,Ptp–Insp&ExpHolds

Trans-pulmonary

InspiratoryPlateau:Obtainalveolardistending(Paw)andchestwall(Pes)pressuresPaw–Pes

producestheTrans-pulmonaryPlateauPressureThesemeasurementsaredonebyperforminganinspiratoryholdNumericalAssessments–

Trans-pulmonaryInspPlateauThepressurestryingtoexpandthelungaremetbytheincreasedelasticforcesofthechestwallresistingexpansion3939303030Theinspiratorytrans-pulmonaryplateaupressureof9cmH2OisthepressurebeingexertedacrossthealveolarwallNumericalAssessments–Paw,Pes,Ptp–Insp&ExpHoldsTrans-pulmonaryExpiratoryPlateau:Measuringthepressuresoflungrecruitment–AirwayPEEPandthepressuresofde-recruitment–EsophagealPEEPThesemeasurementsaredonebyperforminganexpiratoryholdChestwallorLung?SimilarairwaypressurecurvesCurveonleftislimitedbychestwallCurveonrightislimitedbylungdiseaseRecruitmentManeuverLungProtectiveStrategy1. SetPplatbelowtheupperPflextoavoidregionaloverdistensionApplysmallVttominimizestretchingforcesSetPEEPatleveltoavoidalveolarcollapseVolumePressureRespiratoryMechanicsinARF*Reducedrangeofvolumeexcursion:LowcomplianceFlatteningatlowandhighvolumes:Lowerandupperinflectionpoints*Bigatello:BrJAnaest1996VolumePressureNORMALARDSP-VloopPflex测量测量完成后，屏幕会自动冻结。如欲重新测量，按压冻结键解冻，屏幕恢复到测量屏幕。InflectionpointRecruitmentManeuverandPVcurvehysteresisAirwayPressure[cmH2O]

%Opening

and

Closing

Pressures0510152025303540455001020304050

OpeningpressureClosingpressure5patients,ALI/ARDSAmJRespir

CritCareMed

Vol164.pp131–140,2001Marini&GattinoniP-Vcurve

MethodologyThesupersyringetechniqueRecruitmentmaneuverisneeded

MethodologySustainedinflation

StepwiseRecruitmentStrategyPressurecontrolwithproneposition,withHFOV,etalTitratingPEEPdeflexafterRMPVcurve(lookingforPdeflex)Oxygenation(PaO2drop>10%)StressIndexPVslopeTitratingPEEPfellowingRM

Pdeflex+2cmH2O,(PVcurve)

Super-syringeLow-flowMultipleocclusionStressIndexLow-flowforbothlimb(inflation&deflation)OxygenationPaO2drop>10%PVslope吸入和呼出均保持流量恒定与超级注射器法的良好相关性消除了阻力造成的影响低流量PV环测定

-准确的恒定低流量PEEP的设置，传统的方法:Amato[1],Takeuchi[2],Matamis[3],Moloneyetal.[4]PEEP的设置，最近的方法:Mehtaetal.[5],Kallet[6],Hickling[7],Harris[8],Bugedo[9],Arnold[10],Pelosi[11],Rimensberger[12]过度膨胀或复张的结束?Hickling[13],Jonson[14],Maggiore[15],Moloneyetal.[5]低流量PV环测定选择吸气和/或呼气枝仅吸气枝

以预设低流量进行充气；当达到压力或容量限制时 （以先到的为准），压力将以5cmH2O/秒的速度降低(避免心脏过负荷)

吸气和呼气枝以预设低流量进行充气和放气；当达到压力或容量限制时，充气转为放气。低流量PV环测定-灵活设置PVcurveforPdeflex

Recognizable?Andpercentageofthem?IsthisPdeflexconstantovertime?OrRM?IsPdeflexafterRMrepeatable?IsPEEPonPdeflexclinicallypractical?NotansweredyetPflex“maximumdifferenceof11cmH2Oforthesamepatient”AMJRESPIRCRITCAREMED2000;161:432–439.R.SCOTTHARRIS,DEANR.HESS,andJOSÉG.VENEGASEffectofthechestwallonpressure–volume