機械通氣的呼吸力學

Respiratorymechanicsofmechanicalventilation

WWWXiangyuZhang,MD,FCCP張翔宇SICUShanghaiTenthPeople’sHospitalShanghaiTongjiUniversityShanghai,China呼吸力學的知識呼吸機波形與參數壓力－pressure近端壓力遠端壓力氣管內壓力食管壓力，內源性PEEP容量－volume，壓力-容量環流量－flow，流速-容量環呼吸做功，等呼吸力學的知識基本圖形FlowVolumePressure呼吸力學的知識P-VloopF-Vloop呼吸力學的知識各壓力參數

吸氣峰壓（PIP）

PIP=PRAW+Pplateau

平臺壓（Pplateau）

Pplateau=VT/CRS

呼氣末壓（EEP）氣道阻壓（PRAW）

PRAW=RAW

×（flowrate）呼吸力學的知識呼吸力學監測順應性（Compliance）

靜態順應性（Cst）Cst=VT/（Pplateau—PEEP）動態順應性(Cdyn)Cdyn=VT/（PIP—PEEP）

氣道阻力(RAW)

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

包括呼吸道與氣管導管的阻力呼吸力學的知識AirwayPressure(VCV)呼吸力學的知識AirwayPressure(VCV)呼吸力學的知識壓力呼吸力學的知識WhySpontaneousBreathShouldBeNeededBettercardiacoutputBetterventilation/perfusionBetterendexpiratorylungvolume(EELV)Betterclinicaloutcome呼吸力學的知識CurrentOpinioninCriticalCare2005,11:63–68呼吸力學的知識ChristianPutensenAugust,2006呼吸力學的知識CurrentOpinioninCriticalCare2002,8:51–57呼吸力學的知識FabryChest1995:107:1387呼吸力學的知識Asynchronyisstillaproblem

Patient-ventilatorasynchronyduringassistedmechanicalventilation

ArnaudW.ThillePabloRodriguezBelenCabelloFran?oisLelloucheLaurentBrochard

IntensiveCareMed(2006)32:1515–1522呼吸力學的知識呼吸力學的知識呼吸力學的知識TiinPSVInspirationterminationCriteria(Esens)25%ofpeakflowinmostcases呼吸力學的知識壓力上升時間與吸氣終止Overshootsupraplateau呼吸力學的知識IntrathoracicpressuresTRACHEALPRESSUREPROX.AIRWAYPRESSUREPLEURALPRESSUREALVEOLARPRESSURE呼吸力學的知識呼吸力學的知識RespLab@MGH呼吸力學的知識AsiaVentForum@ShanghaiTCI

呼吸力學的知識亞洲通氣論壇

呼吸力學的知識Ourstudysettings呼吸力學的知識PressureSupportPcircuitPesoPplural呼吸力學的知識Risetime1%PcircuitPesoPplural呼吸力學的知識Risetime1%PcircuitPesoPplural呼吸力學的知識Risetime100%PcircuitPesoPplural呼吸力學的知識Esens1%PcircuitPesoPplural呼吸力學的知識EsophagealBalloonApproximatespleuralpressurePolyethylene10cmlongballoon100cmlongtubingPositionedinthelower1/3oftheesophagusFilledwith0.5-1.0ccair呼吸力學的知識Properplacementoftheballoonisimperativeforaccuratemeasurements.Anapproximatelevelofplacementcanbemadebymeasuringthedistancefromthetipofthenosetothebottomoftheearlobeandthenfromtheearlobetothedistaltipofthexiphoidprocess.呼吸力學的知識BaydurMethod,toconfirmballoonplacement呼吸力學的知識Calculationsbasedondifferentialpressures呼吸力學的知識TrachealPressureMeasurementsIntendedtypicallyforintermittentuseMoreaccuratelydisplaysactualpressurestransmittedtotheairwaysProvidesabilitytomeasureimposedWorkandResistance呼吸力學的知識TrachealPressuresMeasurespressureatdistalendofendotrachealtube5FrpolyethylenetubePAW-PTR/Flow(L/s)=ResistanceofETTAdvanceTrachealPressurecatheterto1cmlessthanETplusadaptersWithdraw1-2cmifpatientcontinuestocough呼吸力學的知識Evaluationofpressure/volumeloopsbasedonintratrachealpressuremeasurementsduringdynamicconditions;S.Karasonetal,ActaAnesthesiolScand2000;44:571-577呼吸力學的知識Evaluationofpressure/volumeloopsbasedonintratrachealpressuremeasurementsduringdynamicconditions;S.Karasonetal,ActaAnesthesiolScand2000;44:571-577TidalvolumeremainsconstantAsI:Eratioischanged,autoPEEPisseenonlywithtrachealpressuresPIPincreasesandCompliancedecreases呼吸力學的知識TC,氣道阻力與流速的關系7.5mm導管兩端壓力差呼吸力學的知識TC/ATC呼吸力學的知識ATC呼吸力學的知識HaberthurICM1999;25:514呼吸力學的知識Doesthetube-compensationfunctionoftwomodernmechanical

ventilatorsprovideeffectiveworkofbreathingrelief?CriticalCareOctober2003Vol7No5Maedaetal.呼吸力學的知識TC100%,ETT6.5mmPcircuitPesoPplural呼吸力學的知識氣管壓力監測設計為間斷性監測更準確地顯示氣管內壓力能夠監測做功與阻力呼吸力學的知識Ptr(trachealpressure)作為壓力控制呼吸的向導在壓力控制通氣時，由于氣管內插管造成的氣流阻力升高，導致肺內壓力達不到理想水平AVEA可以測量氣管內壓力，并作為一條曲線顯示。吸氣壓力可以根據氣管內壓進行調節呼吸力學的知識Paw=28Ptr=25Ptr(trachealpressure)作為壓力控制呼吸的向導呼吸力學的知識用氣管壓和食道壓計算力學負擔為何測量呼吸功?呼吸力學的知識WOBpt測定病人實際的呼吸功水平正常.3-.6Joules/Liter<.3病人做功太低，廢用性萎縮>.75病人可能出現疲勞長期機械通氣病人脫機成功的關鍵是能否為他們提供一個正常的呼吸功MacIntyre;CritCareMed1999;27:1040機器支持的力度應根據病人呼吸功來調節AVEA可以提供此類數據用氣管壓和食道壓計算力學負擔呼吸力學的知識用氣管壓和食道壓計算力學負擔呼吸力學的知識用氣管壓和食道壓計算力學負擔呼吸力學的知識Real-timeassessmentofWOB.Pt=25%ofworkVent=75%ofworkEffortisamplifiedbyafactorof4withaproportionalityratioof3:1%Supp75%PAV?+SoftwareOptionClinicalDescription呼吸力學的知識D.Georgopoulos,IntensiveCareMed.2008Jul8.呼吸力學的知識FlowAirwayPressureAutoPEEP(AirTrapping)呼吸力學的知識StaticPEEPi

End-ExpiratoryHoldExpHoldExpHoldSetPEEP=0cmH2OStaticPEEPiStaticPEEPiFlowAirwayPressure呼吸力學的知識ProblemswithautoPEEPexpiratoryholdmeasurementsWillnotworkifpatientisbreathingspontaneouslyWillnotworkifpatienthassmallairwayclosure,(flowdependentairways)Falsenegatives呼吸力學的知識1.PatienttriggerworkbeforePEEPapplied2.NotePEEPapplication3.PatienttriggerworkafterPEEPapplied監測由于氣流受限而引起的內源性PEEP而增加的觸發功呼吸力學的知識F-Vloop呼吸力學的知識F-Vloopandleaking漏氣呼吸力學的知識Leak,漏氣SIMV+PSV，通氣管路存在漏氣呼吸力學的知識呼吸力學的知識呼吸力學的知識AutoPEEP呼吸力學的知識MIP測量---定義MIP(MaximumInspiratoryPressure，最大吸氣壓)/P100，測量病人在自主呼吸狀態下，壓力曲線上的負向最大值。呼吸力學的知識MIP測量---意義正常值:成人<-70to-100cmH2O

兒童<-20to-100cmH2O

脫機標準<-20cmH2O意義:病人的呼吸力量參數.病人吸氣肌力量的標志物.作為脫機以及評價神經肌肉疾病進展情況的標準.在脊柱后側突，老年，COPD以及神經肌肉疾病的病人會其絕對值會降低。呼吸力學的知識P100測量---定義呼吸驅動(P100),探測到病人吸氣努力開始計算，第一個100ms內所形成的最大吸氣負壓。呼吸力學的知識P100測量---正常值及意義正常值:成人-1to-4cmH2O

兒童-0.5to-4cmH2O注意:在吸氣已經啟動，而吸氣閥仍處于關閉狀態的前100ms所產生的壓力。正常情況下，病人感知氣路阻塞所需要的時間為300ms，因此，P100是一個很好的測量呼吸中樞驅動力信號的輸出指標。在最初的這300ms時間里，肺容量和氣體流量沒有改變，因此，肺臟力學的異常對本指標的測量沒有影響。超過-5cmH2O意味著呼吸驅動過高，可能會增加呼吸功并導致呼吸肌疲勞。呼吸力學的知識Intra-thoracicpressureswhileplayingmusicalinstruments

呼吸力學的知識Trans-pulmonaryPressuresEsophagealballoonpressuresreflectpleuralpressuresPleuralpressurescanindicateexternalpressuresworkingagainstthelungTrans-pulmonarypressurescanhelpusdeterminesafeventilationandeffectivePEEP呼吸力學的知識呼吸力學的知識NumericalAssessments–Paw,Pes,Ptp–Insp&ExpHolds

Trans-pulmonary

InspiratoryPlateau:Obtainalveolardistending(Paw)andchestwall(Pes)pressuresPaw–PesproducestheTrans-pulmonaryPlateauPressureThesemeasurementsaredonebyperforminganinspiratoryhold呼吸力學的知識NumericalAssessments–

Trans-pulmonaryInspPlateauThepressurestryingtoexpandthelungaremetbytheincreasedelasticforcesofthechestwallresistingexpansion3939303030Theinspiratorytrans-pulmonaryplateaupressureof9cmH2Oisthepressurebeingexertedacrossthealveolarwall呼吸力學的知識NumericalAssessments–Paw,Pes,Ptp–Insp&ExpHoldsTrans-pulmonaryExpiratoryPlateau:Measuringthepressuresoflungrecruitment–AirwayPEEPandthepressuresofde-recruitment–EsophagealPEEPThesemeasurementsaredonebyperforminganexpiratoryhold呼吸力學的知識ChestwallorLung?SimilarairwaypressurecurvesCurveonleftislimitedbychestwallCurveonrightislimitedbylungdisease呼吸力學的知識RecruitmentManeuver呼吸力學的知識LungProtectiveStrategy1. SetPplatbelowtheupperPflextoavoidregionaloverdistensionApplysmallVttominimizestretchingforcesSetPEEPatleveltoavoidalveolarcollapseVolumePressure呼吸力學的知識RespiratoryMechanicsinARF*Reducedrangeofvolumeexcursion:LowcomplianceFlatteningatlowandhighvolumes:Lowerandupperinflectionpoints*Bigatello:BrJAnaest1996VolumePressureNORMALARDS呼吸力學的知識P-Vloop呼吸力學的知識Pflex測量測量完成后，屏幕會自動凍結。如欲重新測量，按壓凍結鍵解凍，屏幕恢復到測量屏幕。呼吸力學的知識Inflectionpoint呼吸力學的知識RecruitmentManeuverandPVcurvehysteresis呼吸力學的知識AirwayPressure[cmH2O]

%Opening

and

Closing

Pressures0510152025303540455001020304050

OpeningpressureClosingpressure5patients,ALI/ARDSAmJRespirCritCareMed

Vol164.pp131–140,2001Marini&Gattinoni呼吸力學的知識P-VcurveMethodology呼吸力學的知識Thesupersyringetechnique呼吸力學的知識RecruitmentmaneuverisneededMethodologySustainedinflation

StepwiseRecruitmentStrategyPressurecontrolwithproneposition,withHFOV,etalTitratingPEEPdeflexafterRMPVcurve(lookingforPdeflex)Oxygenation(PaO2drop>10%)StressIndexPVslope呼吸力學的知識TitratingPEEPfellowingRMPdeflex+2cmH2O,(PVcurve)Super-syringeLow-flowMultipleocclusionStressIndexLow-flowforbothlimb(inflation&deflation)OxygenationPaO2drop>10%PVslope呼吸力學的知識吸入和呼出均保持流量恒定與超級注射器法的良好相關性消除了阻力造成的影響低流量PV環測定

-準確的恒定低流量呼吸力學的知識PEEP的設置，傳統的方法:Amato[1],Takeuchi[2],Matamis[3],Moloneyetal.[4]PEEP的設置，最近的方法:Mehtaetal.[5],Kallet[6],Hickling[7],Harris[8],Bugedo[9],Arnold[10],Pelosi[11],Rimensberger[12]過度膨脹或復張的結束?Hickling[13],Jonson[14],Maggiore[15],Moloneyetal.[5]低流量PV環測定呼吸力學的知識選擇吸氣和/或呼氣枝僅吸氣枝

以預設低流量進行充氣；當達到壓力或容量限制時 （以先到的為準），壓力將以5cmH2O/秒的速度降低(避免心臟過負荷)

吸氣和呼氣枝以預設低流量進行充氣和放氣；當達到壓力或容量限制時，充氣轉為放氣。低流量PV環測定-靈活設置呼吸力學的知識PVcurveforPdeflexRecognizable?Andpercentageofthem?IsthisPdeflexconstantovertime?OrRM?IsPdeflexafterRMrepeatable?IsPEEPonPdeflexclinicallypractical?Notansweredyet呼吸力學的知識Pflex“maximumdifferenceof11cmH2Oforthesamepatient”AMJRESPIRCRITCAREMED2000;161:432–439.R.SCOTTHARRIS,DEANR.HESS,andJOSéG.VENEGAS呼吸力學的知識Effectofthechestwallonpressure–volumecur