呼吸力學的知識課件

機械通氣的呼吸力學

Respiratorymechanicsofmechanicalventilation

WWWXiangyuZhang,MD,FCCP張翔宇SICUShanghaiTenthPeople’sHospitalShanghaiTongjiUniversityShanghai,China呼吸機波形與參數(shù)壓力－pressure近端壓力遠端壓力氣管內(nèi)壓力食管壓力，內(nèi)源性PEEP容量－volume，壓力-容量環(huán)流量－flow，流速-容量環(huán)呼吸做功，等基本圖形FlowVolumePressureP-VloopF-Vloop各壓力參數(shù)

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）呼吸力學監(jiān)測順應性（Compliance）

靜態(tài)順應性（Cst

）Cst=VT/（Pplateau—PEEP）

動態(tài)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AirwayPressure(VCV)AirwayPressure(VCV)壓力WhySpontaneousBreathShouldBeNeeded

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

Patient-ventilatorasynchronyduringassistedmechanicalventilation

ArnaudW.ThillePabloRodriguezBelenCabelloFran?oisLelloucheLaurentBrochard

IntensiveCareMed(2006)32:1515–1522TiinPSVInspirationterminationCriteria(Esens)25%ofpeakflowinmostcases壓力上升時間與吸氣終止OvershootsupraplateauIntrathoracicpressuresTRACHEALPRESSUREPROX.AIRWAYPRESSUREPLEURALPRESSUREALVEOLARPRESSURERespLab@MGHAsiaVentForum@ShanghaiTCI

亞洲通氣論壇

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,氣道阻力與流速的關(guān)系7.5mm導管兩端壓力差TC/ATCATCHaberthurICM1999;25:514Doesthetube-compensationfunctionoftwomodernmechanical

ventilatorsprovideeffectiveworkofbreathingrelief?CriticalCareOctober2003Vol7No5Maedaetal.TC100%,ETT6.5mmPcircuitPesoPplural氣管壓力監(jiān)測設計為間斷性監(jiān)測更準確地顯示氣管內(nèi)壓力能夠監(jiān)測做功與阻力

Ptr(trachealpressure)作為壓力控制呼吸的向?qū)г趬毫刂仆鈺r，由于氣管內(nèi)插管造成的氣流阻力升高，導致肺內(nèi)壓力達不到理想水平AVEA可以測量氣管內(nèi)壓力，并作為一條曲線顯示。吸氣壓力可以根據(jù)氣管內(nèi)壓進行調(diào)節(jié)Paw=28Ptr=25

Ptr(trachealpressure)作為壓力控制呼吸的向?qū)в脷夤軌汉褪车缐河嬎懔W負擔為何測量呼吸功?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(xiàn)疲勞長期機械通氣病人脫機成功的關(guān)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(jù)病人呼吸功來調(diào)節(jié)AVEA可以提供此類數(shù)據(jù)用氣管壓和食道壓計算力學負擔用氣管壓和食道壓計算力學負擔用氣管壓和食道壓計算力學負擔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監(jiān)測由于氣流受限而引起的內(nèi)源性PEEP而增加的觸發(fā)功F-VloopF-Vloopandleaking漏氣Leak,漏氣SIMV+PSV，通氣管路存在漏氣AutoPEEPMIP測量---定義MIP(MaximumInspiratoryPressure，最大吸氣壓)/P100，測量病人在自主呼吸狀態(tài)下，壓力曲線上的負向最大值。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(shù).病人吸氣肌力量的標志物.作為脫機以及評價神經(jīng)肌肉疾病進展情況的標準.在脊柱后側(cè)突，老年，COPD以及神經(jīng)肌肉疾病的病人會其絕對值會降低。P100測量---定義呼吸驅(qū)動

(P100),探測到病人吸氣努力開始計算，第一個100ms內(nèi)所形成的最大吸氣負壓。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(jīng)啟動，而吸氣閥仍處于關(guān)閉狀態(tài)的前100ms所產(chǎn)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(qū)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(qū)動過高，可能會增加呼吸功并導致呼吸肌疲勞。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測量測量完成后，屏幕會自動凍結(jié)。如欲重新測量，按壓凍結(jié)鍵解凍，屏幕恢復到測量屏幕。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與超級注射器法的良好相關(guān)性消除了阻力造成的影響低流量PV環(huán)測定

-準確的恒定低流量PEEP的設置，傳統(tǒng)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(jié)束?Hickling[13],Jonson[14],Maggiore[15],Moloneyetal.[5]低流量PV環(huán)測定選擇吸氣和/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(zhuǎn)為放氣。低流量PV環(huán)測定-靈活設置PVcurveforPdeflex

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