The document discusses various modes of mechanical ventilation. It defines key characteristics of ventilation modes including the control variable, breath sequence, control type, and specific control strategies. Pressure control and volume control modes are described and compared. Graphical representations of common breathing patterns like pressure control-continuous mandatory ventilation are provided. Advanced modes involving automatic adjustments are also outlined, such as adaptive control and intelligent modes using artificial intelligence.

1. MechanicalVentilationUnderstandingModesRobChatburn,RRT-NPS,FAARCResearchManager–RespiratoryTherapyClevelandClinicAssociateProfessorCaseWesternReserveUniversity1

2. Overview•Characteristicsofmodes–Pressurecontrolvsvolumecontrol–Graphicalrepresentationsofmodes•Breathtypes–Mandatoryvsspontanous–Assistedvsunassisted•Breathingpatterns–Definitions,indications,examples–Graphicalrepresentations•Computercontrolofmechanicalventilation2

3. CharacteristicsofaMode1.BreathingPattern––ControlvariableBreathsequence2.ControlType–Setpoint,auto-setpoint,servo,adaptive,optimal3.ControlStrategy––PhasevariablesOperationallogic3

4. ControlVariablesPvent=ExV+RxVVentilatorcancontrolonlyonevariableatatimeIndependentvariableiscontrolvariable4

5. VolumeControl•Tidalvolumeandflowpreset•Airwaypressurechangeswithlungmechanics•Advantage:–Minuteventilationandgasexchangestable•Disadvantage:–Volumeandflowmaynotbeoptimal5

6. PressureControl•Airwaypressurepreset•Volumeandflowchangewithlungmechanics•Advantage:–Betterpatientflowsynchrony–Possiblybetteroxygenation–Potentiallyreducedriskofvolutrauma•Disadvantage:–Gasexchangemaynotbestable6

7. MinuteVolumeVolumeTidalVolumeControlInfluenceDiagramRateCycleTimeI:EInspiratoryTimeExpiratoryTimeInspiratoryFlow7

8. MinuteVentilationResistancePressureTimeConstantVentilatoryFrequencyTidalVolumeControlInfluenceInspiratoryTimeExpiratoryTimeComplianceDiagramI:ERatioPressureGradientContinuousFlowRate(Affectsshapeofpressurewaveform)PeakInspiratoryPressureEndExpiratoryPressureMeanAirwayPressure8

9. Volume/FlowControlPressureControlInspirationExpirationInspirationExpirationPawPressureVolumePawPlungFlowTime(s)Time(s)009

10. DualControl•VolumecontroltoPressureControl:–Attemptstodeliveraconstanttidalvolumewhilelimitingpeakpressure•PressurecontroltoVolumeControl:–Attemptstolimitpeakpressurebutassurestidalvolumedelivery•Disadvantage:–Requireshighdegreeofunderstanding–Difficulttoadjustandmaintain10

11. CharacteristicsofaMode1.BreathingPattern––ControlvariableBreathsequence2.ControlType–Setpoint,auto-setpoint,servo,adaptive,optimal3.ControlStrategy––PhasevariablesOperationallogic11

12. BreathTypesWhatisthedifferencebetweenmandatoryandspontaneousbreaths?12

13. BreathTypesSpontaneousMandatorynonoyesPatientPatientcontrolscontrolsThinkyesstartsize13

14. DefinitionofAssistedBreath•Assisted–Ventilatordoesworkonpatient.•Un-Assisted–Ventilatordoesnoworkonpatient.•Loaded(workimposedonpatient)–Patientdoesworkonventilator.14

15. IdentificationofAssistedBreaths•Assisted–Airwaypressurerisesabovebaselineduringinspiration(orfallsbelowbaselineduringexpiration).•Un-Assisted–Airwaypressurestaysconstantduringinspirationorexpiration.•Loaded(workimposedonpatient)–Airwaypressurefallsbelowbaselineduringinspirationandrisesabovebaselineduringexpiration.15

16. AssistedSpontaneousBreaths•••••PressureSupportVolumeSupportAutomaticTubeCompensationProportionalAssistVentilationSmartCare16

17. PotentialConfusion•Anassistedbreathmaybespontaneousormandatory•Aspontaneousbreathmaybeassistedorunassisted•Amandatorybreathisassistedbydefinition17

18. CharacteristicsofaMode1.BreathingPattern––ControlvariableBreathsequence2.ControlType–Setpoint,auto-setpoint,servo,adaptive,optimal3.ControlStrategy––PhasevariablesOperationallogic18

19. ContinuousMandatoryVentilation(CMV)•Mandatorybreaths–Machinetriggeredand/ormachinecycled•Spontaneousbreaths–Duringmandatorybreathsonly,notbetween•Keyclinicalconcept–Levelofsupportindependentoffrequency(ifpatientisbreathing)19

20. IntermittentMandatoryVentilation(IMV)•Mandatorybreaths–Machinetriggeredand/ormachinecycled•Spontaneousbreaths–Betweenandduringmandatorybreaths•Keyclinicalconcept–Levelofsupportisproportionaltosetfrequency(ifspontaneousbreathsunassisted)–Historicallyusedasamodeofweaning20

21. ContinuousSpontaneousVentilation(CSV)•Allbreathsspontaneous–Patienttriggeredandcycled–Nobackuprateincaseofapnea•Breathsmayormaynotbeassisted–Fullsupportmaybeachieved(ifnoapnea)21

22. CharacteristicsofaMode1.BreathingPattern––ControlvariableBreathsequence2.ControlType–Setpoint,auto-setpoint,servo,adaptive,optimal3.ControlStrategy––PhasevariablesOperationallogic22

23. 8BasicBreathingPatternsControlBreathVariableVolumePressureDualSequenceContinuousMandatoryVentilationIntermittentMandatoryVentilationContinuousMandatoryVentilationIntermittentMandatoryVentilationContinuousSpontaneousVentilationContinuousMandatoryVentilationIntermittentMandatoryVentilationContinuousSpontaneousVentilationSymbolVC-CMVVC-IMVPC-CMVPC-IMVPC-CSVDC-CMVDC-IMVDC-CSV23

24. VC-CMV•Oftenreferredtoas“Assist/Control”•Characteristics–VCresultsinmoreevendistributionofventilationamonglungunitswithequalresistanceandunequalcompliancethanPC–Selectionofflowandsensitivityiscritical•Indications–Needfortotalventilatorysupport–Needforpreciseregulationofbloodgases•Example–PreciseregulationofPaCO2inpatientswithtraumaticbraininjury24

25. ABCPressuresmallinspiratoryeffortlargeinspiratoryeffortnoinspiratoryeffortVC-CMVMusclewaveformsreducedpressureindicatespatienteffortthroughoutinspirationVentilatorPressurepatientmachinesettidalvolumetriggeredtriggeredVolumesetflow25Flow

26. VC-IMV•Characteristics–Spontaneousbreathsmaybeassisted–Selectionofmandatoryflowandspontaneouspressuresupportcritical•Indications–Relativelynormallungfunction–Rapidrecoveryfromsedationorrespiratoryfailure–Recentdatasuggestitisworstchoiceforweaning•Example–TreatmentofneuromusculardiseaselikeGullian-Barresyndrome26

27. ABCVC-IMVwaveformsArespontaneousmediuminspiratoryeffortsetpressuresupportPressuresmallinspiratoryeffortnoinspiratoryeffortMuscleVentilatorPressurebreathsassisted?patientmachinetriggeredtriggeredsettidalvolumeVolumesetflow27Flow

28. PC-CMV•Characteristics–PCresultsinmoreevendistributionofventilationamonglungunitswithequalcomplianceandunequalresistancethanVC–PressurecontrolresultsinhighermeanairwaypressureandearlierlungopeningthanVC•Indications–Problemswithoxygenationorsynchrony•Example–TreatmentofARDSpatientswithoxygenationproblems28

29. ABCPC-CMVwaveformsPressuresmallinspiratoryeffortlargeinspiratoryeffortnoinspiratoryeffortMusclesetpressurelimitVentilatorPressureVolumetimecycledpatienttriggeredFlowmachinetriggered29

30. PC-IMV•Characteristics–Relativelysimplemode–Usedhistoricallyforinfants–Spontaneousbreathsmaybeassisted•Indications–Problemswithoxygenationorsynchrony–Adequateventilatorydrive•Example–TreatmentofprematureinfantswithRDS30

31. ACBPC-IMVwaveformsmediuminspiratoryeffortPressurelargeinspiratoryeffortnoinspiratoryeffortMuscleVentilatorPressureVolumeFlow31

32. PC-CSV•Characteristics–Noassist=CPAP–AssistPressureSupportProportionalAssistAutomaticTubeCompensation•Indications–Weaning–Reduceworkofbreathingorstabilizeoxygenation•Examples–NasalCPAPforneonatesrecoveringfromRDS–Noninvasiveventilationofadults32

33. ABCPressuresmallinspiratoryeffortlargeinspiratoryeffortnoinspiratoryeffortPC-CSVMusclewaveformsSpontaneousbreathsarenotassisted(CPAP)33VentilatorPressureVolumeFlow

34. DC-CMV•Characteristics–Mandatorybreathsadapttochanginglungmechanics•Indications–Unstablelungmechanicsorventilatorydrive•Example–Treatmentofpatientwithpneumoniaandintermittentsecretionproblems34

35. ABnoinspiratoryeffortlargeinspiratoryeffortDC-CMVPressureMusclewaveformspressurelimitsetpressurelimitsetvolumetargetover-riddenvolumetargetpressure-to-volumeBirdVAPSVentilatorPressurevolumecyclednotmetvolumemetbeforeflowdecaystosetlimitVolumeinspiratoryflowequalsflowlimitflowcycledsetflowlimitswitchfrompressurecontroltovolumecontrolFlowpatienttriggered35

36. ABPressureDC-CMVwaveformsvolume-to-pressuresmallinspiratoryeffortplateaupressureMusclesetPmaxVentilatorPressureDrägerPressureLimitedVentilationplateaupressurevolumelimitedtimecycledsettidalvolumevolumelimitedtimecycledVolumeFlowswitchfromvolumecontroltopressurecontrol36

37. ACBDC-IMVPressureMusclewaveformssetPmaxsetPmaxVentilatorPressureplateaupressuresettidalvolumeVolumesetflowtimecycledtimecycledFlow37

38. PressureSupport•Pressureorflowtriggered,pressurelimited,inspiratoryflowcycled•Levelofventilatorysupportdeterminedbypressurelimit•Sometimessettoapproximatelysupportresistiveworkofbreathing(throughendotrachealtube)38

39. ABCPC-CSVwaveformsPressuresmallinspiratoryeffortlargeinspiratoryeffortnoinspiratoryeffortMusclesetpressurelimitVentilatorPressureSpontaneousbreathsareassistedpressurerisetimeincreasedVolumeflowcyclethresholdflowcycledpatienttriggered39Flow

40. ProportionalAssistPmus=Enormal×volume+Rnormal×flowPmus=(Enormal+Eabnormal)×volume+(Rnormal+Rabnormal)×flowPmus=(normalload)+(abnormalload)Pmus+Pvent=(normalload)+(abnormalload)Pvent=abnormalload=Eabnormal×volume+Rabnormal×flowoperatorsettings(volumeandflowamplificationfactors)40

41. ABCPC-CSVsmallinspiratoryeffortlargeinspiratoryeffortnoinspiratoryeffortPressureMusclewaveformsSpontaneousbreathsareassisted(ProportionalAssist)41VentilatorPressureVolumeFlow

42. AutomaticTubeCompensationPvent=abnormalresistiveload=Rtube×flow2operatorsetstubediameterventilatorcalculatesresistancefactor42

43. CharacteristicsofaMode1.BreathingPattern–Controlvariable–Breathsequence2.ControlType–Withinbreaths–Betweenbreaths3.SpecificControlStrategy–Phasevariables–Operationallogic43

44. EvolutionofVentilatorControlTypesTacticalControl(within-breaths)setpoint(PC-IMV)PatientVentilatorOperatorauto-setpoint(Pmax)servo(AutomaticTubeCompensation)operator-selected,staticsetpointsStrategicControl(betweenbreaths)adaptive(CMV+AutoFlow)ModelOperatoroptimal(ASV)ventilator-selected,dynamicsetpointsstaticmodelPatientVentilatorIntelligentControl(betweenpatients)knowledgebasedartificialneuralnetworkventilator-selected,dynamicsetpointsModeldynamicmodelabilitytolearnfromexperiencePatient44Ventilator

45. TacticalControl•Allthemodesdiscussedsofar•Allrequiretheoperatortoset––––Pressure(PIP,PEEP)Volume(tidalvolume,minuteventilation)Flow(peakinspiratoryflow)Time(inspiratorytime,frequency,I:E)45

46. StrategicControl•Characteristics–BreathingpatternmaybePC-CMV,PC-IMV,PC-CSV–Pressurelimitautomaticallyadjustedtocompensateforchangesincompliancetomeettargettidalvolume•Indications–(Self)Weaning–Reduceworkofbreathingorstabilizeoxygenation–Reduceclinicianworkload•Examples–Post-operativepatientswithnormallungs–MixedICUpatients–COPDexacerbation46

47. AnoinspiratoryeffortBCAdaptiveControllargeinspiratoryeffortPressureMusclepressurelimitautomaticallyreducedvolumeovershootvolumetargettimecycledVentilatorPressureVolumeFlowpatienttriggeredmachinetriggered47

48. HamiltonGalileoAdaptiveSupportMode•Optimumcontrol•Clinicianenters–Patientidealbodyweight–Percentofpredictedminuteventilationtosupport•Ventilatormonitorsminuteventilationlungmechanics(expiratorytimeconstant)•Automaticallyadjustsminuteventilationmandatorybreathfrequencypressurelimitinspiratorytime•SetsfrequencytominimizeWOBasifpatientwasbreathingspontaneously48

49. “Anymedicalinstrumentationthatrequiresconstantinputfromahumanoperatorisobsolete”HamiltonMedical49

50. IntelligentControl•Characteristics–ClassificationofpatientconditionManual(eg,bydiagnosis)Fuzzylogic–Rulebasedexpertsystemorartificialneuralnetwork•Indications–Weaning–Respiratoryfailureofvarioustypes–Trauma•Examples–Post-operativepatientswithnormallungs–MixedICUpatients–Emergencydepartment50

51. CommercialExample•SmartCare(DrägerEvitaXL)–KnowledgeBasedControl1.Automaticallyadjustpressuresupport:breathingrate,tidalvolumeandendtidalCO2.2.Automaticallytestpatienttoleranceofalowerpressuresupportlevelwithoutleavingthecomfortzone.3.Attempts“extubation”withPSatresistiveWOB.••Artificialintelligence–Fuzzylogicinterpretspatientcondition–RulebasedexpertsystemtreatsconditionOperatorsets–patientweight–history(neuroorCOPD)–typeofairway51

52. CharacteristicsofaMode1.BreathingPattern–Controlvariable–Breathsequence2.ControlType–Setpoint,auto-setpoint,servo,adaptive,optimalknowledgebased3.SpecificControlStrategy–Phasevariables–Operationallogic52

53. ModeDescriptionUtility•Describethedifferenceinmodes–PressureSupport–VolumeSupport•Describethedifferenceinventilators–Pressuresupport(PB7200)–Pressuresupport(Servo-i)53

54. ModeDescriptionSummary(withoutthebrandjargon)•PressureSupport–OnlyLevel1neededPC-CSV•VolumeSupport–RequiresLevel2PC-CSVwithadaptivecontrol54

55. AdaptivePressureControl••••PressureRegulatedVolumeControlAutoFlowVC+PC-SIMV+VolumeGuarantee55

56. ModeDescriptionSummary(withoutthebrandjargon)•Level3PressureSupport•PB7200–Cannotadjustrisetime(limitvariable)–Cannotadjustcyclethreshold(cyclevariable)•Servo-i–Adjustablerisetime(limitvariable)–Adjustablecyclethreshold(cyclevariable)56

57. Resources•Getthebook–collegeleveltextbook–300pages–www.aarc.org/storeTrainingSoftware–www.VentWorld.com–www.Amazon.com57

58. TooComplicated?58

59. FinalThought“Ifyouexplainsomethingsosimplythatevenafoolcanunderstandit,thenonlyafoolwillunderstandit."FPPrimianoJr59