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. MechanicalVentilation UnderstandingModes RobChatburn,RRT-NPS,FAARC ResearchManager–RespiratoryTherapy ClevelandClinic AssociateProfessor CaseWesternReserveUniversity 1

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

3. CharacteristicsofaMode 1.BreathingPattern – – Controlvariable Breathsequence 2.ControlType – Setpoint,auto-setpoint,servo,adaptive,optimal 3.ControlStrategy – – Phasevariables Operationallogic 3

4. ControlVariables Pvent=ExV+RxV Ventilatorcancontrolonlyonevariableatatime Independentvariableiscontrolvariable 4

5. VolumeControl •Tidalvolumeandflowpreset •Airwaypressurechangeswithlung mechanics •Advantage: –Minuteventilationandgasexchangestable •Disadvantage: –Volumeandflowmaynotbeoptimal 5

6. PressureControl •Airwaypressurepreset •Volumeandflowchangewithlung mechanics •Advantage: –Betterpatientflowsynchrony –Possiblybetteroxygenation –Potentiallyreducedriskofvolutrauma •Disadvantage: –Gasexchangemaynotbestable 6

7. Minute Volume Volume Tidal Volume Control Influence Diagram Rate Cycle Time I:E Inspiratory Time Expiratory Time Inspiratory Flow 7

8. Minute Ventilation Resistance Pressure Time Constant Ventilatory Frequency Tidal Volume Control Influence Inspiratory Time Expiratory Time Compliance Diagram I:ERatio Pressure Gradient Continuous FlowRate (Affectsshape ofpressure waveform) Peak Inspiratory Pressure End Expiratory Pressure Mean Airway Pressure 8

9. Volume/FlowControl PressureControl Inspiration Expiration Inspiration Expiration Paw Pressure Volume Paw Plung Flow Time(s) Time(s) 0 0 9

10. DualControl •VolumecontroltoPressureControl: –Attemptstodeliveraconstanttidalvolumewhile limitingpeakpressure •PressurecontroltoVolumeControl: –Attemptstolimitpeakpressurebutassurestidal volumedelivery •Disadvantage: –Requireshighdegreeofunderstanding –Difficulttoadjustandmaintain 10

11. CharacteristicsofaMode 1.BreathingPattern – – Controlvariable Breathsequence 2.ControlType – Setpoint,auto-setpoint,servo,adaptive,optimal 3.ControlStrategy – – Phasevariables Operationallogic 11

12. BreathTypes Whatisthedifferencebetween mandatoryandspontaneousbreaths? 12

13. BreathTypes Spontaneous Mandatory no no yes Patient Patient controls controls Think yes start size 13

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

15. IdentificationofAssistedBreaths •Assisted –Airwaypressurerisesabovebaselineduring inspiration(orfallsbelowbaselineduring expiration). •Un-Assisted –Airwaypressurestaysconstantduringinspiration orexpiration. •Loaded(workimposedonpatient) –Airwaypressurefallsbelowbaselineduring inspirationandrisesabovebaselineduring expiration. 15

16. AssistedSpontaneousBreaths • • • • • PressureSupport VolumeSupport AutomaticTubeCompensation ProportionalAssistVentilation SmartCare 16

17. PotentialConfusion •Anassistedbreathmaybe spontaneousormandatory •Aspontaneousbreathmaybe assistedorunassisted •Amandatorybreathisassistedby definition 17

18. CharacteristicsofaMode 1.BreathingPattern – – Controlvariable Breathsequence 2.ControlType – Setpoint,auto-setpoint,servo,adaptive,optimal 3.ControlStrategy – – Phasevariables Operationallogic 18

19. ContinuousMandatory Ventilation(CMV) •Mandatorybreaths –Machinetriggeredand/ormachinecycled •Spontaneousbreaths –Duringmandatorybreathsonly,notbetween •Keyclinicalconcept –Levelofsupportindependentoffrequency(if patientisbreathing) 19

20. IntermittentMandatory Ventilation(IMV) •Mandatorybreaths –Machinetriggeredand/ormachinecycled •Spontaneousbreaths –Betweenandduringmandatorybreaths •Keyclinicalconcept –Levelofsupportisproportionaltosetfrequency (ifspontaneousbreathsunassisted) –Historicallyusedasamodeofweaning 20

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

22. CharacteristicsofaMode 1.BreathingPattern – – Controlvariable Breathsequence 2.ControlType – Setpoint,auto-setpoint,servo,adaptive,optimal 3.ControlStrategy – – Phasevariables Operationallogic 22

23. 8BasicBreathingPatterns Control Breath Variable Volume Pressure Dual Sequence ContinuousMandatoryVentilation IntermittentMandatoryVentilation ContinuousMandatoryVentilation IntermittentMandatoryVentilation ContinuousSpontaneousVentilation ContinuousMandatoryVentilation IntermittentMandatoryVentilation ContinuousSpontaneousVentilation Symbol VC-CMV VC-IMV PC-CMV PC-IMV PC-CSV DC-CMV DC-IMV DC-CSV 23

24. VC-CMV •Oftenreferredtoas“Assist/Control” •Characteristics –VCresultsinmoreevendistributionofventilation amonglungunitswithequalresistanceandunequal compliancethanPC –Selectionofflowandsensitivityiscritical •Indications –Needfortotalventilatorysupport –Needforpreciseregulationofbloodgases •Example –PreciseregulationofPaCO2inpatientswithtraumatic braininjury 24

25. A B C Pressure small inspiratory effort large inspiratory effort no inspiratory effort VC-CMV Muscle waveforms reducedpressure indicatespatient effortthroughout inspiration Ventilator Pressure patient machine settidalvolume triggered triggered Volume setflow 25 Flow

26. VC-IMV •Characteristics –Spontaneousbreathsmaybeassisted –Selectionofmandatoryflowandspontaneous pressuresupportcritical •Indications –Relativelynormallungfunction –Rapidrecoveryfromsedationorrespiratoryfailure –Recentdatasuggestitisworstchoiceforweaning •Example –TreatmentofneuromusculardiseaselikeGullian- Barresyndrome 26

27. A B C VC-IMV waveforms Arespontaneous medium inspiratory effort setpressuresupport Pressure small inspiratory effort no inspiratory effort Muscle Ventilator Pressure breathsassisted? patient machine triggered triggered settidalvolume Volume setflow 27 Flow

28. PC-CMV •Characteristics –PCresultsinmoreevendistributionofventilation amonglungunitswithequalcomplianceandunequal resistancethanVC –Pressurecontrolresultsinhighermeanairway pressureandearlierlungopeningthanVC •Indications –Problemswithoxygenationorsynchrony •Example –TreatmentofARDSpatientswithoxygenation problems 28

29. A B C PC-CMV waveforms Pressure small inspiratory effort large inspiratory effort no inspiratory effort Muscle setpressurelimit Ventilator Pressure Volume timecycled patient triggered Flow machine triggered 29

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

31. A C B PC-IMV waveforms medium inspiratory effort Pressure large inspiratory effort no inspiratory effort Muscle Ventilator Pressure Volume Flow 31

32. PC-CSV •Characteristics –Noassist=CPAP –Assist PressureSupport ProportionalAssist AutomaticTubeCompensation •Indications –Weaning –Reduceworkofbreathingorstabilizeoxygenation •Examples –NasalCPAPforneonatesrecoveringfromRDS –Noninvasiveventilationofadults 32

33. A B C Pressure small inspiratory effort large inspiratory effort no inspiratory effort PC-CSV Muscle waveforms Spontaneous breathsarenot assisted (CPAP) 33 Ventilator Pressure Volume Flow

34. DC-CMV •Characteristics –Mandatorybreathsadapttochanginglung mechanics •Indications –Unstablelungmechanicsorventilatorydrive •Example –Treatmentofpatientwithpneumoniaand intermittentsecretionproblems 34

35. A B no inspiratory effort large inspiratory effort DC-CMV Pressure Muscle waveforms pressurelimit setpressurelimit setvolumetarget over-ridden volumetarget pressure-to-volume BirdVAPS Ventilator Pressure volumecycled notmet volumemetbefore flowdecaystosetlimit Volume inspiratoryflow equalsflowlimit flowcycled setflowlimit switchfrompressurecontrol tovolumecontrol Flow patient triggered 35

36. A B Pressure DC-CMV waveforms volume-to-pressure small inspiratory effort plateau pressure Muscle setPmax Ventilator Pressure Dräger PressureLimited Ventilation plateau pressure volumelimited timecycled settidalvolume volume limited timecycled Volume Flow switchfromvolumecontrol topressurecontrol 36

37. A C B DC-IMV Pressure Muscle waveforms setPmax setPmax Ventilator Pressure plateau pressure settidalvolume Volume setflow timecycled timecycled Flow 37

38. PressureSupport •Pressureorflowtriggered,pressure limited,inspiratoryflowcycled •Levelofventilatorysupport determinedbypressurelimit •Sometimessettoapproximately supportresistiveworkofbreathing (throughendotrachealtube) 38

39. A B C PC-CSV waveforms Pressure small inspiratory effort large inspiratory effort no inspiratory effort Muscle setpressurelimit Ventilator Pressure Spontaneous breathsare assisted pressurerise time increased Volume flowcyclethreshold flowcycled patient triggered 39 Flow

40. ProportionalAssist Pmus=Enormal×volume+Rnormal×flow Pmus=(Enormal+Eabnormal)×volume+(Rnormal+Rabnormal)×flow Pmus=(normalload)+(abnormalload) Pmus+Pvent=(normalload)+(abnormalload) Pvent=abnormalload=Eabnormal×volume+Rabnormal×flow operatorsettings(volumeandflowamplificationfactors) 40

41. A B C PC-CSV small inspiratory effort large inspiratory effort no inspiratory effort Pressure Muscle waveforms Spontaneousbreaths areassisted (ProportionalAssist) 41 Ventilator Pressure Volume Flow

42. AutomaticTube Compensation Pvent=abnormalresistiveload=Rtube×flow 2 operatorsetstubediameter ventilatorcalculatesresistancefactor 42

43. CharacteristicsofaMode 1.BreathingPattern –Controlvariable –Breathsequence 2.ControlType –Withinbreaths –Betweenbreaths 3.SpecificControlStrategy –Phasevariables –Operationallogic 43

44. EvolutionofVentilatorControlTypes TacticalControl(within-breaths) setpoint(PC-IMV) Patient Ventilator Operator auto-setpoint(Pmax) servo(AutomaticTubeCompensation) operator-selected,staticsetpoints StrategicControl(betweenbreaths) adaptive(CMV+AutoFlow) Model Operator optimal(ASV) ventilator-selected,dynamicsetpoints staticmodel Patient Ventilator IntelligentControl(betweenpatients) knowledgebased artificialneuralnetwork ventilator-selected,dynamicsetpoints Model dynamicmodel abilitytolearnfromexperience Patient 44 Ventilator

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 –Pressurelimitautomaticallyadjustedtocompensatefor changesincompliancetomeettargettidalvolume •Indications –(Self)Weaning –Reduceworkofbreathingorstabilizeoxygenation –Reduceclinicianworkload •Examples –Post-operativepatientswithnormallungs –MixedICUpatients –COPDexacerbation 46

47. A no inspiratory effort B C Adaptive Control large inspiratory effort Pressure Muscle pressurelimit automaticallyreduced volumeovershoot volumetarget timecycled Ventilator Pressure Volume Flow patient triggered machine triggered 47

48. HamiltonGalileoAdaptiveSupportMode •Optimumcontrol •Clinicianenters –Patientidealbodyweight –Percentofpredictedminuteventilationtosupport •Ventilatormonitors minuteventilation lungmechanics(expiratorytimeconstant) •Automaticallyadjustsminuteventilation mandatorybreathfrequency pressurelimit inspiratorytime •SetsfrequencytominimizeWOBasif patientwasbreathingspontaneously 48

49. “Anymedical instrumentationthat requiresconstant inputfromahuman operatorisobsolete” HamiltonMedical 49

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

51. CommercialExample •SmartCare(DrägerEvitaXL) –KnowledgeBasedControl 1.Automaticallyadjustpressuresupport:breathingrate,tidal volumeandendtidalCO2. 2.Automaticallytestpatienttoleranceofalowerpressure supportlevelwithoutleavingthecomfortzone. 3.Attempts“extubation”withPSatresistiveWOB. • • Artificialintelligence –Fuzzylogicinterpretspatientcondition –Rulebasedexpertsystemtreatscondition Operatorsets –patientweight –history(neuroorCOPD) –typeofairway 51

52. CharacteristicsofaMode 1.BreathingPattern –Controlvariable –Breathsequence 2.ControlType –Setpoint,auto-setpoint,servo,adaptive,optimal knowledgebased 3.SpecificControlStrategy –Phasevariables –Operationallogic 52

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

54. ModeDescriptionSummary (withoutthebrandjargon) •PressureSupport –OnlyLevel1needed PC-CSV •VolumeSupport –RequiresLevel2 PC-CSVwithadaptivecontrol 54

55. AdaptivePressureControl • • • • PressureRegulatedVolumeControl AutoFlow VC+ PC-SIMV+VolumeGuarantee 55

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

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

58. TooComplicated? 58

59. FinalThought “Ifyouexplainsomethingso simplythatevenafoolcan understandit,thenonlya foolwillunderstandit." FPPrimianoJr 59