Mechanical ventilation, understanding modes.

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Rob Chatburn, RRT RRT-NPS, FAARC
Research Manager – Respiratory Therapy
Cleveland Clinic
Associate Professor
Case Western Reserve University

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  • 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