basic modes of mechanical ventilation -
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MODES OF MECHANICAL VENTILATION
Mazen Kherallah, MD, FCCP
POINTS OF DISCUSSIONS
Advanced Basics:Flow and TimeLimit and cyclingRise TimeVolume vs Pressure Control
Mandatory Modes of VentilationControlled Mandatory Ventilation (CMV or IPPV)
Triggered Modes of VentilationContinuous Positive Airway Pressure (CPAP) Pressure Support Ventilation (PSV)
Hybrid Modes of VentilationAssist Control Mode (A/C)Synchronized Intermittent Mandatory Ventilation (SIMV)
ADVANCED BASICS
RESPIRATORY CYCLE
Inspiration
Expiration
ExpInsp
RELATIONSHIP BETWEEN TIDAL VOLUME, INSPIRATORY TIME AND FLOW
VT 1
Ti a
VT 2
VT 3
Time
Volume
Flow= 30 L/min
Flow= 15 L/min
Flow= 37.5 L/min
ExpExpInspInspInsp
RELATIONSHIP BETWEEN TIDAL VOLUME, INSPIRATORY TIME AND FLOW
VT 1
Ti a
Time
Volume
Ti b Ti c
Flow= 30 L/min
Flow= 20 L/min
Flow= 60 L/min
PRESSURE LIMITED BREATH
Time
Volume
Pressure Limit
EXPIRATORY FLOW CYCLING
Time
Flow
50%
100%
Flow Cycling
RISE TIME
Time
Flow
Pressure
Volume
TI TE
MANDATORY, SPONTANEOUS AND TRIGGEREDINSPIRATORY CYCLING
M
S
Tsynch
M M
M
MM
M
M
S
M
Tsupp Tsupp
Tsupp Tsupp
Tsupp
Tsupp
S
VOLUME CONTROLLED INFLATION
Time
Flow
Pressure
Volume
TI TE
Tidal Volume
If compliance decreases the pressure increases to maintain the same Vt
1 2 3 4 5 6
SEC
1 2 3 4 5 6
PawcmH20
50
-20
120
120
SEC
INSP
EXH
FlowL/min
VOLUME CONTROL BREATHS
Decreased Compliance
VOLUME CONTROL WITH END-INSPIRATORYPAUSE
Time
Flow
Pressure
Volume
TI TE
Tidal Volume
End Inspiratory Pause
PRESSURE CONTROLLED INFLATION
Time
Flow
Pressure
Volume
TI TE
Tidal Volume
Rise Time
Peak Inspiratory Flow
Inspiration Expiration
0 120
00 1 2
3
-3
0
20
0 21
20
00 1 2
3
-3
0
20
0 2
Inspiration Expiration
Volume/Flow Control Pressure Control
Time (s) Time (s)
PawPaw
Pressure
Volume
Flow
TRIGGERED MODES OFVENTILATIONCPAP and PSVV
SPONTANEOUS BREATHING
Time (sec)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
CONTINUOUS POSITIVE AIRWAY PRESSURE(CPAP)
Time (sec)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
CPAP Level
PRESSURE SUPPORT VENTILATION(PSV)
Time (sec)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Set PS Level
Flow Cycling
Better Efforts
Longer Inspiration
Patient Triggered, Flow Cycled, Pressure limited Mode
CPAP+PSV
Time (sec)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Set PS Level
Flow Cycling
Patient Triggered, Flow Cycled, Pressure limited Mode
CPAP Level
TRIGGERED MODES OF VENTILATIONPRESSURE SUPPORT VENTILATION
Control Trigger Limit Target Cycle
Pressure Patient Pressure Flow
Patient Triggered Flow Cycled Ventilation
PRESSURE OR VOLUME-TARGETEDVENTILATION
Full to partial ventilatory supportAugments the patients spontaneous VTDecreases the patient’s spontaneous respiratory rateDecreases patient WOB by overcoming the resistance of the artificial airway, vent circuit and demand valvesAllows patient control of TI, Vm I, f and VTSet peak pressurePrevents respiratory muscle atrophyFacilitates weaningImproves patient comfort and reduces need for sedationMay be applied in any mode that allows spontaneous breathing, e.g., VC-SIMV, PC-SIMV
Requires consistent spontaneous ventilationPatients in stand-alone mode should have back-up ventilationVT variable and dependant on lung characteristics and synchronyLow exhaled VE
Fatigue and tachypnea if PS level is set too low
Advantages Disadvantages
MANDATORY MODES OFVENTILATIONCMV or IPPV
MANDATORY MODES OF VENTILATIONCMV
Control Trigger Limit Target Cycle
PressureOr
Volume
Time Time
Time Triggered Time Cycled Ventilation
CONTROL MODE(PRESSURE-TARGETED VENTILATION)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Time Triggered, Pressure Limited, Time Cycled Ventilation Time (sec)
Time CyclingSet PC Level
CONTROL MODE(VOLUME-TARGETED VENTILATION)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Time Triggered, Flow Limited, Volume Cycled Ventilation Time (sec)
Preset VTVolume Cycling
Time Cycling
Dependent onCL & Raw
PRESSURE OR VOLUME-TARGETEDVENTILATION
Decreases the work of breathing (WOB)Helps maintain a normal PaCO2
Not able to assist the ventilator
Advantages Disadvantages
HYBRID MODES OFVENTILATIONSIMV and A/C
HYBRID MODES OF VENTILATIONA/C
Control Trigger Limit Target Cycle
PressureOr
Volume
Time Or
Patient
Time
Time or PatientTriggered Time Cycled Ventilation
ASSISTED MODE(VOLUME-TARGETED VENTILATION)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Patient Triggered, Flow limited, Volume Cycled Ventilation Time (sec)
Preset peak Flow
Time Cycling
ASSISTED MODE(PRESSURE-TARGETED VENTILATION)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Patient Triggered, Pressure Limited, Time Cycled Ventilation Time (sec)
Time CyclingSet PC Level
PRESSURE OR VOLUME-TARGETEDVENTILATION
Decreases the work of breathing (WOB)Allows patients to regulate respiratory rateHelps maintain a normal PaCO2
Alveolar hyperventilation
Advantages Disadvantages
HYBRID MODES OF VENTILATIONSIMV/PS
Breath Type
Control Trigger Limit Cycle
Mandatory PressureOr
Volume
Time Or
Patient
Time
Spontaneous Pressure Patient Pressure Flow
SIMV(VOLUME TARGETED VENTILATION)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Spontaneous Breaths
M M M
Time (sec)
SIMV+PS(VOLUME TARGETED VENTILATION)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
MTsuppTsynch
Set PS Level
Flow-cycled
Time (sec)
SIMV + PS (PRESSURE-TARGETED VENTILATION)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Tsupp
Tsynch
Time CycledFlow-cycled
Tsynch
Set PC Level Set PS Level
Time (sec)
HYBRID MODE VENTILATION: SUPPRESSION
Time (sec)
Flow
(L/m
)Pr
essu
re(c
m H
2O)
Cyc
les
M Tsupp MM Tsupp
M M
Tsupp Tsupp
HYBRID MODE VENTILATION: SYNCHRONIZATION(SIMV+PSV)
Time (sec)
Flow(L/m)
Pressure(cm H2O)
Cycles
Triggered window for supported breaths
Triggered window for synchronized breaths
Mandatory Cycle Time
M Tsupp Tsynch M Tsynch Tsupp
SIMV
Maintains respiratory muscle strength by avoiding muscle atrophyDecreases mean airway pressureFacilitates ventilator discontinuation –“weaning”!
When used for weaning, may be done too quickly and cause muscle fatigueMechanical rate and spontaneous rate may asynchronous causing “stacking”
May cause barotrauma or volutrauma
Advantages Disadvantages
ALL MODES TABLES
Mandatory Modes of VentilationsMandatory breaths
Inspiratory cycling Time Time Time Time
Control Volume Volume Volume (Pressure)
Target/Limit - Pressure-limited Volume-targeted
Feeadback - - Intra-breath Inter-breathExpiratory cycling Time Time Time TimeTriggered BreathsTypes None None None None
Supported Breaths
Control - - - -Target - - - -Feedback - - - -Expiratory Cycling - - - -Spontaneous Breaths
During mandatory inspiration Not accommodated
Not accommodated
Not accommodated Accommodated
Otherwise Not accommodated Accommodated Not
accommodated Accommodated
Synonyms
IPPV (Draeger)Controlled Mandatory Ventilation
Intermittent Mandatory Ventilation
IPPV (Draeger): trigger off, autoflow off
IPPV (Draeger): trigger off,autoflow on
Triggered Modes of Ventilations
Mandatory breaths
Inspiratory cycling - - -
Control - - -
Target/Limit - - -
Feeadback - - -
Expiratory cycling - - -
Triggered Breaths
Types Supported breaths Supported breaths Supported breaths
Supported Breaths
Control Pressure (Pressure) (Pressure)
Target -- Volume-targeted Flow and Volume
Feedback -- Inter-breath Intra-breath
Expiratory Cycling Flow Flow Flow
Spontaneous Breaths
During mandatory inspiration - - -
Otherwise - - -
Synonyms
Assisted Spontaneus Breathing (Draeger)Spontaneous Mode (Hamilton, Puritan Bennet)Pressure Support (MaquetPressure Support Ventilation (Viasys)CPAP (Respironics)
Volume Support (Maquet, Puritan-Bennett)
Propotional Assist Ventilation, Proportional Pressure Suport (Draeger)Propotional Assist Ventilation Plus (Puritan-Bennet)
Hybrid Mode: Assist Control
Mandatory breaths
Inspiratory cycling Time or trigger Time or trigger Time or trigger
Control Volume Pressure (Pressure)
Target/Limit - - Volume-targeted
Feeadback - - Inter-breath
Expiratory cycling Time Time Time
Triggered Breaths
Types Mandatory pattern Mandatory pattern Mandatory pattern
Supported Breaths
Control - - -
Target - - -
Feedback - - -
Expiratory Cycling - - -
Spontaneous Breaths
During mandatory inspiration Not accommodated Accommodated Accommodated
Otherwise - - -
Synonyms
IPPVASSIST (Draeger)Synchronized cCntrolledMandatory Ventilation (Hamilton)Volume Control (Maquet)VCV-A/C (Puritan-Bennett, Respironics)Volume A/C (Viasys)
BIPAPASSIST (Draeger)P-CMV (Hamilton)Pressure Control (Maquet)PCV-A/C (Puritan-Bennett, Respironics)Pressure A/C (Viasys)
Adaptive Pressure Ventilation CMVPRVC (Maquet)VC+A/C (Puritan-Bennet)PRVC A/C (Viasys)IPPV Assist Autoflow(Draeger)
Hybrid Mode: Synchronized Intermittent Mandatory Ventilation
Mandatory breaths
Inspiratory cycling Time or trigger Time or trigger Time or trigger
Control Volume Pressure (Pressure)
Target/Limit - - Volume-targeted
Feeadback - - Inter-breath
Expiratory cycling Time Time Time
Triggered Breaths
Types Mandatory and supported pattern
Mandatory and supported pattern
Mandatory and supported pattern
Supported Breaths
Control Pressure Pressure Pressure
Target - - -
Feedback - - -
Expiratory Cycling Flow Flow Flow
Spontaneous Breaths
During mandatory inspiration Not accommodated Accommodated Accommodated
Otherwise Only if support is off Only if support is off Only if support is off
Synonyms
SIMV (Draeger, Hamilton)SIMV (VC)+PS (Maquet)VCV-SIMV (Puritan-Bennett, Respironics)Volume SIMV (Viasys)
P-SIMV (Hamilton)SIMV(PC)+PS (Maquet)PCV-SIMV (Puritan-Bennett, Respironics)Pressure SIMV (Viasys)
SIMV+AutoflowAdaptive Pressure Ventilation SIMV (Hamilton)SIMV (PRVC)+PS (Puritan-Bennett)PRVC SIMV (Viasys)
Hybrid Mode: Bi-Level Ventilatio
Mandatory breaths
Inspiratory cycling Time or trigger Time or trigger Time or trigger Time or trigger
Control Pressure Pressure Pressure Pressure
Target/Limit - - - -
Feeadback - - - -
Expiratory cycling Time or trigger Time or trigger Time or trigger Time or trigger
Triggered Breaths
Interaction Mandatory and supported
Mandatory pattern and supported
Mandatory and supported
Mandatory and supported
Supported Breaths
Control Pressure Pressure Pressure Pressure
Target - - - -
Feedback - - - -
Expiratory Cycling Flow Flow Flow Flow
Spontaneous Breaths
During mandatory inspiration Accommodated
Trigers suuport to PEEP+Psupport If this>Phigh (Hamilton DuoPAP)Plow+Psupport If this>Phigh (Hamilton APRV)PEEPL+PsuppIf this>PEEPH (Puritan-Bennett)
Triggers support to PRES HIGH + PSV if Thigh PSV is activated
Tigger support to PSV above PHigh
Otherwise Triggers support
Triggers support to PEEP+Psupport(Hamilton) DuoPAP)Plow+Psupport (Hamilton APRV)PEEPL+Psupp (Puritan-Bennett)
Triggers support to PREDSLOW=PSV
Triggers support to PSV above PEEP
Synonyms BIPAP (Draeger)
DuoPAP/APRV (Hamilton)BiLevel (Puritan-Bennet)
APRV/Bi-phasic(Viasys) Bi-vent (Maquet)
THANK YOU
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