Modes of Mechanical Ventilation
Feb 22, 2016
Modes of Mechanical Ventilation
POINTS OF DISCUSSIONS Advanced Basics:
Flow and Time Limit and cycling Rise Time Volume vs Pressure Control
Mandatory Modes of Ventilation Controlled Mandatory Ventilation (CMV or IPPV)
Triggered Modes of Ventilation Continuous Positive Airway Pressure (CPAP) Pressure Support Ventilation (PSV)
Hybrid Modes of Ventilation Assist Control Mode (A/C) Synchronized Intermittent Mandatory Ventilation (SIMV)
TRIGGERED MODES OF VENTILATION
CPAP 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 CyclePressure Patient Pressure Flow
Patient Triggered Flow Cycled Ventilation
MANDATORY MODES OF VENTILATION
CMV or IPPV
MANDATORY MODES OF VENTILATIONCMV
Control Trigger Limit Target CyclePressure
OrVolume
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 VT
Volume Cycling
Time Cycling
Dependent onCL & Raw
HYBRID MODES OF VENTILATION
SIMV and A/C
HYBRID MODES OF VENTILATIONA/C
Control Trigger Limit Target CyclePressure
OrVolume
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
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 Cycled Flow-cycled
Tsynch
Set PC Level Set PS
Level
Time (sec)
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 TsynchM Tsynch Tsupp
ADVANCED MODES OF MECHANICAL VENTILATION
POINTS OF DISCUSSION Triggered Modes of Ventilation
Volume Support (VS) Proportional Assist Ventilation (PAV or PPS)
Hybrid Modes of Ventilation Volume Assured Pressure Support Pressure Regulated Volume Control (PRVC) Auto mode: VS and PRVC Adaptive Support Ventilation: ASV Bi-level Ventilation (APRV and Bi-vent) Mandatory Minute Ventilation (MMV)
DUAL CONTROL BREATH-TO-BREATHPRESSURE-LIMITED FLOW-CYCLED VENTILATIONVOLUME SUPPORT
Control Trigger Limit Target CyclePressure Patient Pressure Volume Flow
Pressure Limited Flow Cycled Ventilation
VS (VOLUME SUPPORT)
(1), VS test breath (5 cm H2O); (2), pressure is increased slowly until target volume is achieved; (3), maximum available pressure is 5 cm H2O below upper pressure limit; (4), VT higher than set VT delivered results in lower pressure; (5), patient can trigger breath; (6) if
apnea alarm is detected, ventilator switches to PRVC
1 2 3 4 5 6
Pressure Upper Pressure limit
5 cm H2O
Flow
Apnea5 cm H2O
Constant exp. Flow
Volume fromVentilator=
Set tidal volume
Pressure limitBased on VT/C
Cycle off
Calculatecompliance
Calculate newPressure limit
no
yes
yes
no
Control logic for volume support mode of the servo 300
Trigger Flow= 5% ofPeak flow
DUAL CONTROL BREATH TO BREATH:PROPORTIONAL ASSIST VENTILATION(PAS)/PROPORTIONAL PRESSURE SUPPORT (PPS)
Control Trigger Limit Target CyclePressure Patient Pressure Volume Flow
Pressure Limited Flow Cycled Ventilation
PROPORTIONAL ASSIST VENTILATION (PAV)
Pressure
Flow
Time
Time
Rregulates the pressure output of the ventilator moment by moment in accord with the patient’s demands for flow and volume.Thus, when the patient wants more, (s)he gets more help; when less, (s)he gets less. The timing and power synchrony are therefore nearly optimal—at least in concept.
Changing pressure support based on patient’s efforts
PROPORTIONAL ASSIST AMPLIFIES MUSCULAR EFFORT
Muscular effort (Pmus) and airway pressure assistance (Paw) are better matched for Proportional Assist (PAV) than for Pressure Support (PSV).
DUAL CONTROL WITHIN A BREATHVOLUME-ASSURED PRESSURE SUPPORT
Control Trigger Limit Target CycleDual
Pressure/Volume
Patient Pressure Volume Flow or volume
Volume Assured Pressure Support Ventilation
PawcmH20
60
-20
60
FlowL/min
Volume
Set flow
Set tidal volume cycle threshold
Set pressure limit
Tidal volume met
Tidal volume not met
Switch from Pressure control toVolume/flow control
Inspiratory flowgreater than set flow
Flow cycleInspiratory flowequals set flow
Pressure limitoverridden
L
0
0.6
40
Pressure at Pressure support
delivered VT
≥ set VT
flow= 25% peak
Cycle offinspiration Insp flow
> Set flow
PAW <PSVsetting
delivered VT
= set VT
Switch to flow controlat peak flow setting
Trigger
yes
no
no
no
no
no
yes
yes
yes
Control logic for volume-assured pressure-support mode
yes
DUAL CONTROL BREATH-TO-BREATHPRESSURE REGULATED VOLUME CONTROL
Control Trigger Limit Target CycleVolume Patient or
TimePressure Lowest
pressurefor set volume
Time
Pressure-limited Time-cycled Ventilation
PRVC (PRESSURE REGULATED VOLUME CONTROL)
PRVC. (1), Test breath (5 cm H2O); (2) pressure is increased to deliver set volume; (3), maximum available pressure; (4), breath delivered at preset E, at preset f, and during preset TI; (5), when VT
corresponds to set value, pressure remains constant; (6), if preset volume increases, pressure decreases; the ventilator continually monitors and adapts to the patient’s needs
1 2 3 4 5 6
Upper Pressure Limit
5 cm H2OPressure
Floe
Time
Time
PRVC AUTOMATICALLY ADJUSTS TO COMPLIANCE CHANGESPressure control Ventilation PRVC
Volume fromVentilator=
Set tidal volume
Time= setInspiratory time
Pressure limitBased on VT/CTrigger Cycle off
Calculatecompliance
Calculate newPressure limit
no
yes
yes
no
Control logic for pressure-regulated volume control and autoflow
AUTOMODE
Mandatory SpontaneousPRVC VS
Ventilator triggered, pressure controlled and
time cycled; the pressure is adjusted to maintain the
set tidal volume
Patient triggered, pressure limited, and flow cycled.
Apnea for 12 seconds Two consecutive breaths
DUAL CONTROL BREATH-TO-BREATHADAPTIVE SUPPORT VENTILATION
ASV (ADAPTIVE SUPPORT VENTILATION) A dual control mode that uses pressure
ventilation (both PC and PSV) to maintain a set minimum E (volume target) using the least required settings for minimal WOB depending on the patient’s condition and effort It automatically adapts to patient demand by
increasing or decreasing support, depending on the patient’s elastic and resistive loads
ASV (ADAPTIVE SUPPORT VENTILATION) The clinician enters the patient’s IBW, which allows the
ventilator’s algorithm to choose a required E. The ventilator then delivers 100 mL/min/kg.
A series of test breaths measures the system C, resistance and auto-PEEP
If no spontaneous effort occurs, the ventilator determines the appropriate respiratory rate, VT, and pressure limit delivered for the mandatory breaths
I:E ratio and TI of the mandatory breaths are continually being “optimized” by the ventilator to prevent auto-PEEP
If the patient begins having spontaneous breaths, the number of mandatory breaths decrease and the ventilator switches to PS at the same pressure level
Pressure limits for both mandatory and spontaneous breaths are always being automatically adjusted to meet the E target
+
+TargetCurrent
MinVol 7.0 L/min
200
400
600
800
THE SAFETY WINDOW: LOW RATE/VOLUME LIMITS
VmL
10 20 30 40 50 60 fSpont0 b/min
fControl11 b/min
Pinsp18 cmH2O
fb/min
5 b/min
2 * Vd
(Pmax-PEEP)*Cdyn
f=60/[1RCinsp+2RCexp]
MANDATORY MINUTE VENTILATION A minimum minute ventilation is set by the
operator The ventilator monitors the spontaneous MV The part of the pre-selected MV that the
patient is not able to accomplish is provided by the ventilator to make up the difference by automatically changing the breath rate
MMV
time
Min.Vent.MMV
SMV
MMV SETTINGS
time
Min.Vent.
SMVMMV
MMV = 70-90% of SMV
BILEVEL VENTILATION
PEEPH
PEEPL
Pressure SupportPEEPHigh + PS
PawcmH20
60
-201 2 3 4 5 6 7
Thigh
Tlow
Plow
Phigh
Time
Time
Pre
ssur
eP
ress
ure
Psupp
Thigh
Tlow
Plow
Phigh
Time
Time
Pre
ssur
eP
ress
ure
Phigh
Psupp
Thigh
Tlow
Plow
Phigh
Time
Time
Pre
ssur
eP
ress
ure
PhighPsupp
Psupp
AIRWAY PRESSURE RELEASE VENTILATION
Control Trigger Limit CyclePressure Time Pressure Time
Time Triggered Time-cycled Ventilation
AIRWAY PRESSURE RELEASE VENTILATION
PawcmH20
60
-201 2 3 4 5 6 7 8
Spontaneous Breaths
Releases
APRV (AIRWAY PRESSURE RELEASE VENTILATION)
Spontaneous breaths
CPAP Level
CPAP Level 2CPAP Level 1
CPAP Released CPAP Restored
Time
Airw
ay P
ress
ure
QUESTIONS