Modes of Ventilation - NRRCC 2007.pdf

7/27/2019 Modes of Ventilation - NRRCC 2007.pdf

1/59

1

Mechanical VentilationMechanical VentilationUnderstanding ModesUnderstanding Modes

Rob Chatburn, RRTRob Chatburn, RRT--NPS, FAARCNPS, FAARC

Research ManagerResearch Manager Respiratory TherapyRespiratory Therapy

Cleveland ClinicCleveland Clinic

Associate ProfessorAssociate Professor

Case Western Reserve UniversityCase Western Reserve University


2/59

2

OverviewOverview

Characteristics of modes Pressure control vs volume control

Graphical representations of modes Breath types

Mandatory vs spontanous

Assisted vs unassisted

Breathing patterns Definitions, indications, examples

Graphical representations

Computer control of mechanicalventilation


3/59

3

Characteristics of a ModeCharacteristics of a Mode

1. Breathing Pattern Control variable

Breath sequence

2. Control Type Setpoint, auto-setpoint, servo, adaptive, optimal

3. Control Strategy

Phase variables

Operational logic


4/59

4

Control VariablesControl Variables

Ventilator can control only one variable at a timeIndependent variable is control variable

Pvent = E x V + R x V


5/59

5

Volume ControlVolume Control

Tidal volume and flow presetAirway pressure changes with lung

mechanics

Advantage:

Minute ventilation and gas exchange stable

Disadvantage:

Volume and flow may not be optimal


6/59

6

Pressure ControlPressure ControlAirway pressure preset

Volume and flow change with lungmechanics

Advantage: Better patient flow synchrony

Possibly better oxygenation

Potentially reduced risk of volutrauma

Disadvantage:

Gas exchange may not be stable


7/59

7

VolumeVolume

ControlControlInfluenceInfluence

DiagramDiagram

MinuteVolume

TidalVolume Rate

CycleTime

Inspiratory

Time

Expiratory

Time

I:E

Inspiratory

Flow


8/59

8

PressurePressure

ControlControlInfluenceInfluence

DiagramDiagram

MinuteVentilation

VentilatoryFrequency

TidalVolume

InspiratoryTime

ExpiratoryTime

I:E Ratio

PressureGradient

PeakInspiratoryPressure

EndExpiratoryPressure

Resistance

TimeConstant

Compliance

Mean

AirwayPressure

ContinuousFlow Rate

(Affects shapeof pressurewaveform)


9/59

9

0 Time (s)

Inspiration Expiration

Volume/Flow ControlVolume/Flow Control

0 Time (s)Flow

Pressure Paw

Volume Plung

Paw

Inspiration Expiration

Pressure ControlPressure Control


10/59

10

Dual ControlDual Control Volume control to Pressure Control:

Attempts to deliver a constant tidal volume whilelimiting peak pressure

Pressure control to Volume Control:

Attempts to limit peak pressure but assures tidalvolume delivery

Disadvantage:

Requires high degree of understanding

Difficult to adjust and maintain


11/59

11


1. Breathing Pattern Control variable

Breath sequence


3. Control Strategy

Phase variables

Operational logic


12/59

12

Breath TypesBreath Types

What is the difference between

mandatory and spontaneous breaths?


13/59

13

Spontaneous

yes

no

Breath TypesBreath Types

Patient

controlssize

yes

Mandatory

no

Think

Patient

controlsstart


14/59

14

Definition of Assisted BreathDefinition of Assisted Breath

Assisted Ventilator does work on patient.

Un-Assisted

Ventilator does no work on patient. Loaded (work imposed on patient)

Patient does work on ventilator.


15/59

15

Identification of Assisted BreathsIdentification of Assisted Breaths

Assisted

Airway pressure rises above baseline duringinspiration (or falls below baseline duringexpiration).

Un-Assisted Airway pressure stays constant during inspiration

or expiration.

Loaded (work imposed on patient) Airway pressure falls below baseline during

inspiration and rises above baseline duringexpiration.


16/59

16

Assisted Spontaneous BreathsAssisted Spontaneous Breaths

Pressure Support Volume Support

Automatic Tube Compensation Proportional Assist Ventilation

SmartCare


17/59

17

Potential ConfusionPotential Confusion

An assisted breath may bespontaneous or mandatory

A spontaneous breath may beassisted or unassisted

A mandatory breath is assisted by

definition


18/59

18


1. Breathing Pattern

Control variable

Breath sequence


3. Control Strategy

Phase variables

Operational logic


19/59

19

Continuous MandatoryContinuous Mandatory

Ventilation (CMV)Ventilation (CMV)

Mandatory breaths Machine triggered and/or machine cycled

Spontaneous breaths

During mandatory breaths only, not between

Key clinical concept

Level of support independent of frequency (ifpatient is breathing)


20/59

20

Intermittent MandatoryIntermittent Mandatory

Ventilation (IMV)Ventilation (IMV)

Mandatory breaths Machine triggered and/or machine cycled

Spontaneous breaths

Between and during mandatory breaths

Key clinical concept

Level of support is proportional to set frequency(if spontaneous breaths unassisted)

Historically used as a mode of weaning


21/59

21

Continuous SpontaneousContinuous Spontaneous

Ventilation (CSV)Ventilation (CSV)

All breaths spontaneous Patient triggered and cycled

No backup rate in case of apnea

Breaths may or may not be assisted

Full support may be achieved (if no apnea)


22/59

22


1. Breathing Pattern

Control variable

Breath sequence


3. Control Strategy

Phase variables

Operational logic


23/59

23

8 Basic Breathing Patterns8 Basic Breathing PatternsControl

Variable

Breath

Sequence Symbol

Continuous Mandatory Ventilation VC-CMV

Intermittent Mandatory Ventilation VC-IMV

Continuous Mandatory Ventilation PC-CMV

Intermittent Mandatory Ventilation PC-IMV

Continuous Spontaneous Ventilation PC-CSV

Continuous Mandatory Ventilation DC-CMV

Intermittent Mandatory Ventilation DC-IMV

Continuous Spontaneous Ventilation DC-CSV

Dual

Pressure

Volume


24/59

24

VCVC--CMVCMV

Often referred to as Assist/Control

Characteristics

VC results in more even distribution of ventilationamong lung units with equal resistance and unequalcompliance than PC

Selection of flow and sensitivity is critical

Indications Need for total ventilatory support

Need for precise regulation of blood gases

Example Precise regulation of PaCO2 in patients with traumatic

brain injury


25/59

25

VCVC--CMVCMV

waveformswaveforms

Ven

tilato

r

Pressu

re

Vo

lume

Flo

w

Mu

sc

le

Pressure small

inspiratory

effort

large

inspiratory

effort

no

inspiratory

effort

A B C

patient

triggered

machine

triggered

reducedpressure

indicates patient

effort throughoutinspiration

set tidal volume

setflow

VC IMV


26/59

26

VCVC--IMVIMV

Characteristics Spontaneous breaths may be assisted

Selection of mandatory flow and spontaneouspressure support critical

Indications Relatively normal lung function

Rapid recovery from sedation or respiratory failure

Recent data suggest it is worst choice for weaning

ExampleTreatment of neuromuscular disease like Gullian-Barre syndrome


27/59

27

VCVC--IMVIMV

waveformswaveforms

Ven

tilato

r

Pressur

e

Vo

lume

Flo

w

Mus

cle

Pres

sure small

inspiratory

effort

no

inspiratory

effort

A B C

patient

triggered

machine

triggered

medium

inspiratory

effort

setpressure support

settidal volume

setflow

Are spontaneous

breaths assisted?


28/59

28

PCPC--CMVCMV Characteristics

PC results in more even distribution of ventilationamong lung units with equal compliance and unequalresistance than VC

Pressure control results in higher mean airway

pressure and earlier lung opening than VC

Indications Problems with oxygenation or synchrony

Example Treatment of ARDS patients with oxygenation

problems


29/59

29

PCPC--CMVCMV

waveformswaveforms

Ven

tilat

or

Pressure

Vo

lume

Flo

w

Musc

le

Pres

sure small

inspiratory

effort

large

inspiratory

effort

no

inspiratory

effort

A B C

patient

triggered

machinetriggered

time cycled

setpressure limit


30/59

30

PCPC--IMVIMV Characteristics

Relatively simple mode Used historically for infants

Spontaneous breaths may be assisted

Indications Problems with oxygenation or synchrony

Adequate ventilatory drive

Example Treatment of premature infants with RDS


31/59

31

PCPC--IMVIMV

waveformswaveforms

Ven

tilato

r

Pressure

Vo

lume

Flo

w

Mus

cle

Pressure large

inspiratory

effort

no

inspiratory

effort

A CBmedium

inspiratory

effort


32/59

32

PCPC--CSVCSV

Characteristics No assist = CPAP

Assist Pressure Support

Proportional Assist

Automatic Tube Compensation

Indications Weaning

Reduce work of breathing or stabilize oxygenation Examples

Nasal CPAP for neonates recovering from RDS

Noninvasive ventilation of adults

A B C


33/59

33

PCPC--CSVCSV

waveformswaveforms

Spontaneous

breaths are not

assisted

(CPAP)

Ven

tila

tor

Pressu

re

Vo

lume

Flo

w

Mu

sc

le

Pre

ssure small

inspiratory

effort

large

inspiratory

effort

no

inspiratory

effort

A B C

DCDC CMVCMV


34/59

34

DCDC--CMVCMV

Characteristics

Mandatory breaths adapt to changing lungmechanics

Indications

Unstable lung mechanics or ventilatory drive

Example

Treatment of patient with pneumonia andintermittent secretion problems

A B


35/59

35

DCDC--CMVCMV

waveformswaveforms

Ven

tilato

r

Pressu

re

Vo

lume

Flo

w

Mu

sc

le

Pres

sure

large

inspiratory

effort

no

inspiratory

effort

A B

patient

triggered

pressure limit

over-ridden

set volume target volume cycled

flow cycledsetflow limit

setpressure limit

switch frompressure control

to volume control

volume target

not met

inspiratory flowequals flow limit

volume metbefore

flow decays to set limit

pressure-to-volume

Bird VAPS

A B


36/59

36

DCDC--CMVCMV

waveformswaveforms

volume-to-pressure

DrgerPressure Limited

VentilationV

en

tilato

r

Pressu

re

Vo

lume

Flo

w

Mu

sc

le

Pre

ssure small

inspiratory

effort

A B

set tidal volume

volume

limited

plateau

pressure

plateau

pressure

set Pmax

switch fromvolume control

to pressure control

volume limited

time cycledtime cycled


37/59

37

DCDC--IMVIMV

waveformswaveforms

Ven

tilato

r

Pressure

Vo

lume

Flo

w

Mus

cle

Pressure

A C

plateau

pressure

set Pmax

time cycled

set Pmax

time cycled

set tidal volume

setflow

B


38/59

38

Pressure SupportPressure Support

Pressure or flow triggered, pressurelimited, inspiratory flow cycled

Level of ventilatory support

determined by pressure limit

Sometimes set to approximately

support resistive work of breathing(through endotracheal tube)

A B C


39/59

39

PCPC--CSVCSV

waveformswaveforms

Spontaneous

breaths are

assistedV

en

tilat

or

Pressur

e

Vo

lume

Flo

w

Mus

cle

Pressure small

inspiratory

effort

large

inspiratory

effort

no

inspiratory

effort

A B C

patient

triggered

flow cycled

setpressure limit

flow cycle threshold

pressure rise

time

increased

P i l A iP ti l A i t


40/59

40

Proportional AssistProportional Assist

flowRvolumeEP normalnormalmus +=

( ) ( ) flowRRvolumeEEP abnormalnormalabnormalnormalmus +++=

( ) ( )loadabnormalloadnormalPmus +=

( ) ( )loadabnormalloadnormalPP ventmus +=+

flowRvolumeEloadabnormalP abnormalabnormalvent +==

operator settings (volume and flow amplification factors)

A B C


41/59

41

PCPC--CSVCSV

waveformswaveforms

Spontaneous breaths

are assisted

(Proportional Assist)V

en

tilat

or

Pressure

Vo

lume

Flo

w

Mus

cle

Pres

sure small

inspiratory

effort

large

inspiratory

effort

no

inspiratory

effort

A B C

A t ti T bA t ti T b


42/59

42

Automatic TubeAutomatic Tube

CompensationCompensation

2flowRloadresistiveabnormalP

tubevent

==

operator sets tube diameter

ventilator calculates resistance factor


43/59

43

Characteristics of a ModeCharacteristics of a Mode1. Breathing Pattern

Control variable

Breath sequence

2. Control Type Within breaths Between breaths

3. Specific Control Strategy Phase variables

Operational logic

Evolution of Ventilator Control TypesEvolution of Ventilator Control Types


44/59

44

ypyp

PatientVentilatorOperator

PatientVentilator

ModelOperator

PatientVentilator

Model

Strategic Control (between breaths)

adaptive (CMV+AutoFlow)

optimal (ASV)

ventilator-selected, dynamic setpoints

static model

Intelligent Control (between patients)

knowledge based

arti ficial neural network

ventilator-selected, dynamic setpoints

dynamic modelability to learn from experience

operator-selected, static setpoints

Tactical Control (within-breaths)

setpoint (PC-IMV)

auto-setpoint (Pmax)

servo (Automatic Tube Compensation)

T ti l C t lTactical Control


45/59

45

Tactical ControlTactical Control

All the modes discussed so far All require the operator to set

Pressure (PIP, PEEP) Volume (tidal volume, minute ventilation) Flow (peak inspiratory flow)Time (inspiratory time, frequency, I:E)

Strategic ControlStrategic Control


46/59

46

Strategic ControlStrategic Control

Characteristics Breathing pattern may be PC-CMV, PC-IMV, PC-CSV

Pressure limit automatically adjusted to compensate forchanges in compliance to meet target tidal volume

Indications (Self) Weaning

Reduce work of breathing or stabilize oxygenation Reduce clinician workload

Examples

Post-operative patients with normal lungs Mixed ICU patients COPD exacerbation

A B C


47/59

47

AdaptiveAdaptive

ControlControl

Ven

tilat

or

Pressure

Vo

lume

Flo

w

Musc

le

Pres

sure

large

inspiratory

effort

no

inspiratory

effort

patienttriggeredmachinetriggered

pressure limit

automatically reduced

volume targetvolume overshoot

time cycled

Hamilton Galileo Adaptive Support ModeHamilton Galileo Adaptive Support Mode


48/59

48

Hamilton Galileo Adaptive Support ModeHamilton Galileo Adaptive Support Mode

Optimum control Clinician enters

Patient ideal body weight Percent of predicted minute ventilation to support

Ventilator monitors

minute ventilation lung mechanics (expiratory time constant)

Automatically adjusts minute ventilation mandatory breath frequency

pressure limit inspiratory time

Sets frequency to minimize WOB as if

patient was breathing spontaneously


49/59

49

Any medicalinstrumentation that

requires constant

input from a human

operator is obsoleteHamilton Medical

Intelligent ControlIntelligent Control


50/59

50

Intelligent ControlIntelligent Control Characteristics

Classification of patient condition Manual (eg, by diagnosis)

Fuzzy logic Rule based expert system or artificial neural network

Indications

Weaning Respiratory failure of various typesTrauma

Examples Post-operative patients with normal lungs Mixed ICU patients Emergency department

C i l E lC i l E l


51/59

51

Commercial ExampleCommercial Example

SmartCare (Drger Evita XL) Knowledge Based Control

1. Automatically adjust pressure support: breathing rate, tidalvolume and end tidal CO2.2. Automatically test patient tolerance of a lower pressure

support level without leaving the comfort zone.3. Attempts extubation with PS at resistive WOB.

Artificial intelligence Fuzzy logic interprets patient condition Rule based expert system treats condition

Operator sets patient weight history (neuro or COPD) type of airway


52/59

52

Characteristics of a ModeCharacteristics of a Mode1. Breathing Pattern

Control variable

Breath sequence

2. Control Type Setpoint, auto-setpoint, servo, adaptive, optimalknowledge based

3. Specific Control Strategy Phase variables

Operational logic

Mode Description UtilityMode Description Utility


53/59

53

Mode Description UtilityMode Description Utility

Describe the difference in modes

Pressure Support

Volume Support

Describe the difference in ventilators

Pressure support (PB7200)

Pressure support (Servo-i)

Mode Description SummaryMode Description Summary


54/59

54

p yp y

(without the brand jargon)(without the brand jargon)

Pressure Support

Only Level 1 needed

PC-CSV

Volume Support Requires Level 2

PC-CSV with adaptive control


55/59

55

Adaptive Pressure ControlAdaptive Pressure Control Pressure Regulated Volume Control

AutoFlow

VC+

PC-SIMV + Volume Guarantee

Mode Description SummaryMode Description Summary


56/59

56

p y

(without the brand jargon)(without the brand jargon)

Level 3 Pressure Support

PB 7200 Cannot adjust rise time (limit variable)

Cannot adjust cycle threshold (cyclevariable)

Servo-i Adjustable rise time (limit variable)

Adjustable cycle threshold (cycle variable)


57/59

57

ResourcesResources Get the book

college level textbook

300 pages

www.aarc.org/store Training Software

www.VentWorld.com

www.Amazon.com


58/59

58

Too Complicated?Too Complicated?


59/59

59

Final ThoughtFinal Thought If you explain something so

simply that even a fool can

understand it, then only a

fool will understand it."

FP Primiano Jr

Modes of Ventilation - NRRCC 2007.pdf

Documents

Transcript of Modes of Ventilation - NRRCC 2007.pdf