ventilation presentation final

8/3/2019 Ventilation Presentation FINAL

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Basic Modes Of MechanicalVentilation

Ahmed Rezk Ahmed


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DefinitionsDefinitions

PIPPIP:: Peak Inspiratory PressurePeak Inspiratory Pressure

PEEPPEEP:: Positive End Expiratory PressurePositive End Expiratory Pressure

Rate(Rate((f) : Set Respiratory Rate By Machine: Set Respiratory Rate By Machine

Pressure SupportPressure Support: amount: amount of pressure applied to the airwayof pressure applied to the airwayduring spontaneous inspirationduring spontaneous inspiration

TV:TV: volume set to be delivered by machinevolume set to be delivered by machine

II--timetime:: amount of time delegated to inspirationamount of time delegated to inspiration..

FiOFiO22:: Fractional concentration of inspired oxygen delivered Flow: velocity of gas flow or volume of gas per minute

Trigger: Machine Sensor That Detects Pt Effort


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Vent settings to improve Vent settings to improve

FIO2 Simplest maneuver to quickly increase PaO2 Long-term toxicity at >60%

Free radical damage

Inadequate oxygenation despite 100% FiO2usually due to pulmonary shunting

Collapse Atelectasis

Pus-filled alveoli Pneumonia

Water/Protein ARDS

Water CHF

Blood - Hemorrhage

PEEP and FiO2 are adjusted in tandem


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PEEP Increases FRC

Prevents progressive atelectasis andintrapulmonary shunting

Prevents repetitive opening/closing (injury)

Recruits collapsed alveoli and improvesV/Q matching

Resolves intrapulmonary shunting

Improves compliance

Enables maintenance of adequate PaO2at a safe FiO2 level

Disadvantages

Increases intrathoracic pressure (mayrequire pulmonary a. catheter)

May lead to ARDS

Rupture: PTX, pulmonary edema

PEEP ,PIP and FiO2 are adjusted in tandem

Oxygen delivery (DO2), not PaO2, should beused to assess optimal PEEP.


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Respiratory rate Max RR at 35 breaths/min

Efficiency of ventilation decreaseswith increasing RR

Decreased time for alveolar emptying

TV Goal of 10 ml/kg

Risk of volutrauma

Other means to decrease PaCO2 Reduce muscular activity/seizures

Minimizing exogenous carb load

Controlling hypermetabolic states

Permissive hypercapnea

Preferable to dangerously high RRand TV, as long as pH > 7.15

RR and TVare adjusted to maintain VE and PaCO2

I:E ratio (IRV) Increasing inspiration time will

increase TV, but may lead toauto-PEEP

PIP

Elevated PIP suggests need forswitch from volume-cycled topressure-cycled mode

Maintained at


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Modes Of Mechanical

Ventilation


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Classifying Modes

of VentilationA. Start Trigger mechanism:

What starts the breath?

B. Limits What is controlled

and what is variable?

C. End

Cycle mechanism:What causes the

breath to end?

A

B C


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Volume control ventilator

V

P

V


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Volume vs. PressureVolume vs. Pressure


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If compliance decreases the pressure increases to

maintain the same Vt

Volume Control Breath TypesVolume Control Breath Types

11 22 33 44 55 66

SECSEC

11 22 33 44 55 66

PPawawcmHcmH2200

6060

--2020

120120

120120

SECSEC

INSPINSP

EXHEXH

FlowFlowL/minL/min


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Volume Control Breath TypesVolume Control Breath Types


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Pressure Mode

Pressure

Flow

Vo

lume

Time


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V

P

V

Pressure control ventilator


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Pressure vs. Volume

Pressure Limited Control FiO2 and

MAP (oxygenation)

Still can influenceventilationsomewhat(respiratory rate,PAP)

Decelerating flowpattern (lower PIPfor same TV)

Volume Limited Control minute

ventilation

Still can influenceoxygenationsomewhat (FiO2,PEEP, I-time)

Square wave flowpattern


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Pressure vs. Volume

Pressure TV change suddenly as

compliance changes

Lead to hypoventilationor overexpansion of lung

if ETT obstructed ,delivered TV decrease

Volume no limit PIP ally vent

will have upper

pressure limit alarm) square wave(constant)

flow pattern results inhigher PIP for same

tidal volume ascompared to Pressuremodes


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BasicModesOfMechanical

Ventilation

CMV

Assist/Control

IMV/SIMV

PSV

CPAP


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Control Modes


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Controlled Mandatory

Ventilation

CMV The ventilator

delivers a setpressure limit(ORvolume limit) over

a set inspiratorytime and patient

not allowed to

breath inbetween

F

P


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Ventilation

CMV


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Initial settings

Type - Pressure control

(VOLUME control)

Mode CMV

TI

RateFiO

PIP (TV)

PEEPPS

Trigger


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Modes ofmechanical ventilation

Time

Pressure

PIP


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Ventilation

CMV


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Ventilation

CMV

Advantages

Limits risk of barotrauma May recruit collapsed alveoli

Improved gas distribution

ll d d


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Ventilation

CMV Disadvantages

TV vary when compliancechanges (i.e. ARDS, pulmonary

edema)

NO synchronization Require sedation and paralysis


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Assist Control

Patient is able totrigger the start

of inspiration

F

P


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Initial settings


Volume control

Mode A/C

TI

RateFiO

PIP(TV)

PEEPPS

Trigger


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Time

Pressure

Assisted Controlled



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Assist ControlPt. always receives a mechanical breath, either

timed or assisted


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Assist Control

Safety issues

Control rate must be set enough toinsure that minute ventilation will beadequate

As rate increases expiratory time willshorten and gas trapping may occur (RRAlarm Limit Must Be Set)


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Assist Control

Indications

When full ventilatory support is needed

When pt. has a stable respiratory drive Some units especially ADULT ICU use it

as intial and maintaining mode

ARDS network recommended it as initialprotocol


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Assist Control

Advantages

Very small WOB when trigger and

flow are set properly Allows pt. to control RR

Better synchrony


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Assist Control

Disadvantages:

- Can potentially induce respiratoryalkalosis if high respiratory drive

- Asynchrony &respiratory musclefatigue

-I:E ratio can vary due to variable RR

can alter the expiratory phase.- High RR can induce lung injury


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Intermittent Mandatory

Ventilation

(IMV)

Ventilator lets patient breathe spontaneously BUT

does not change its plan of ventilation.


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Synchronize Intermittent

Mandatory Ventilation

SIMV

Minimum mandatory

breath rate is set withspontaneous breathingbetween mandatorycycles

F

P


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Initial settings


Vo;ume control

Mode SIMV

TI

Rate

FiO

PIP(TV)PEEP 5

PSTrigger


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Pressure

Flow

Volume

(L/min)

(cm H2O)

(ml)

Set P level

Time (sec)

spont

CPAP level


SIMV



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SIMV Hybrid between IMV and AC.

Three kinds of breaths:

SpontaneousAssisted

Mandatory



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SIMVIf machine senses that patient hastaken a spontaneous breath just

before mandatory breath themachine will recycle, then wait fornext spontaneous breath and

assist it.



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SIMVIf no breaths are initiated within aperiod of time, a mandatory

breath will be deliveredventilator assisted breaths are

synchronized with patients'

breathing to prevent possibility ofmechanical breath on top of

spontaneous breath



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SIMV Synchronized window

refers to time just prior to time

triggering in which the vent. isresponsive to the pt.s effort (0.3-0.5 sec is typical)


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SIMV

SIMV divides Tb into Mandatoryperiods (Tm) and Spontaneous

periods (Ts)


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SIMV

If patient tries to breathe duringTm, the ventilator gives a FULLY

ASSISTED BREATH


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SIMV

If patient tries to breathe during Ts, ventilatorallows the patient to take the breath.



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SIMV Advantages

Synchronized breaths improve

patient comfort Increase control/regulation

Enhances blood flow Hyperventilation less than A/C



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SIMV Advantages

reduces V/Q mismatch

Decreases mean airway press Maintaining resp. muscle strength



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SIMV Disadvantages:

It has been shown to be the least

beneficial weaning mode. Cannot fully control the I:E ratio

given the variability in RR and

presence of spontaneous breaths.


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Pressure

Flow

Volume

(L/min)

(cm H2O)

(ml)

Set P level

Time (sec)

SIMV + PS + CPAPPressure control ventilation

SIMV + PS + CPAPPressure control ventilation

Set Ps level

CPAP level


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Control vs. SIMV

Control Modes Every breath is supported

regardless of trigger

Cant wean by decreasingrate

Patient mayhyperventilate if agitated

Patient / vent asynchrony

possible and may needsedation +/- paralysis

SIMV Modes

Vent tries to synchronize

with pts effort

Patient takes ownbreaths in between (+/- PS)

Potential increased work of

breathing

Can have patient / ventasynchrony


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Spontaneous modes


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Spontaneous Breaths. Mechanical Breaths.

Time

volume

Pressure

FLOW


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Pressure Support Ventilation

PSVentilator delivers a

set pressure limit

ith end inspirationdriven by patient

(flow cycled)F

P


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Initial settings


Mode PS

TI

Rate

FiO

PIP

PEEP 5Trigger


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Initial settings


Mode PS

TI

Rate

FiO

PIP

PEEP 5PS

PSV

PSV


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PSVPSV

Time (sec)

Flow(L/m)

Pressure

(cm H2O)

Volume(mL)

Flow CyclingFlow Cycling

Set PS levelSet PS level


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Peak Pressure dependssolely upon the amount

of Pressure Support


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PSV

Safety issues

Patient must be able to triggerventilator & volumes are appropriate

High or low rate, apnea, high or low

tidal volume alarms need to be assessed


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PSVUsesPSV alone

for recovering intubated pts who are not

quite ready for extubation.Augments inflation volumes during

spontaneous breaths

Combined With Other modes (SIMV,..etc)


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PSV

Uses

As a weaning mode

In Non Invasive Ventilation

Some centers uses it as the mainconventional mode


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PSV

What is the right amount of pressure support?

No formula to calculate right amount.

Sometimes it can be estimated from RESISTANCE

Right level of PS is at which patient is comfortable & receiving

adequate ventilation.

Comfort can be assessed from the RR (


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PSV

What is the right amount of pressure support?

Higher levels are usually necessary when the compliance is low

(as in ARDS), airway resistance is high (as in COPD or asthma) or

the patient is with only weak inspiratory efforts.

A useful starting level is 10-15 cm H2O.

Adjustments should be made quickly with in minutes afterassessing patient comfort and adequacy of ventilation.


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PSV

Disadvantages:

Depends mainlyon patient effort so if

apnea occurs backup ventilation willoccur


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PSV

Disadvantages:

Inadequate volumes could be delivered

if the ETT is blocked or decreased lungcompliance causes present pressure limit

to stop inspiratory flow before an

adequate Vt is delivered (e.g.,pneumothorax).


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PSV

Disadvantages:

If Inspiratory off-switch failure, that is,

application of inspiratory pressure aftercessation of inspiratory muscle activity, iscommon during PSV.


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PSV

Disadvantages:

patient-ventilator asynchrony.

High inspiratory pressure settings

Low respiratory drive

Airflow obstruction with dynamic

hyperinflation Air leaks


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How to set Ti in a spontaneous breathing patient on

a pressure support mode ?

Flow

Pressure

Tinsp.PIP

PeakFlow

25%

Pressure Control Pressure Support

Flow termination criteria

Pressure-Support and flow termination criteria


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The non synchronized patient during Pressure-Support(inappropriate end-inspiratory flow termination criteria)

Nilsestuen J Respir Care 2005;50:202232.

Pressure-Support and flow termination criteria


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PEEP

Definition Positive end expiratory pressure

Application of a constant, positive pressure such that

at end exhalation, airway pressure does not return to

a 0 baseline

Used with other mechanical ventilation modes such as

A/C, SIMV, or PCV

Referred to as CPAP when applied to spontaneous

breaths


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PEEP

Increases functional residual capacity (FRC)and improves oxygenation

Recruits collapsed alveoli

Splints and distends patent alveoli

Redistributes lung fluid from alveoli toperivascular space

55 cmcm

HH22OO

PEEPPEEP


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Continuous Positive Airway

Pressure

(CPAP):

Elevation of end-expiratory pressure to levels

above atmospheric pressure to increase totallung volume

Increase functional residual capacity, thus

favoring improved oxygenation


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Pressure

(CPAP):

No mechanical inspiratory assistance is

provided Requires active spontaneous respiratory drive


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Initial settings


Mode - CPAP

TI

Rate

FiO

PIP

PEEP 5Trigger



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y

Pressure

(CPAP) May decrease WOB

Tidal volume and rate determined by patient

Often final form of support before extubation

55 cmcm

HH22OO

PEEPPEEP

TimeTime



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y

Pressure

(CPAP)


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Pressure

(CPAP)Indications:

- recurrent apnea, not from CNS origin,- ASSOCIATED exhaustion & muscle fatigue


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Pressure

(CPAP)Indications:

- Syndrome of premature baby (RDS)- TTN

- Mild Pulmonary edema

- Mild to severe pneumonia .


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Pressure

(CPAP)Indications:

- Weaning- When reduction of intubation is desired

- Some centers consider it as a NIV mode


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Pressure

(CPAP) Advantages :

increased lung volume and FRC improve in ventilation/perfusion ratio

preventing and resolving atelectasis


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Pressure

(CPAP)Advantages:

Reduced WOB

Prevention of muscle fatigue Normalization of respiratory frequency


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Pressure

(CPAP)Disadvantage

- decrease the venous return and lymph flow

- Risk of barotrauma

- not applicable in severly compromisedpatients

But what if my patient wants


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Pressure SupportCPAP

PS/CPAP

But what if my patient wants

to breathe on his/her own?

Positive pressure maintained in the ventilator circuitduring the inspiratory phase

Inspiratory limb

Expiratory limb

To patient


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Trigger

How does the vent know when to give abreath? - Trigger

patient effort

elapsed time

The patients effort can be sensed as a

change in pressure or a change in flow(in the circuit)


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Trigger

Time (IMV)

Pressure

Flow

Chest impedance

Abdominal movement

ELECTRIC DIPHRADMATIC ACTIVITYnew


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Trigger

Flow patient achieves set flow

Pressure patient achieves setnegative pressure

WHAT Is The Ideal


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WHAT Is The Ideal

MODE??????????!!!!!!!!

d l d f til ti


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Ideal Mode of Ventilation

Delivers a breath that:

Synchronizes with patients spontaneousrespiratory effort

Maintains adequate& constant TV & minuteventilation at low MAP

Responds to rapid changes in pulmonary

mechanics or patient demand Provides the lowest possible WOB


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ventilation presentation final

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