vENTILATORGRAPHICS

IN PICU….. Optimizing

Ventilation

Dr Vishram BucheCentral India’s CHILD hospital & Research institute, NAGPUR

Part 1……..

OBJECTIVES……OBJECTIVES……

How to identify different WAVES and LOOPS ? and thereby mode of vent ?

How it helps to monitor Ventilator parameters ?

How it helps to adjust vent settings/ parameters ?

How it helps to manage disease pattern ?

How it helps to identify / quantify the problem?

GOAL …….

1. Reduce WOB, Optimize ventilation & Improve patient comfort 2. Maximize therapeutic effect 3. Minimize ventilator associated lung injury

Measured

FlowPressureTime

Calculated

VolumeComplianceResistanceWOBAuto-Peep

PARAMETERS…………

How it is measured….?

Pressure differential Pneumotachometer

Hot wire Anemometer

Where it is measured….?

At ETT

Inside ventilator

MEASUREMENT OF FLOW…….

MEASUREMENT OF PRESSURE ……….MEASUREMENT OF PRESSURE ……….

At ETT

In esophagus

Inside Ventilator

Where it is measured…. ?

Inside the Pt’s airway ……..???

A. Trigger …….What causes the breath to begin?

B. Limit ……….What regulates gas flow during the breath?

C. Cycle ……… What causes the breath to end?

D. Baseline…… End exp Pressure (FRC level)

Basic phase variables…………..

A

B C

DD

Pressure-time

Flow-time

Volume-time

Pressure- flow

Flow- volume Flow- pressure…???

Scalars……

Loops……...

The Pulmonary graphics display in two formats………

Basic shapes….. Square, Sine and Exponential rise or decay

Spontaneous Breaths…. Mechanical Breaths….

Time

volume

Pressure

FLOW

Volume ModesPressure Modes

Pre

ssur

eF

low

Vol

ume

Time

Volume ModesPressure Modes

Pre

ssur

eF

low

Vol

ume

Time

Breath type Triggering I:E ratio PIP/Plateau pressure MAP PEEP

Active exhalation Auto-PEEP Airway obstruction Bronchodilator response Compliance/Raw Asynchrony

Pressure waveform used to access…… Pressure waveform used to access……

Pressure mode volume mode

I:E ratio Breath type Inspiratory flow rate

(set/PIF) Rise time

Auto-PEEP Airway obstruction I-Time adjustment Active exhalation Bronchodilator response Asynchrony

Flow waveform used to access………

F

time

Time

Pressure mode Volume mode

Volume waveform used to access………

I:E Tidal volume Auto-PEEP Active exhalation Air-leak Airway resistance Asynchrony

Loops…….Loops…….

Pressure-Volume Loops

Flow-Volume Loops

Flow-pressure loops ???

inspiration

expiration

15 305

Volu

me

Pressure

PIPVolume

Inspiration

Expiration

Flow

PIFR

PEFR

FRC

VT

P-V loop F-V loop

Breath typeTidal volumePIPI & E flow rate

ResistanceComplianceAsynchrony

Air leakssecretions

Graphic analysis to optimize ventilation…..

Tidal volumes too low Inspiratory flow too slow Inspiratory time too long Trigger sensitivity too negative Increased resistance of ETT AutoPEEP Pain, discomfort and agitation

Common causes of Pt-vent asynchrony……………..

PIP

P plat

PIP

P plat

Pressure wave…………Effect of ed air way resistance/compliance

Effect of Auto-PEEP....

While performing an expiratory hold maneuver, trapped air will cause the waveform to rise above the baseline.

Air-trapping…..Auto-PEEP

Pressure wave…………

Tachypnoea ....earliest sign Appearance of s/o resp distress With present vent setting like Accessory muscles usage, intercostal retractions etc Rising PaCO2 is a late sign

Clinical signs of AUTOPEEP…………

I Rise time……. How do I adjust it?I Rise time……. How do I adjust it?

P

F

time

time

0

0

Too fast time

Bart simpson spike

Rise time “overshoots”Desired pressure

I Rise time…….fastI Rise time…….fast

“SPIKE ” on graphics IRT is set at 0.05 seconds

I Rise time…….fastI Rise time…….fast

Increase IRT…………….. …..waveform will return to normal

I Rise time…….fastI Rise time…….fast

P

0

I Rise time…….slowI Rise time…….slow

Inspiratory rise time is directly Proportional to inspiratory flow to get proportional Vt is deliverd

PRESSURE waveform………

Time

PIP

PEEP

Ti

Pre

ssur

e

TE

To Increase Mean Airway Pressure….

1. Increase flow

2. Increase peak pressure

3. Lengthen inspiratory time

4. Increase PEEP

5. Increase Rate

MAP…..

PEF

PIF

TV

In severe insp airway obstruction, the wave form can become a plateau. This can become a problem in flow-cycled modes, such as Pressure Support. (asynchrony, W.O.B.)

Flow waveform……Effects of airway resistance/ obstruction

Effects of ed expiratory resistanceFlow waveform……

Air Trapping……… AUTO PEEPAir Trapping……… AUTO PEEP

Inspiration

Expiration

NormalPatient

Time

Flo

w (

L/m

in)

Air-trappingAUTO PEEP

Flow waveform……

Response to Bronchodilator….Response to Bronchodilator….Before

Time

Flo

w

PEFR

After

Long TE

Improved PEFR

Normal TE

To assess response to bronchodilator therapy,…. 1. An increase in peak expiratory flow rate. 2. The expiratory curve should return to baseline sooner.

Flow waveform……

Bronchodilator Response….. F-V loopBronchodilator Response….. F-V loop

2

1

1

2

3

3

VLPS

.VT

Normal

AFTER

Bronchospasm Relief

2

1

1

2

3

3

V.

2

1

1

2

3

3

V.

Assessing Bronchodilator Therapy……

Optimizing Auto –PEEP……

1 2 3

Inspiratory flow pattern…… I –time synchrony

1 : short2 : Normal 3 : Prolonged

Asynchrony leads to……. Low tidal volume delivery Auto-PEEP

Flow waveform……

1 2 3 4 5 60

18 cc

Setting Appropriate I-Time ……….……to get desired V T = 25

PCV…. PIP= 20, Vt (achieved) = 18

Short I – time ……low Vt

volu

me

Time

1 2 3 4 5 6

Flo

w

Time

Setting Appropriate I-Time ……….

25 cc18 cc

Lost VT

1 2 3 4 5 6

1 2 3 4 5 60

Appropriate I – time ……good Vt

volu

me

Time

Flo

w

Inspiratory Cycle off %............................flow cycling

100%

75%

50%

30%25%

Adjusting I-time………

60%

time time

Inspiratory Cycle off %............................flow cycling

10%

time time

Exhalation “spike”

Inspiratory Cycle off %............................flow cycling

Secretions Or water in circuit

F

Flow time wave…….

Time

Exhaled vol taking longer time to reach baseline

VOLUME waveform………………..

Exhaled volume takes longer time to return to baseline……… damp or blocked expiratory filter/valve

Increased Airway resistance

Vol

ume

(ml)

Time (sec)

Air Leak

Air trapping / Air Leak…………Air trapping / Air Leak…………

Exhalation side of the waveform doesn’t return to baseline, it could be 1---- air-trapping (improperly set I-time, emphysema),2---- air leak (ET tube, vent circuit, chest tube, etc.) And can lead to auto-triggering

VOLUME waveform………………..

Air Leak……Air Leak……

VT

ml

30

-10

V

P

F

V

P-V loop

F-V loop

Volume waveform….

VOLUME waveform………………..

Air-trapping….. Resolved…..

NOT all Air-trapping ……… is Pathological……..

Air Trapping….. P-V loop and F-V loopAir Trapping….. P-V loop and F-V loop

•The expiratory portion of the loop doesn’t return to baseline. •This indicates a air trapping/or air leak.

Insp

Exp

Pressure

volu

me

Insp

Exp

Flow PIFR

PEFR

VT

Air trapping on Loops……

At 1st session of vent graphics class…… At 1st session of vent graphics class……

A DUCKY!

AHORSIE

NoA

DOGGIE

MYMOM-IN-LAW

BENDING OVER!

PCV… SIMV

A….Ineffective tidal volume in spontaneous breaths; B….Improved tidal volume during spontaneous breaths.

Volume waveform … trending..guides for weaning

Loops…….Loops…….

Pressure-Volume Loops

Flow-Volume Loops

Pressure-Volume Loops

Flow-Volume Loops

P-V loops……P-V loops……

Lung OverdistentionAirway ObstructionBronchodilator ResponseRespiratory Mechanics WOBFlow StarvationLeaksTriggering Effort

Spontaneous Breath………

Inspiration Expiration

0 20 40 602040-60

0.2

0.4

0.6

Pressure

cmH2O

VT

Clockwise

CPAP

Controlled Breath…….

Expiration

0 20 40 602040-60

0.2

LITERS

0.4

0.6

Paw

cmH2O

Inspiration

VT

Anticlockwise

PEEP

P-V loop and PEEP…..

Assisted Breath…………

Inspiration

Expiration

0 20 40 602040-60

0.2

LITERS

0.4

0.6

Paw

cmH2O

Assisted Breath

VT Clockwise to Counterclockwise

PEEP

Trigger deflection………WOB, T sensitivity

P-V Loops….in Airway ResistanceP-V Loops….in Airway Resistance

“hys

teresis

”exp.

resis

tance

insp.

resis

tance

Insp resistance 1. ETT size too small, 2. tube kinked, 3. patient biting tube, etc.

exp resistance: 1. secretions, 2. bronchospasm, etc.

Compliance……….Compliance……….

Volu

me

Pressure

↓compliance… Loops moves down (angle becomes < 40)…….RDS (HMD), Pleural effusion, consolidation ….moves up (>45) …….. ↑ compliance……. Surfactant therapy

Lung Compliance Changing in P-V Loop (pressure mode)………….Lung Compliance Changing in P-V Loop (pressure mode)………….

Volume

Preset PIP

VT

leve

ls

Pressure

RDS…lung

1.With surfactant2. Emphysematous L

Constant PIP……… variable VT

Lung Compliance Changes and the P-V Loop…. (Volume mode)

Lung Compliance Changes and the P-V Loop…. (Volume mode)

Volume

PIP levels

Preset VT

Pressure

↑C C ↓C

Constant VT………. Variable Pressure

Overdistension……….Overdistension……….

Vol

ume

Pressure

NormalAbnormal

With little or no change in VT

Pressure rises

C20

C dyne

If C20/Cdyne ………..< 1……… Overdistension

PEEP

volu

me

PIP4 6 17 19

P =13

P=13

TV = 12.3 mlCL = 0.95 ml/cm H20

TV = 8.7 mlCL = 0.67 ml/cm H20

Optimizing PEEP…………….

Lowerinflectionpoint

Upperinflectionpoint

Air Trapping….. P-V loop and F-V loopAir Trapping….. P-V loop and F-V loop

•The expiratory portion of the loop doesn’t return to baseline. •This indicates a air trapping/or air leak.

Insp

Exp

Pressure

volu

me

Insp

Exp

Flow PIFR

PEFR

VT

Air Leak…………Air Leak…………

VT

ml

30

-10

V

P

F

V

P-V loop

F-V loop

Volume waveform….

Flow –Volume Loops……

Flow volume loop can be used to assess……Flow volume loop can be used to assess……

Air trapping Airway Obstruction Airway Resistance Bronchodilator Response Insp/Exp Flow Leaks Water or Secretion accumulation Flow Starvation Asynchrony

Flow-Volume Loop……….Flow-Volume Loop……….

Volume (ml)

Inspiration

Expiration

Flow

(L /

min

)

PIFR

PEFR

FRC

VT

Pressure Mode

F-V loops…. variationsF-V loops…. variations

Volume (ml)

Inspiration

Expiration

Flow

(L /

min

)

PIFR

FRC

VT

↓PEFR

“Scooped out” pattern

Increased Airway Resistance……Increased Airway Resistance……

Air Leak…………Air Leak…………

VT

ml

30

-10

V

P

F

V

P-V loop

F-V loop

Volume waveform….

Volume (ml)

Inspiration

Expiration

Flow

(L /

min

)

PIFR

PEFR

FRC

VT

Airway Secretions ……….Water in the CircuitAirway Secretions ……….Water in the Circuit

Looking Trend Data……Looking Trend Data……

Accurate measurement requires a proximal flow sensor.

Compare waves and loops to previous ones after making adjustments, rather than interpreting them in isolation.

Clinical assessment at the bedside very important in the mechanically ventilated child.

Real time pulmonary graphics provide useful information about ventilator performance and interaction with child.

The future: closed loop control of ventilation, including FiO2and PEEP (autopilot of aeroplane)

Summary………………………..

Ref……. 1. Neonatal and Pediatric Pulmonary Graphics: Principles and Clinical Applications, with Bedside Guide

…….Steven M. Donn 2. Rapid Interpretation of Ventilator Waveforms (2ndEdition)….. by Jonathan B. Waugh, Vijay M. Deshpande, Melissa K. Brown and Robert Harwood.3. Ventilator Graphics.. by Scott Richey4. Ventilator Graphics..simplified approach

(2011, 1st edition) Dr Vishram Buche & associates

VENTILATOR GRAPHICS IS ANART OF VENTILATION IN TO SCIENCE OF VENTILATION

Thanks

There is NO COPYRIGHT on this material….

please copy for educational purposes….

: vbuche@gmail.com