Prevention and Treatment of Ventilator-Induced Lung Injury with HFJV Dawn Rost BS, RRT-NPS Clinical...

Prevention and Treatment of Ventilator-Induced

Lung Injurywith

HFJVDawn Rost BS, RRT-NPSClinical SpecialistBunnell Inc.

Objectives

• What is Jet Ventilation, What makes it Unique?

• When and Why does it work Better Than other Modes of Ventilation?

• How can you Apply HFJV most Effectively?

LifePulseHigh

Frequency Ventilator

“The Jet”Bunnell

Hotline800-800-4358

I’m very quiet…

“WhisperJet” Patient Box

HFJV in Tandem with CMV

Jet CMV

LifePort adapter

Ventilation Oxygenation

PEEP

Jet Ventitlation•The LifePulse is Pressure-Limited, Time-Cycled, like most simple conventional ventilators

•The LifePulse becomes a Jet Ventilator once Flow Reaches the LifePort ETT Adapter

•The Jet delivers Small VTs at Rapid Rates via jet nozzle Utilizing the Bernoulli Principle

“LifePort” ETT AdapterPressure Monitoring Line

15-mm Connector

Jet Injection Port

Jet Port Cap

ET Tube Connector

LifePort Adapter

JetPort

Inspired gas is injected down the ETT in high velocity spurts

PIP is measured here and filtered to

estimate PIP at the tip of ETT

PressureMonitoring

Port

Flow Streaming

CO2

CO2

CO2

CO2

CO 2

CO 2

CO2

They swirl down the airways, splitting at bifurcations, always seeking the path of least resistance in the center of the airways.

VT = 1 mL/kgVD = 2 mL/kg

Flow Streaming

Maintaining a Brief I-time :

• Ensures that VT Remains Independent of Rate

• Enables longer Expiratory Times

• Makes Distribution of Ventilation Dependent on RAW

HFJV Inhalation and Exhalation

CO2

CO2

CO2

CO2

CO 2

CO 2

CO2

This flow pattern moves secretions towards ETT.

The path of least resistance for exhaled gas is around the inhalation gas streaming in, along airway walls.

• Servo Pressure is the Driving Pressure for HFJV

• It is Feedback Controlled by the Jets Micro-Processor to Adjust Gas Flow

• Monitored PIP is Maintained at Set PIP

Servo Pressure

• Servo Pressure = driving pressure that provides Flow

• Servo pressure changes as lung volume changes

DECREASES

Worsened complianceand/or resistance (bronchospasm)

Tension pneumothorax

INCREASES

Improved complianceand/or resistance

Increased airleak

Tubing leaks

Servo Pressure Decreases

Volume Decreases

Servo Pressure Increases

Volume Increases

• Servo pressure changes = early warning of patient changes.

Understanding Servo Pressure

Patient needs suctioning

HFJV: Easy to Use•The Jet has only 3 controls•TI

–Usually held Constant at Minimum of .020 seconds

•PIP•Rate

–PIP & Rate Control Minute Volume & PCO2

Conventional Ventilator Role

CMV’s affect on PO2 is limited to:• Utilization of 0 – 10 bpm, Depending upon

the Need for Alveolar Recruitment, and• Raising the PEEP to Maintain MAP for Proper

Lung Volume and Alveolar Stability

LungVolume

time

PaO2 < 50

PIPPEEPI-time .020

Rate 420

CVHFJVCPAP

4 420 0

Alveolar Recruitment & PaO2

no sustained recruitment

V

Time

PIPPEEPI-time .020

Rate 420

CVHFJV 3

2.04 4

20 30

no sustained recruitment

PEEP is too low!

Recruiting with Inadequate PEEP

Lung Injury occurs at both ends of the P/V curve

Critical Opening Pressure

Critical Closing Pressure

gradual recruitment

VL

Time

PIPPEEPI-time .020

Rate 420

CVHFJV6

0.48 8

20 20 Higher PEEP enables recruitment!

Recruiting Lung Volume with IMV Breaths

CMV Limitations

• CMV (“Sigh” breaths) are most useful

for alveolar recruitment, but contra-

indicated when airleaks are present• Once oxygenation improves, sigh

breaths should be discontinued

because they increase the risk of

causing airleaks

Rate PIP TI PEEP CMV: 20 20 0.4 6HFJV: 420 30 0.02

HFJV vs. CV vs. HFOV

One has to understand how lungs work, as well as how HFJV works, to appreciate and predict why HFJV works when other approaches don’t

Ventilating Premature Lungs

Distal airway rather than primitive alveolus are the most compliant part of the respiratory tract.

Distal airway disruption :

• PIE• Pneumothorax• other bad stuff

What we would like to happen:

What really happens:

Ventilating Premature Lungs

HFJV

HFOV

CV

MAP

seconds0.80.60.40.2

10

15

20

5

Tra

che

al P

ress

ure

c

m H

2O

Time

0

0

PRESSURE WAVEFORM COMPARISON

CHOKE POINTS may develop when:

• airways lack structural strength• the chest is squeezed• gas is sucked out of the airway

++

+

+

+

+

+

+

Paw

Back-pressure (higher PEEP/Paw) splints airways open, allowing gas to enter and exit.

Consequences of Active Exhalation

There is a limit to how much Paw can be reduced without causing gas trapping.

Consequences of Passive Exhalation

There is a limit to how fast you can ventilate without causing gas trapping. Remember I:E

HFJV Rate I : E

600 bpm 1 : 4

420 bpm 1 : 6

360 bpm 1 : 7

300 bpm 1 : 9

240 bpm 1 : 12

HFOV is fixed at 33% inspiratory time or 1:2 I:E

HFJV vs. CV vs. HFOV

Consider the injured lung…

Restrictive Lung Disorder

Interstitial gasincreases airway resistance upstream from leak site.

Tension PIE restricts alveolar expansion.

Pulmonary Interstitial Emphysema

PIE RDSHigh airway resistance limits Jet ventilation of injured regions.

Raw Problem

Atelectatic areas with more patent airways get more

Jet ventilation.

C L Problem

NON-HOMOGENEOUSLUNG DISEASE

With HFJV: less gas to PIE areas, more gas to RDS areas.

Comparison of HFV and CV in Mechanical Ventilation of a

Neonatal Heterogeneous Lung Disease Model

Hills SR, Bunnell JB

Department of Bioengineering, University of Utah and Bunnell Inc, Salt Lake City, UT, USA

Snowbird 2008

“In CV, nearly 100% of set PIP reached the distal airways”

Honeywell AWM43600V

Flow SensorAll Sensors

Pressure Sensor

Heterogeneous Lung Model

Peak Pressures (cmH2O)

Peak Flows(SLPM)

Airway Caliber: Large Small Large Small

CMV PIP=35 35 33 0.54 0.51

HFJV PIP=35 19 9.9 3.91 0.59

Gas Distribution in Heterogeneous Lung

Model

Bunnell LifePulse; rate=420bpm, I-time=0.02secCV (Bear Cub BP2001; rate=50bpm, I-time=0.4sec) using peak inspiratory pressures (PIP) of 35 with positive end expiratory pressures (PEEP) of 5 cmH2O.

Tidal Volumes (mL)

Minute Volumes (mL/min)

Airway Caliber: Large Small Large Small

CMV PIP=35 4.2 3.9 210 194

HFJV PIP=35 1.2 0.4 524 185

Gas Distribution in Heterogeneous Lung

Model

Volumes through larger tubes ~ 3x those through smaller tubes.

• HFJV leads to the resolution of PIE more frequently than does CV

• HFJV results in more rapid improvement of PIE than does CV

• HFJV provides better gas exchange at lower airway pressures compared to CV

• HFJV does not increase the incidence of important complications

• HFJV improves survival in babies with PIE

(Keszler M, Donn SM, Bucciarelli RL, et al., 1991)

PIE Study Conclusions

Common Jet Applications

Non-Homogenous Lung Disorders:• RDS complicated by PIE, PTX, etc.• Meconium aspiration and other

pneumonias (excessive secretions)• ARDS / Acute lung injury in PICUs• BPD / Chronic Lung Disease in

NICUs

Other Jet Applications• Respiratory failure with

hemodynamic compromise (PPHN, cardiac anomalies, etc.)

• Congenital Diaphragmatic Hernia and Pulmonary Hypoplasia

LifePort adapter

" T " connector

Jet

Nitric Oxide Delivery with the Jet

CV "T" into

GAS OUT

tubing

iNO Vent

Sampling line to analyzer

" T " in iNO Vent flow

sensor / delivery system

To insert iNO adapters, cut green Jet tubing here and here.

7 Steps to Success

Users Guide to

Optimizing HFJV

Lung Protective Ventilation* with HFJV

Recruitment

Protection

IMV from Conventional Vent

Positive End-Expiratory (PEEP) & Mean Airway Pressure (MAP)

Stabilization

HFJV – Most Gentle Ventilation

#1 Step to Success“Plan Ahead”

When will you start HFJV?

#1: Start Early

1. When everything else has failed?

2. When HFOV has failed?3. When “Lung Protective CMV”

has failed?4. When NCPAP has failed?

Utah Valley MC Criteria*1.Whenever PIE or other air leaks

appear

2.Whenever excessive secretions (pneumonias, MAS) appear

3.Whenever ventilated patients have cardiac output problems

4.Whenever HFOV fails (i.e., when RDS starts evolving into CLD) * 1990

#2 Step to Success“Start HFJV with Rational Settings”

Choose an HFJV Rate to

Match Patient Size and

Condition

Higher HFJV Rates

The Smaller and stiffer the Lungs, the

Faster You Can Go

Lowering HFJV Rates• Lowering Jet Rate Lengthens E-Time

– Ti is remains set at .02 seconds

• Remember that Exhalation is Occurring through Obstructed Airways

• May Encourage Spontaneous Breathing• May Hasten Extubation

HFJV Rate I : E

600 bpm 1 : 4

420 1 : 6

360 1 : 7

300 1 : 9

240 1 : 12

BPD / Pulmonary Hyperinflation

Where is the gas trapped?Will lowering PEEP help?

Or will it just make matters worse?

Consider a model alveolus sur-rounded by interstitial emphysema.

Try using no IMV, moderate PEEP, and low HFJV rate.

#3 Step to Success“Make a commitment to MAP!”

Preserve existing lung volume

& oxygenation by not allowing

MAP to fall at HFJV initiation

Monitor CMV with Jet in Standby Mode

MAP

LifePort adapter

Standby Mode Active

PIP PEEP

MAPPIP PEEP

PEEP

MAP and HFJV

HFJV = Gentle Ventilation

Time

CV

You must raise PEEP to maintain MAP for Stabilization /

Oxygenation.

MAP

PEEP

Don’t let the MAP fall when initiating HFJV !!

Monitoring HFOV with the Jet

LifePort adapter

Jet in Standby ModePIPPEEP MAP

Monitoring Manual Ventilation with the Jet

LifePort ETT adapter

Jet in Standby ModePIPPEEP MAP

#4 Step to Success

Adjust HFJV PIP to

manage PaCO2

HFJV Controls PaCO2

∆P (PIP - PEEP) creates VT

VCO22≈ f x VT

HFJV VT ≈ 1 mL/Kg

≈ 10x smaller than CMV VTs

#5 Step to Success“Find & Set Optimal PEEP”

Use CMV “sigh”

breaths to find optimal

PEEP

General Rules:1. CMV breaths recruit; PEEP

stabilizes2. Push CMV => CPAP mode

whenever SaO2 is stable

3. Any time SaO2 drops when you lower CMV rate, MAP is too low; so raise PEEP!

Find & Set Optimal PEEP

V

P5 8 25

Start HFJV, lower CV rate to 5, and keep alveoli from collapsing by maintaining MAP with increased PEEP :

7

Maintain CV = 5 bpm& adjust FiO2 to stabilize SaO2 at 90%.

PEEP

Then switch CV to CPAP mode to test PEEP. Maintain HFJV at this PEEP level, weaning FiO2 to maintain target SaO2 until FiO2 ~ 30%. If SaO2 falls, increase PEEP as necessary to keep SaO2 stable with HFJV + CPAP.

Does SaO2 fall when 5 IMV breaths CPAP?

Assume you’re using CV with PEEP = 5, MAP = 9:

MAP

9

#6 Step to Success“Stay on Track”

Monitor Servo Pressure,

Pulse Oximetry, and

Transcutaneous PCO2

Be patient!

• If S.P. you may need to wean PIP to keep PaCO2 and pH in target range

• If S.P. you may need to suction, re-position ETT, or treat bronchospasms or pneumothoraces……

Monitor Servo Pressure

• If ever in doubt, call us: 800-800-HFJV, available 24/7/365

#7 Step to Success“Don’t bail out early!”

Wean to nasal CPAP

As oxygenation improves:• Wean big breaths first

(Get CV into CPAP mode)

• Wean FiO2 before PEEP/MAP

As ventilation improves

• Reduce HFJV PIP first• Reduce HFJV Rate to

encourage spontaneous breathing

HFJV Rate I:E Ratio More timeforexhalation

Patient is on CPAP> 90% of the time!

600 bpm 1 : 4

420

360

300

240

1 : 6

1 : 7

1 : 9

1 : 12

5

10

15

20

0.0 0.5 1.0

Time, seconds

cm H2O

P

2.01.5

It’s time to extubate when…

Patient is breathing spontaneously.HFJV PIP < 15, PEEP < 8, FiO2 < 0.3

Set Nasal CPAP = HFJV MAP

Mantra of SCCM*

*Society of Critical Care

Medicine

Learn It

Improve It

Measure It

Deliver ItHFJV

32 years of research

24 years of clinical

applications

90,000 infants

How we deliver it has improved dramatically

over all these years!

HFJV works especially well:

1) to prevent lung injury

2) to treat airleaks & other lung injuries

3) to treat non-homogeneous lung disease

4) to clear excessive airway secretions (MAS)

5) when respiratory failure is accompanied by hemodynamic problems (PPHN, CDH, cardiac anomalies, post cardiac surgery, etc.)

Reacting appropriately to Servo Pressure changes will enable continuous

Lung Protective HFJV.

V

P

Critical Closing Pressure

Gentle, open-lung, lung-protective ventilation …

Bunnell Inc.• HOTLINE 800-800-4358

• Website www.bunl.com• Email: Greg.Shelton@bunl.com

Remember KISS-KEEP IT SIMPLE SILLY