Getting Inspired by High Frequency Jet Ventilation Clinical Applications and Optimization

Getting Inspired by High Frequency Jet

Ventilation

Clinical Applications

and Optimization

Ventilation Facts• The least traumatic ventilation occurs in the

mid-portion of the P/V curve.

• Lungs are most vulnerable to injury during the recruitment phase.

• A 5 cc/kg VT may not prevent over-expansion and lung injury

• Apply L.O.V.E.

Goals of Assisted Ventilation

• Achieve uniform lung inflation

• Minimize over and under inflation

• Minimize FiO2

• Early appropriate extubation

How should HFV be used with newborn infants?

Potential HFV Applications

1. Prevent Lung Injury

a. Non-homogeneous Lung Disorders

b. Air Leaks (PIE, PTX, etc.)

c. Whenever small VT and Low Paw helps

a. Must use early

b. Must avoid hyperventilation

c. Optimizing PEEP offers huge advantages

2. Treat Lung Injury (Rescue)

2 Trials: Early Use of HFV for RDS

244 65 65254

0.9 1.0 1.00.9

2.7 8 82.7

CV HFJVHFOVSIMV

p = 0.037p = 0.046

Number

Birth Weight, kg

Randomization Age, hrs

Alive w/o CLD at 36 wks

13156%

3148%

4468%

11747%

• Effective frequencies

• Determinants of PaO2

• Determinants of PaCO2

P drop down airways

HFJV vs. HFOVSimilarities

Why does one need HFJV?

Sick lungs aren’t always homogeneous.

We like to think that the lungs look like

this…

with lots of surface area for gas exchange.

Courtesy of Professor Louis De Vos

http://www.ulb.ac.be/sciences/biodic/index.html

Premature lungs look more like

this:

The Premature Lung

• Alveoli have yet to be fully formed

• Surfactant is not yet being adequately produced

• Terminal bronchioles make up the most compliant area of the lungs

Ventilating Premature Lungs

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

Distal airway disruption :

• PIE

• Pneumothorax

• Pneumo- this and that

What we would like to happen:

What really happens:

Ventilating Premature Lungs

Thar she blows!!

Airleaks Originate in Terminal Airways

Positive pressure ventilation damages premature lungs

• Inflammation

• Inhibited alveolar development

• PIE and other airleaks

• Smooth muscle growth in small airways and alveoli

Using small tidal volumes to treat lung injuries is critically

important!

How those small tidal volumes are delivered is also

critically important!

The Jet squirts gas into the lungs faster than any other ventilator.

So what?

High velocity gas shoots right past upper airway leaks!

Using HFJV to Treat BPF

Squirting gas into lungs very rapidly enables the Jet to ventilate Non-Homogenous lung disorders.

PIE RDSHigh airway resistanceupstream of injuryrestricts Jet gas,promotes healing

Raw

Problem

More ventilation since small VTs not

affected by atelectasis, low lung compliance

C L

Problem

HFJV Gas Distribution in Non-Homogeneous Lung Disease

HFJV: less gas to injuries, more gas for RDS!

A Non-Homogeneous Disorder

Interstitial gasincreases airway resistance upstream from leak site.

Tension PIE restricts alveolar expansion.

Pulmonary Interstitial Emphysema

The principal manifestations of injury in premature lungs are

airway narrowing andalveolar disruption.

If we can reduce mechanical ventilation of injured areas of premature lungs, they can heal

and grow new lung parenchyma.

HFJV decreases ventilation where airway resistance is

increased, so injured alveoli can heal and multiply.

• The Jet relies on the lungs for passive exhalation.

• Passive exhalation helps the patient in two ways.

Passive Exhalation

Mucociliary Clearance

CO 2

CO 2

CO

2

CO 2

CO 2Exhaled gas swirls out along airway walls, facilitating mucociliary clearance.

Passive exhalation also enables the Jet to work at lower Paw.

Three Ventilators, Same Blood Gases

HFJV

HFOV

CV

10

15

20

5

Tra

chea

l P

ress

ure

, cm

H2O

seconds0.80.60.40.2

Time

00

Paw

Boros, et al. Ped Pulm. 1989; 7:35-41

PRESSURE WAVEFORM COMPARISON

CHOKE POINTS may develop when:• airways lack structural strength• the chest is squeezed• gas is sucked out of the airway

++

+

+

++

+

+

PEEP

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

Consequences of Active Exhalation

1. A limit to how much Paw can be reduced.

2. Possible interference with venous return, cardiac output.

When is the Jet the HFV of choice?

• Hemodynamic Compromise (e.g., PPHN, cardiac anomalies)

• Air Leak Syndromes

(particularly PIE, Ptx)

• Excessive Secretions (e.g., some pneumonias, MAS)

HFJV vs. HFOV

• Non-Homogeneous Lung Disorders (e.g., when HFOV fails)

Other Conditions When Jet is the HFV of choice:

• Difficult to Wean Patients (e.g., BPD, Chronic Lung Disease)

The “Jet”

Operating instructions: www.bunl.com

“Patient Box”

LifePort ET tube adapter

ET Tube Connector

Jet Port Cap

Jet Injection Port

15-mm Connector

Pressure Monitoring Line

The 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

• Sensitive to changes in patient’s condition

• Help you maintain optimal lung volume without xrays

HFJV Monitoring and Alarms

• Servo Pressure

• Mean Airway Pressure

Monitoring HFJV with High – Low Alarms

The Importance of Servo Pressure

• Servo Pressure = Automatically controlled driving pressure• Servo Pressure changes as perceived lung volume changes

PerceivedLung Volume

Servo Pressure

PerceivedLung Volume

Servo Pressure

Observing Servo Pressure can facilitate patient management

• Improved compliance and/or resistance

• Airleak

• Disconnected Tubing

• Extubation

Servo Increases

Servo Decreases

• Worsened compliance and/or resistance

• Obstruction of ET Tube

• Tension pneumothorax

• Patient needs suctioning

• High Alarm (usually good news):

o improved lung mechanics (compliance or resistance)

o tubing leaks, etc.

Servo Pressure

Servo Pressure

• Low Alarm (always bad news): o degradation of lung mechanics

o atelectasis

o accumulation of secretions

o tension pneumothorax

o right mainstem intubation

o etc.

Mean Airway Pressure

• High Alarm: inadvertent PEEP, gas trapping.

• Low Alarm: tubing leaks or disconnects, inadvertent changes in CV settings, etc.

PIP

PEEP

Paw

Adjusting Airway Pressures to Optimize Arterial Blood Gases

Higher P

Higher Paw

Hypocapnia

Good PaO2

Lower P

Lower Paw

Good PaCO2

Hypoxemia

Higher P

Higher Paw

Hypocapnia

Good PaO2

Lower P

Higher Paw

Good PaCO2

Good PaO2

P

How much PEEP should one use with HFJV?

Start with PEEP appropriate for IMVIMV Rate = 5-10 bpm

Note current SaO2 on pulse oximeter

PEEP may be high enoughNO

PEEP is too low

YES

Flip IMV to CPAP mode

Finding Optimal PEEP During HFJV *

* Don’t be surprised if PEEP = 6-10.

Does SaO2 drop?(1- 5 min.)

Flip back to IMVRate = 5 - 10 bpm

Increase PEEP by 1-2

Wait for SaO2 to returnto acceptable value

(It may take >30 min.)

Does FiO2 need increased?

(15-30 min.)

Flip back to IMV if desired(rate = 1-3 bpm)

NO

Keep PEEP at this leveluntil FiO2 < 0.40

YES

5

10

15

20

30

0.0 2.00.5 1.51.0

seconds

cm H2O

CRITICAL "LEAKING" PRESSURE

Raise PEEP to oxygenatePIE Patients

Other Patient Management Strategies

for HFJV

The Jet in Tandem with CV

JetCV

LifePort adapter

VentilationOxygenation

PEEP Valve

2CO2

V f x VT

HFV ∆P is key to controlling PaCO2

Drazen JM, et al. Physiol. Rev. 64: 505, 1984.Fredberg, JJ. Acta Anaesthesiol. Scand. 33: 170, 1989.

Step Two

Step One

• Recruit collapsed alveoli with IMV when atelectasis is present.

Oxygenation: 2-Step Process

• Stabilize alveoli with adequate PEEP.

PIPPEEP

I-time .020

FiO2 100% 100%

Rate 420

CVHFJVCPAP

--4 4

20 --

HIGH LUNG VOLUME STRATEGY

Meanlung

volume

time

PaO2 < 50 no sustained recruitment

PIPPEEP

I-time .020

FiO2 100% 100%

Rate 420

CVHFJV

x3

2.04 4

20 30

LOW PEEP STRATEGY

Meanlung

volume

time

no sustained recruitment

PEEP is too low!

PIPPEEP

I-time .020

FiO2 100% 100%

Rate 420

CVHFJV

5 - 10

0.58 8

20 20

gradual recruitment

LUNG VOLUME STRATEGY

Meanlung

volume

time

PEEP is the key!

Lung V

time P

PEEP

Low Optimal

4 6 20

V

VVLung

time P

PEEPLow Optimal

4 6 20

Using IMV to recruit collapsed alveoli is a temporary maneuver.

Do not continue to use high CV rate with high PEEP once oxygenation

improves!

Combining CV & HFJV doesn’t have to be Complicated

• Only Jet PIP requires adjustment, to control PCO2.

• CV PEEP is the main determinant of Paw and PO2.

HFJV + CV = Versatility

CV breaths can:

• Recruit collapsed alveoli.

• Dilate or open collapsed airways.

• And, you can add them with or without HFJV breaths.

HFJV + CV: Keep It Simple

• CV settings are usually minimized, except for PEEP

• IMV Rate: 10 bpm zero (CPAP)

• PIP and I-time settings should be set in proportion to Rate.

Summary…

Why HFJV?

1. Very Gentle (prevent CLD?)• Small Tidal Volumes• Low Airway Pressures

2. Easy to Use, Like Conventional Ventilation

• Same principles of gas exchange

• Same setting changes produce same blood gas changes

3. Combined HFJV / CV = Great Versatility

4. Works great with non-homogeneous lung disorders.

• Hemodynamic Compromise

• Air Leak Syndromes

• Excessive Secretions

When is the Jet the HFV of choice?

• Non-Homogeneous Lung Disorders

• Difficult to Wean (BPD, CLD) Patients

Are you Inspired?

• Read the handout

• Website: www.bunl.com

• Call the Hotline: 1-800-800-HFJV

INO via HFJV

Jet Circuit

LifePort adapter

"Y"connector

JetCV

Sampling line to analyzer

INOvent injector module

"T" intoGAS OUT

tubing

INOvent*

Nitric Oxide + HFJV works well for PPHN