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 V T 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 FiO 2 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 V T 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 CVHFJVHFOVSIMV p = p = Number Birth Weight, kg Randomization Age, hrs Alive w/o CLD at 36 wks % 31 48% 44 68% %

Effective frequencies Determinants of PaO 2 Determinants of PaCO 2  P drop down airways HFJV vs. HFOV Similarities

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 /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 RDS High airway resistance upstream of injury restricts Jet gas, promotes healing R aw Problem More ventilation since small V T s 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 gas increases 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 and alveolar 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 Exhaled 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 Tracheal Pressure, cm H 2 O seconds Time 0 0 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:

“Patient Box”

LifePort ET tube adapter ET Tube Connector Jet Port Cap Jet Injection Port 15-mm Connector Pressure Monitoring Line

The LifePort Adapter Jet Port 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. Pressure Monitoring 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 Perceived Lung Volume Servo Pressure Perceived Lung 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

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 PaO 2 Lower P Lower Paw Good PaCO 2 Hypoxemia Higher P Higher Paw Hypocapnia Good PaO 2 Lower P Higher Paw Good PaCO 2 Good PaO 2 P

How much PEEP should one use with HFJV?

Start with PEEP appropriate for IMV IMV Rate = 5-10 bpm Note current SaO 2 on pulse oximeter PEEP may be high enough NO PEEP is too low YES Flip IMV to CPAP mode Finding Optimal PEEP During HFJV * * Don’t be surprised if PEEP = Does SaO 2 drop? (1- 5 min.) Flip back to IMV Rate = bpm Increase PEEP by 1-2 Wait for SaO 2 to return to acceptable value (It may take >30 min.) Does FiO 2 need increased? (15-30 min.) Flip back to IMV if desired (rate = 1-3 bpm) NO Keep PEEP at this level until FiO 2 < 0.40 YES

seconds cm H 2 O CRITICAL "LEAKING" PRESSURE Raise PEEP to oxygenate PIE Patients

Other Patient Management Strategies for HFJV

The Jet in Tandem with CV Jet CV LifePort adapter Ventilation Oxygenation PEEP Valve

2 CO 2 V  f x V T HFV ∆P is key to controlling PaCO 2 Drazen JM, et al. Physiol. Rev. 64: 505, 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.

PIP PEEP I-time.020 FiO2 100% Rate 420 CV HFJV CPAP HIGH LUNG VOLUME STRATEGY Mean lung volume time PaO 2 < 50 no sustained recruitment

PIP PEEP I-time.020 FiO2 100% Rate 420 CV HFJV x LOW PEEP STRATEGY Mean lung volume time no sustained recruitment PEEP is too low!

PIP PEEP I-time.020 FiO2 100% Rate 420 CV HFJV gradual recruitment LUNG VOLUME STRATEGY Mean lung volume time PEEP is the key!

Lung V time P PEEP Low Optimal V

V V Lung time P PEEP Low Optimal 4620

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 PCO 2. CV PEEP is the main determinant of Paw and PO 2.

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: Call the Hotline: HFJV

INO via HFJV

Jet Circuit LifePort adapter "Y" connector Jet CV Sampling line to analyzer INOvent injector module "T" into GAS OUT tubing INOvent * Nitric Oxide + HFJV works well for PPHN