Prevention and Treatment of Ventilator-Induced Lung Injury with HFJV Watch this space for explanations of at least some of the slides. If you are viewing this as a web page, you may use your left mouse button to actuate animation. Dawn Rost BS, RRT-NPS Clinical Specialist Bunnell 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?

High Frequency Ventilator LifePulse High Frequency Ventilator “The Jet” Bunnell Hotline 800-800-4358

“WhisperJet” Patient Box Here is a picture of our new Patient Box. Its primary feature is that it is very quiet. I’m very quiet…

HFJV in Tandem with CMV Ventilation Oxygenation PEEP Jet CMV LifePort adapter

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 Adapter Pressure Monitoring Line 15-mm Connector Jet Injection Port Jet Port Cap ET Tube Connector The second key to reducing tidal volumes is the Jet nozzle contained in our little ET tube adapters. The LifePort allows the Jet to be used with conventional ET tubes.

LifePort Adapter Pressure Monitoring Port 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 The PIP measured by the LifePort adapter is filtered to produce the same PIP that one would measure at the distal tip of a Hi-Lo Jet ET tube.

VT = 1 mL/kg VD = 2 mL/kg Flow Streaming They swirl down the airways, splitting at bifurcations, always seeking the path of least resistance in the center of the airways. CO2 The Patient Box and LifePort adapter create flow streaming in the airways. We still have convection and diffusion just like we have during normal breathing and conventional ventilation. The convective element of the process is just using much smaller tidal volumes delivered at correspondingly higher rates, and diffusion is enhanced by almost continuously moving higher PO2 gas closer to the alveoli. VT = 1 mL/kg VD = 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 These are the most important differences between the two HFV modalities. What guidance can we gain from focusing on the differences between HFJV and HFOV.

HFJV Inhalation and Exhalation The path of least resistance for exhaled gas is around the inhalation gas streaming in, along airway walls. CO2 This flow pattern moves secretions towards ETT. The Patient Box and LifePort adapter create flow streaming in the airways. We still have convection and diffusion just like we have during normal breathing and conventional ventilation. The convective element of the process is just using much smaller tidal volumes delivered at correspondingly higher rates, and diffusion is enhanced by almost continuously moving higher PO2 gas closer to the alveoli.

Servo Pressure 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 = driving pressure that provides Flow Understanding Servo Pressure Servo Pressure = driving pressure that provides Flow Servo pressure changes as lung volume changes Servo Pressure Increases Servo Pressure Decreases Volume Increases Volume Decreases Servo pressure changes = early warning of patient changes. Rising Servo Pressure is usually good news. Falling Servo Pressure is always bad news, or at least something that must be attended to such as suctioning. INCREASES DECREASES Improved compliance Worsened compliance and/or resistance (bronchospasm) and/or resistance Tension pneumothorax Increased airleak Tubing leaks Patient needs suctioning

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

Alveolar Recruitment & PaO2 PIP PEEP I-time .020 Rate 420 CV HFJV CPAP 4 20 no sustained recruitment Lung Volume Recruitment only happens when enough PEEP is used as Dr. Allison Froese demonstrated for us with her experiments using bunnies in a body box. The rabbits underwent saline lavage to create the model for RDS. When ventilated with the Jet post-lavage, the Jet’s small tidal volumes could be seen on the plethysmograph’s strip chart, but there was no sustained recruitment of lung volume when the conventional ventilator was in CPAP at 4 cm H2O. On 100% oxygen, we could only get a PaO2 of 50 torr. PaO2 < 50 time

Recruiting with Inadequate PEEP V PIP PEEP I-time .020 Rate 420 CV HFJV 3 2.0 4 20 30 PEEP is too low! no sustained recruitment Then Dr. Froese demonstrated that IMV breaths alone also cannot affect alveolar recruitment when she set the conventional ventilator to deliver long (2-sec I-time), big (PIP = 30 cm H2O) breaths when she pressed the manual breath button. The temporary recruitment afforded by the big breaths could not be sustained at a PEEP of 4. Time

Lung Injury occurs at both ends of the P/V curve Critical Opening Pressure Critical Closing Pressure Over time, babies will experience some degree of lung injury if you are unable to wean. Increasing PIP to address a high PaCO2 will increase further the risk of lung injury. HFJV may be indicated.

Recruiting Lung Volume with IMV Breaths HFJV CV Rate 420 6 PIP 20 20 Higher PEEP enables recruitment! PEEP 8 8 I-time .020 0.4 VL gradual recruitment Now, see what happened when Dr. Froese raised the PEEP to 8 cm H2O and set more typical background IMV at 5-10 bpm using the same PIP as the Jet was using. It only took a few minutes before the strip chart from the body box illustrated full lung volume recruitment. The rabbit’s PaO2 went from 50 to 500 torr after only ten minutes on these settings. Time

What a difference adequate PEEP makes! Low Optimal V Lung time V Again, the X-Y recorder illustrates why we achieved success using higher PEEP. The lung maintained a higher and higher FRD when the PEEP kept the lungs above the critical closing pressure of the alveoli. Now, there is a trap here: what do you do when you achieve success like this in the NICU? What typically happens when you make a ventilator change, and the patient suddenly improves? Doesn’t someone at the bedside say: “Oh, the baby likes these settings! Let’s just leave the ventilators on these settings for now…” ? 4 8 30 P

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 6 HFJV: 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 These are the most important differences between the two HFV modalities. What guidance can we gain from focusing on the differences between HFJV and HFOV.

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: Ventilating Premature Lungs What really happens: What we would like to happen:

PRESSURE WAVEFORM COMPARISON 20 15 CV Tracheal Pressure cm H2O 10 HFOV 5 HFJV 0.2 0.4 0.6 0.8 seconds Time MAP

CHOKE POINTS may develop when: airways lack structural strength the chest is squeezed gas is sucked out of the airway Active exhalation promotes gas trapping by creating choke points..

Back-pressure (higher PEEP/Paw) splints airways open, allowing gas to enter and exit. + Paw One has to use higher PEEP or mean airway pressure to mitigate the airway collapsing effect of active exhalation even in normal lungs.

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 When else would lowering I:E ratio would be helpful/ What disease process? PIE HFOV is fixed at 33% inspiratory time or 1:2 I:E

HFJV vs. CV vs. HFOV Consider the injured lung… These are the most important differences between the two HFV modalities. What guidance can we gain from focusing on the differences between HFJV and HFOV.

Pulmonary Interstitial Emphysema Restrictive Lung Disorder Tension PIE restricts alveolar expansion. Interstitial gas increases airway resistance upstream from leak site. The pathophysiology of PIE is perfect for treatment with HFJV, because of the airway restriction that occurs upstream of the site of injury.

NON-HOMOGENEOUS LUNG DISEASE PIE RDS High airway resistance limits Jet ventilation of injured regions. Atelectatic areas with more patent airways get more Jet ventilation. Raw Problem When the high-velocity HFJV breaths are delivered to lungs with PIE, the high velocity tidal volumes will not penetrate into the injured parts of the lungs because airway resistance there is too high. By default, the HFJV breaths will preferentially go where there is lower airway resistance, which in the case of premature infants will be where RDS is more of a problem. This is the perfect way to distribute gas in such lungs, where we want to avoid ventilating the damaged part of the lungs, and we want more gas to go towards areas that are under inflated. C L Problem With HFJV: less gas to PIE areas, more gas to RDS areas.

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

All Sensors Pressure Sensor Honeywell AWM43600V Flow Sensor All Sensors Pressure Sensor This is a schematic diagram of the lung model to show the placement of the flow and pressure sensors, the number of generations in the model etc. 7 bifurcation generations and 8 airway generations.

Heterogeneous Lung Model This is the model we developed to mimic the extremes of airway resistances in the lungs of a premature baby with PIE.

Gas Distribution in Heterogeneous Lung Model   Peak Pressures (cmH2O) Peak Flows (SLPM) Airway Caliber: Large Small CMV PIP=35 35 33 0.54 0.51 HFJV 19 9.9 3.91 0.59 Bunnell LifePulse; rate=420bpm, I-time=0.02sec CV (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.

Minute Volumes (mL/min) Gas Distribution in Heterogeneous Lung Model   Tidal Volumes (mL) Minute Volumes (mL/min) Airway Caliber: Large Small CMV PIP=35 4.2 3.9 210 194 HFJV 1.2 0.4 524 185 Volumes through larger tubes ~ 3x those through smaller tubes.

PIE Study Conclusions 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 Given physics of Jet ventilation and the pathophysiology of PIE, one would expect good results from a randomized controlled study, and that is exactly what happened in the latter half of the 1980s. Had we known how to manage PEEP better in those days, the results would have been even better. (Keszler M, Donn SM, Bucciarelli RL, et al., 1991)

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

Nitric Oxide Delivery with the Jet iNO Vent Jet CV "T" into GAS OUT tubing To insert iNO adapters, cut green Jet tubing here and here. " T " in iNO Vent flow sensor / delivery system LifePort adapter " T " connector Sampling line to analyzer

Eric Coates, MD Neonatology Fellow Short Term Outcomes of Near Term Neonates with Pulmonary Hypertension Treated with Inhaled Nitric Oxide and either High Frequency Oscillatory Ventilation or High Frequency Jet Ventilation Eric Coates, MD Neonatology Fellow J Perinatol. 2008 Jun 26. EPUB

Brenner Children’s Hospital (BCH)

Primary Outcomes: HFOV/iNO v. HFJV/iNO

Multivariate Analysis: Need for ECMO Odds Ratio 95% CI HFOV/iNO v. HFJV/iNO 12.5 1.4 - 108 a/A Oxygen Ratio ≥ 0.1 0.08 0.009-0.7 12 fold greater risk of needing ECMO if HFOV/iNO used @ BCH compared to if HFJV/iNO used when controlling for a/A oxygen ratio

Summary Patients treated with HFJV/iNO at BCH were less likely to need ECMO, even after controlling for a/A oxygen ratio at baseline

Limitations Small sample size Single institution Retrospective data collection Missing data points Differences in severity of illness Unidentifiable changes in care over the 2 epochs

Users Guide to Optimizing HFJV 7 Steps to Success Users Guide to Optimizing HFJV

Lung Protective Ventilation* with HFJV Recruitment IMV from Conventional Vent Positive End-Expiratory (PEEP) & Mean Airway Pressure (MAP) Stabilization Protection HFJV – Most Gentle Ventilation

#1 Step to Success “Plan Ahead” When will you start HFJV?

#1: Start Early When everything else has failed? When HFOV has failed? When “Lung Protective CMV” has failed? When NCPAP has failed?

Utah Valley MC Criteria* Whenever PIE or other air leaks appear Whenever excessive secretions (pneumonias, MAS) appear Whenever ventilated patients have cardiac output problems 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

The Smaller and stiffer the Lungs, the Faster You Can Go 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 When else would lowering I:E ratio would be helpful/ What disease process? PIE

BPD / Pulmonary Hyperinflation Consider a model alveolus sur-rounded by interstitial emphysema. Where is the gas trapped? Will lowering PEEP help? Or will it just make matters worse? Try using no IMV, moderate PEEP, and low HFJV rate.

HFJV for Chronic Lung Disease Children’s of LA Retrospective Study*: 10 Infants with CLD & Pneumonia/Sepsis, > 4 weeks old, on 100% O2 and HFOV * Friedlich et al, J. Maternal-Fetal & Neonatal Medicine 2003; 13:398-402

HFJV after HFOV for CLD Hrs on HFJV - 1 2 9 24 FiO2 0.97 0.81 0.62 0.54 MAP 14 11 9.3 9.0 O.I.* 29 18 10 9/10 survived and discharged on O2 . * O.I. = MAP x %O2 / PO2

#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 Active PIP PEEP PIP PEEP MAP MAP PEEP LifePort adapter

Don’t let the MAP fall when initiating HFJV !! MAP and HFJV Don’t let the MAP fall when initiating HFJV !! CV HFJV = Gentle Ventilation MAP PEEP You must raise PEEP to maintain MAP for Stabilization / Oxygenation. Pressure swings from Jet Whether coming from CV of HFOV, take note of the monitored MAP from the HFJV prior to start-up and match. Increase PEEP to match. Time

Monitoring HFOV with the Jet Jet in Standby Mode PIP PEEP MAP LifePort adapter

Monitoring Manual Ventilation with the Jet Jet in Standby Mode PIP PEEP MAP LifePort ETT adapter

Adjust HFJV PIP to manage PaCO2 #4 Step to Success Adjust HFJV PIP to manage PaCO2

∆P (PIP - PEEP) creates VT HFJV Controls PaCO2 ∆P (PIP - PEEP) creates VT 2 VCO2 ≈ 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: CMV breaths recruit; PEEP stabilizes Push CMV => CPAP mode whenever SaO2 is stable Any time SaO2 drops when you lower CMV rate, MAP is too low; so raise PEEP!

Find & Set Optimal PEEP V P Start HFJV, lower CV rate to 5, and keep alveoli from collapsing by maintaining MAP with increased PEEP : Assume you’re using CV with PEEP = 5, MAP = 9: 8 MAP 9 Maintain HFJV at this PEEP level, weaning FiO2 to maintain target SaO2 until FiO2 ~ 30%. Then switch CV to CPAP mode to test PEEP. Maintain CV = 5 bpm & adjust FiO2 to stabilize SaO2 at 90%. Does SaO2 fall when 5 IMV breaths CPAP? If SaO2 falls, increase PEEP as necessary to keep SaO2 stable with HFJV + CPAP. V PEEP 5 7 25 P

#6 Step to Success “Stay on Track” Monitor Servo Pressure, Pulse Oximetry, and Transcutaneous PCO2 Be patient!

Monitor Servo Pressure 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…… 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

More time for exhalation HFJV Rate I:E Ratio 600 bpm 1 : 4 420 1 : 6 360 1 : 7 300 1 : 9 When else would lowering I:E ratio would be helpful/ What disease process? PIE 240 1 : 12 Patient is on CPAP > 90% of the time!

It’s time to extubate when… Patient is breathing spontaneously. HFJV PIP < 15, PEEP < 8, FiO2 < 0.3 20 Set Nasal CPAP = HFJV MAP P 15 cm H2O 10 5 0.0 0.5 1.0 1.5 2.0 Time, seconds

*Society of Critical Care Medicine Mantra of SCCM* Learn It 32 years of research 90,000 infants HFJV Improve It Deliver It 24 years of clinical applications How we deliver it has improved dramatically over all these years! Measure It *Society of Critical Care Medicine

HFJV works especially well: to prevent lung injury to treat airleaks & other lung injuries to treat non-homogeneous lung disease to clear excessive airway secretions (MAS) when respiratory failure is accompanied by hemodynamic problems (PPHN, CDH, cardiac anomalies, post cardiac surgery, etc.)

Critical Closing Pressure Reacting appropriately to Servo Pressure changes will enable continuous Lung Protective HFJV. Critical Closing Pressure Gentle, open-lung, lung-protective ventilation … V P

Bunnell Inc. HOTLINE 800-800-4358 Website www.bunl.com Email: Greg.Shelton@bunl.com Remember KISS- KEEP IT SIMPLE SILLY