Prevention and Treatment of Ventilator-Induced Lung Injury with HFJV Dawn Rost BS, RRT-NPS Clinical...
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Transcript of 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: [email protected]
Remember KISS-KEEP IT SIMPLE SILLY