VIASYS HEALTHCARE INTERNATIONAL

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VIASYS HEALTHCARE INTERNATIONAL
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Oslo, November 2006High Frequency Oscillation

• SensorMedics 3100

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High Frequency Ventilation Modes

• HFPPV High Frequency Positive Pressure
  Ventilation
• HFFI High Frequency Flow Interruption
• HFJV High Frequency Jet Ventilation
• HFOV High Frequency Oscillating Ventilation

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Pulmonary Injury Sequence

• There are two injury zones during mechanical
  ventilation
• Low Lung Volume Ventilation tears adhesive
  surfaces
• High Lung Volume Ventilation over-distends,
  resulting in Volutrauma
• The difficulty is finding the Sweet Spot

Froese AB, Crit Care Med 1997 25906
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Sensormedics 3100A HFO Ventilator 2 Principles
1) Oxygenation (O2) CPAP 2) Ventilation (CO2)
Oscillation
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Principle 1
CDP Adjust Valve
ET Tube
Oscillator
Patient
BIAS Flow
Increase Lungvolume with a super
CPAP system
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Optimized Lung Volume Strategy
CT Scan RDS pig model 3 kg
Continuous Distending Pressure 5 cm H2O
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Optimized Lung Volume Strategy
CT Scan RDS pig model 3 kg
Continuous Distending Pressure 12 cm H2O
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Optimized Lung Volume Strategy
CT Scan RDS pig model 3 kg
Continuous Distending Pressure 20 cm H2O
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CT 2
CT 1
CT 3
CDP Lung Volume
Paw CDP
Continuous Distending Pressure
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Oxygenation-Pressure Curve
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Principle 2
CDP Adjust Valve
ET Tube
Oscillator
Patient
BIAS Flow
Decrease TVs to physiological dead space and
increase frequency (0.1 2ml/Kg)
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(No Transcript)
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Optimized Lung Volume Strategy
2.) Decrease Tidal Volumes to less or equal then
dead space and
increase frequency !
Benefits - enhanced gas exchange doe to
combined gas transport
mechanisms - no excessive
volume swings - reduced regional
overinflation and stretching -
reduced Volutrauma
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GAS EXCHANGE IN HFOV
1.) Convection (Bulk Flow) Ventilation 2.)
Asymetrical Velocity Profile 3.) Taylor
Dispersion 4.) Molecular Diffusion 5.)
Pendelluft 6.) Cardiogenic Mixing
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SUGGESTED READING

• Chang HK. Mechanisms of gas transport during
  ventilation by HFOV, Brief Review, J Appl
  Physiol, 1994
• Schindler M, et al. Effect of Lung Mechanics on
  Gas Transport During HFO. Pediatric Pulmonology,
  1991

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Pressure transmission CMV / HFOV

• Distal amplitude measurements with alveolar
  capsules in animals, demonstrate it to be greatly
  reduced or attenuated as the pressure traverses
  through the airways.
• Due to the attenuation of the pressure wave, by
  the time it reaches the alveolar region, it is
  reduced down to .1 - 5 cmH2O.

Gerstman et al
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Airway Pressure Transmission HFOV
Pressure
ET Tube
Trachea
Alveolus
Transmission
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HFOV PrinciplePressure curves CMV / HFOV
Injury
Injury
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CMV Stable Aveoli
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CMV Instable Aveoli versus HFOV
Carney et al. Crit Care Med 200533S122-S128
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CMV Instable Aveoli versus HFOV - 2
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Dynamic Multiscan CT Method
airway pressure
CT-acquisition
time
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After lavage, Step up
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After lavage, Step down
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Dynamic Multiscan CT Results
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D Pressure (Amplitude) controls CO2
CDP controls O2
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CLINICAL APPLICATIONS

• Neonatal
• Prematurity / RDS
• Surfactant Distribution
• PPHN
• Pneumonia's
• Meconium Aspirations
• Blood Aspirations
• Hypoplasias
• CDH
• Pulmonary Hypoplasia
• gt 24 hrs. gt 40 FiO2

• Neonatal Airleaks
• PIE
• Pneumothoraces
• Pneumomediastinum
• Pneumoperitoneum

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Pulmonary Injury Sequence

• If we cannot prevent the injury sequence , then
  the
• target goal is to interrupt the sequence of
  events !

• High Frequency Oscillation does not reverse
  injury,
• but will interrupt the progression of injury

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HFOV effectively decouplesOxygenation
Ventilation
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3100 A HFOV Resume

• Less Oxygen exposure
• Stable lung inflation
• Recruitment of alveolar space
• Improved matching V/Q
• Reduction of Volutrauma
• No conventional breaths
• Less Volume swings
• No high peak pressures
• Active Exhalation
• Reduces Airtrapping
• Reduces Airway stretch
• Sufficient Humidification
• less risk NTB

HFOV effectively decouples
Oxygenation and
Ventilation