When the smallest thing matters
SLE5000HFOV
Presented
by SAYU ABRAHAM
When the smallest thing matters
High Frequency Ventilation
• Defined by FDA as a ventilator that delivers more than 150 breaths/min.
• Delivers a small tidal volume, usually less than or equal to anatomical dead space volume.
• While HFV’s are frequently described by their delivery method, they are usually classified by their exhalation mechanism (active or passive).
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Differences between HFOV and CMV
CMV HFOV
Rates 0 - 150 180 - 900
Tidal Volume 4 - 20 ml/kg 0.1 - 5 ml/kg
Alv Press 0 - > 50 cmH2O 0.1 - 5 cmH2O
End Exp Vol Low Normalized
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High Frequency Ventilation• Types of HFV’s Approved for use in both Neonates and
Pediatrics• SLE5000 HFOV• SensorMedics 3100A HFOV• Bird Volumetric Diffusive HFPPV
• Types of HFV’s Approved for use in Neonates Only• Bunnell Life Pulse HFJV• Infrasonics Infant Star (discontinued) HFFI
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SLE5000
• Electrically powered, electronically controlled
• Conventional and HFOV ventilator
• Paw of 3 - 35 mbar• Delta P from 4 – 180
mbar• Frequency of 3 - 20 Hz• I:E Ratio 1:1• Active exhalation
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“HFOV”:SLE 2000
Insp. Line Resistor (Trigger sensibility)
Exp. Valve Block
Bias flow 5l/min
Rotating jet
Peep adjustment
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Indications of HFOVNeonatal
RDS/HMDAir leak syndromes
MASPPHNCDH
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Ventilator Induced Lung Injury
• Barotrauma
• Volutrauma
• Stretch Injury
• Biochemical Injury
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Absence of Surfactant
Atelactasis
Tidal Breathing
High Distending Pressures
Airway Stretch / Distortion
Cellular Membrane Disruption
Edema / Hyaline Membrane Formation
Higher FIO2 , Volumes, Pressures
Volutrauma, Barotrauma, Biotrauma
PIE, BPD
Pulmonary Injury Sequence of the neonatal patient:
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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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Ventilator Induced Lung Injury
Premature baboon model
Coalson J. Univ Texas San Antonio
When the smallest thing matters
Ventilator Induced Lung Injury
Premature baboon model
Coalson J. Univ Texas San Antonio
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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; 25:906
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Ventilator Induced Lung Injury
• HFOV with Surfactant as Compared to CMV with Surfactant in the Premature Primate– HFOV resulted in
• Less Radiographic Injury
• Less Oxygenation Injury
• Less Alveolar Proteinaceous Debris
Jackson C AJRCCM 1994; 150:534
Alveolar Protein
0%
5%
10%
15%
20%
25%
30%
CM
V
CM
V-S
HF
OV
HF
OV
-S
Mode
Per
cen
t D
ebri
s
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HFOV
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Theory of Operation
• Oxygenation is primarily controlled by the Mean Airway Pressure (Paw) and the FiO2
• Ventilation is primarily determined by the stroke volume (Delta-P) and the frequency of the ventilator.
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HFOV effectively decouples:
Oxygenation & Ventilation
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HFOV Principle:Pressure curves CMV / HFOV
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Principles of the SLE5000 HFOV
“Super-CPAP” system to maintain lung volume
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Optimized Lung Volume Strategy:
Increase Lung Volume above critical opening pressure to the Optimum and keep it there in
Inspiration and Expiration.
Benefits: - homogenous gas distribution- reduced regional atelectasis- maximized gas exchange area and pulmonary blood flow
- better matching of ventilation/perfusion- reduction of intrapulmonary shunting - reduced Oxygen exposure
When the smallest thing matters
Optimized Lung Volume Strategy:
Decrease Tidal Volumes to less or equal to dead space and increase frequency.
Benefits: - enhanced gas exchange due to combined gas transport mechanisms
- no excessive volume swings- reduced regional over-inflation and stretching
- reduced Volutrauma
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Oxygenation
• The Paw is used to inflate the lung and optimize the alveolar surface area for gas exchange.
• Paw = Lung Volume
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CDP =Lung Volume
CT 1 CT 2CT 3
Paw = CDPContinuousDistendingPressure
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“Open up the lung up
and keep it open!”
Burkhard Lachmann, 1992
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Primary control of CO2 is by the stroke volume produced by the Delta P Setting.
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Regulation of stroke volume
• The stroke volume will increase if– The amplitude increases (higher delta
P)
Stroke volume
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Secondary control of PaCO2 is the stroke volume produced by the set Frequency.
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Regulation of stroke volume
• The stroke volume will increase if– The amplitude increases (higher delta
P) – The frequency decreases (longer cycle
time)Stroke volume
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CDP=FRC=Oxygenation
HFOV Principle:
+ + + + +
- - - - -
AmplitudeDelta P =Tv =Ventilation
I
E
HFOV = CPAP with a wiggle !
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Pressure transmission
Gerstmann D.
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Airway Pressure Transmission HFOV :
Transmission
ET Tube Trachea Alveolus
CDP / MAP= Lungvolume= Oxygenation
Pressure
AmlitudeDelta P =TV =Ventilation
I
E
+ + +
+ + ++ + + +
_ _ _
_ _ __ _ _
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HFOV Mechanisms of Gas Transport
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Mechanisms of HFOV Gas Exchange
• There are six mechanisms of gas exchange during HFOV– Convective
Ventilation– Asymmetrical Velocity
Profiles– Taylor Dispersion– Pendeluft– Molecular Diffusion– Cardiogenic Mixing
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Practical preparation
• Avoid leak around the E.T tube• Tc PO2,CO2,Pulse oxymeter and invasive
blood pressure monitoring• Baseline CXR• Optimize blood pressure and
perfusion(volume replacement and inotropes)
• Muscle relaxant/sedation• Reusable low compliance circuits must be
used
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NURSING CARE• Perform through suction before connecting to the
oscillator.• Assess patient upon commencement of HFOV.Monitor
vital signs, chest wiggle must be evaluated upon initiation and followed closely thereafter. If chest wiggle diminishes it may be ETtube moved or obstructed. Chest wiggle on one side indicates patient developed pneumothorax,thus chest wiggle assessment should be performed after repositioning.
• Auscultation the chest by putting in standby mode.• A closed suction should be used. It is not necessary to
disconnect the patient to suction as this will potentially derecruit lung volumes.
• The point at which the ET tube is cut and secured at lips should be initially noted this measurement is reference.
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Continued………
• Evaluation of lung expansion on CXR• Check capillary refill, skin color and
temperature• Comparing central and peripheral pulses• Monitoring of ECG Tracing• Frequent CXR’s blood gases in initial
stabilization period• Optimal lung volume for oxygenation is 8-9
rib inflation• Blood pressure and perfusion should be
optimized prior to HFOV,any volume replacement should be completed and inotropes commenced if necessary
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Continued………
• Muscle relaxants are not indicated since spontaneous respiratory effort will be a clinical indicator of adequacy of ventilation
• Sedation with opiates is often indicated
THANKYOU
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