Dr.ALLAM ABUHAMDA CONSULTANT NEONATOLOGIST

1. CONSULTANT
NEONATOLOGIST
DR ALLAM ABUHAMDA
SLE 5000
HFOV

2. Introduction
• 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)

3. Introduction
• Henderson first published his findings in
1915, assessing dead space relationship in
ventilation.
• He stated, “there may easily be a gaseous
exchange sufficient to support life even
when Vt is considerably less than dead
space

4. 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

5. 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

6. Indications of HFOV
Neonatal
RDS/HMD
Air leak syndromes
MAS
PPHN
CDH

7. Ventilator Induced Lung Injury
• Barotrauma
• Volutrauma
• Stretch Injury
• Biochemical Injury

8. Absence of Surfactant
Atelactasis
High Distending Pressures
Airway Stretch / Distortion
Cellular Membrane Disruption
Edema
Higher FIO2 , Volumes,
Pressures
PIE, BPD
Pulmonary Injury Sequence
of the neonatal patient:

9. 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.

10. Ventilator Induced Lung Injury
Premature baboon model
Coalson J. Univ Texas San Antonio

11. 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

12. HFOV Principle:
Pressure curves CMV / HFOV

13. 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

14. HFOV

15. 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.

16. HFOV effectively decouples:
Oxygenation & Ventilation

17. HFOV Principle:
Pressure curves CMV / HFOV

18. 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

19. 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

20. “Open up the lung up
and keep it open!”
Burkhard Lachmann, 1992

21. Primary control of CO2 is by the stroke volume
produced by the Delta P Setting.

22. Regulation of stroke volume
• The stroke volume will increase if
– The amplitude increases (higher delta P)
Stroke
volume

23. Secondary control of PaCO2 is the stroke volume
produced by the set Frequency.

24. Regulation of stroke volume
• The stroke volume will increase if
– The amplitude increases (higher delta P)
– The frequency decreases (longer cycle time)
Stroke
volume

25. CDP=FRC=
Oxygenation
HFOV Principle
+ + + + +
- - - - -
Amplitude
Delta P =
Tv =
Ventilation
I
E

26. Pressure transmission
Gerstmann D.

29. Airway Pressure Transmission HFOV :
Transmission
ET Tube Trachea Alveolus
CDP / MAP
= Lungvolume
= Oxygenation
Pressure
Amlitude
Delta P =
TV =
Ventilation
I
E
+ + +
+ + +
+ + + +
_ _ _
_ _ _
_ _ _

30. HFOV Mechanisms of Gas
Transport

31. 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

33. 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

34. 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.

35. Precautions
 If chest wiggle diminishes it may be
ET tube moved or obstructed.
 Chest wiggle on one side indicates
patient developed pneumothorax,thus
chest wiggle assessment should be
performed after repositioning

36. Precautions
 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

37. Precautions
 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

38. Precautions
 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

39. Precautions
 Muscle relaxants are not indicated
since spontaneous respiratory effort
will be a clinical indicator of adequacy
of ventilation
 Sedation with opiates is often
indicated

40.  THANKS