HIGH FREQUENCY VENTILATOR FOR NEONATES NEONATAL VENTILATOR PPHN,MECHANICAL VENTILATION,ADVANCE VENTILATION,NITRIC OXIDE,SLE 5000,SENSOR MEDICS DR VINIT PATEL

1. HIGH FREQUENCY
VENTILATION
DR VINIT PATEL

2. Why this revolution……
• Intact survival
• Not only lung injury, also neurological
damage secondary to ventilation

3. Why HFV?
• Atelectrauma
• Volutrauma
• Barotrauma
• Bio-trauma
• VILI results in CLD
• HFV – Gentler ventilation
• Toimprove gas exchange in severe respiratory
failure

4. Definition
•Delivery of small tidal volume (Tidal volume
≤Anatomic Dead Space) at supraphysiologic
frequencies.

5. TYPES OF HFV:
Based on characteristic of exhalation (Active /Passive/
Hybrid )and source of generation
– 4 types
1. HFOV
2. HFJV
3. HFFI
4. HFPPV

7. HFPPV
• Refers to CMV which operates at rate of
60-150/min
• No different equipment required
• Very small I-time is used and flow is
generated through pneumatic valve

9. Mechanismofgas exchange
1. Directbulkflow Convection
2. Taylordispersion
3. Pendelluft - motion of air between lung
units with different time constants
4. Asymmetricvelocityprofiles
5. Cardiogenicmixing
6. Molecular diffusion - responsible for gas
exchange across alveolar /capillary
membrane

10. Convection, Transit Time and
Direct Ventilation
Convecti
on
 is the transport of air flow at
a constant equal velocity
that is parabolic in shape.
TO SHORT PATH LENGTH
UNITS THAT BRANCH
OFF FROM PROXIMAL
AIRWAYS

11. Taylor
Dispersion

12. PENDELLUFT
EFFEC
T

13. Asymmetric
velocity
profiles

14. Cardiogenic Mixing
As the heart beats the heart provides additional peripheral
mixing by exerting pressure against the lungs during
contraction of the heart.
This pressure promotes the movement of gas flow
through the neighboring parenchymal regions.

15. Collateral VentilationMolecular Diffusion
Maintaining a constant
distending pressure with HFV
within the lungs along with
movement of gas molecules
promotes gas diffusion across
the alveolar membrane, at a
faster rate.
Collateral ventilation
increases with HFV due to
connections between the
alveoli
 (Pores of Kohn)

17. Open lung ventilation strategy
Goal in open lung ventilation is to keep alveoli at SAFE WINDOW – less
prone atelectrauma , better gas exchange & less Pulmonary vascular
resistance(PVR)

18. Pressure & volume swing in HFV & CMV
• During CMV,there are swing between Zones of Injury from
inspiration to expiration
• During HFOV,entire cycle operates in the safe window & avoid the
injury zones

19. Alveolus in CV and HFV

21. Pressure transmission in HFOV
• With CMV,the pressure exerted by the ventilator propagate through the
airway with little dampening
• With HFOV,there is attenuation of pressures as air moves towards the
alveolar level

22. Settings
• Mean Airway Pressure:- Averagepressure
throughout respiratory cycle
• Amplitude: size of pressure wave or tidal
volume
• Frequency: number of breaths per minute

25. Time X

26. Time X

28. Indications
• Failure of conventional ventilation(OI is
>15)
• PPHN
• Reduced compliance- Lung hypoplasia
• RDS/ARDS
• Airleak syndrome- Pneumothorax,PIE,BPF
• Meconium aspiration
• BPD
• Pneumonia
• Atelectasis

29. Options
• Early Intervention-Application of HFOV to an infant within the
first 4hoursoflife, or one that has not been on CMV
• Pro-Active-When an infantonCMVreaches a specific
thresholdand is then transitioned to HFOV
• Rescue-When an infanthasfailedallCMVstrategies and
continues to deteriorate,or who has developed airleakand is
then transitioned to HFOV

31. Δ

32. Decoupling of Ventilation and
Oxygenation
Controls for Oxygenation
• Paw
• FiO2
• Alveolar recruitment maneuver
Controls for Ventilation- takes time !
• Amplitude
• Hertz
• % I time

33. Tidal volume
• Lung compliance
• Resistance
• ET tube size
• Chest wall rigidity
affect
tidal volume

34. Clinical Strategy: Oxygenation (low lung
volumes)
• Begin with Paw 2-5 cm H2O > Paw on
CMV
• Increase MAP by 1 cm H2O until sats
stable
• Obtain CXR 30-60 min. later
• Optimal inflation: 8-9 ribs on CXR
• Wean MAP as compliance improves

35. Ventilation or CO2 removal
• Ventilation proportional to frequency times (amplitude)²
– Alveolar ventilation during CMV is defined as:
F x tft
– Alveolar Ventilation during HFV is defined as:
F x tft2
• Small change in amplitude makes a larger impact in CO2
• Frequency is usually kept constant hence CO2 changes depend on
amplitude
• Increasing amplitude reduces CO2

36. Setting up the ventilator
• MeanAirwayPressure– start with a MAP around 2-3
higher/lower than the MAP required during CMV
• Amplitude - start with twice the MAP or the sum of PIP
and PEEP is another option
• Frequency– 10 Hz in term babies and 12 Hz in preterms
• Inspiratorytime–33%

37. Respiratory System Impedance
• Respiratory system impedance (primarily the ETT) attenuates the HF
pressure waves
3.5 mm ETT ~ 80% of proximal ∆P islost
2.5 mm ETT ~ 90% of proximal ∆P islost
• Use the largest possible ETT Avoids leaks
Minimizes attenuation losses

38. CLINICAL APPLICATION:

39. • Hypoxia: • Increase MAP (Max 25 – 30)
• Increase FiO2
• Hyperoxia • Reduce FiO2
• Decrease MAP carefully
• Hypercapnia • Increase amplitude
• Decrease frequency
• Increase Ti
• Hypocapnia • Decrease amplitude
• Increase frequency

40. • Overinflation
• Reduce MAP
• Decrease frequency
• Hypotension
• Volume expansion in
hypotension
• Dopamine/Dobutamine
• Reduce MAP
• Discontinue HFO

41. MONITORING
• Sats
• ABG
• ET leak
• Chest wiggle- absent/diminished/
asymmetrical/check
• CXR
• Cranium USG

42. Weaning
• Once goals & adequate ventilation & oxygenation are achieved
– FiO2 < 30% gradually
– Decreased MAP to 6-8 cm of H2O
• Big Babies
– Extubate Directly from HFV
• Small Babies
– Switch over to CMV or CPAP

43. Failure of HFOV
• In babies with a lot of secretions needing frequent
suctioning
• Babies with a lot of spontaneous respiratory effort

44. COMPLICATIONS:

45. Evidence?

47. • There is no clear evidence that elective HFOV offers
important advantages over CV when used as the initial
ventilation strategy to treat preterm infants with acute
pulmonary dysfunction. There may be a small reduction in
the rate of CLD with HFOV use

49. HFJV vs HFOV:
• High frequency jet ventilation versus high frequency oscillatory
ventilation for pulmonary dysfunction in preterm infants
Cochrane database May 2016
• no evidence to support the superiority of HFJV or HFOV as elective or
rescue therapy

52. • In babies born at or near term (over 34 weeks gestation) who
have severe respiratory failure due to lung disease, there is no
evidence from randomized controlled trials to suggest that the
use of high frequency oscillatory ventilation is better than
conventional mechanical ventilation

53. Why the differences ?
• Different devices
• Severity of illness
• Timing of initiation of HFV
• Management strategy
• Duration of HFV
• Experience of clinicians

54. Which Ventilator is best?
• The tedious argument about the virtues of respirators not
invented over those readily available can be ended now
that it is abundantly clear that the success of such
apparatus depends on the skills with which it is used
Editorial in Lancet, 1965

55. Summary
◆ HFV is exciting & relatively new form of mechanical ventilation
for us
◆ HFOV has been linked to CPAP with wobbles
◆ It is superior to CMV in air leak syndromes
◆ CO2 should be monitored
◆ HFV: Not for all babies
◆ Appropriate use in appropriate condition at appropriate time in a
appropriate way

56. Not Machine but Man behind the
Machine- which is important !!!
Editorial in Lancet, 1965
THANK YOU..