Introduction. Indication and Exclusion Criteria. Technical Aspects. Initial Controls and Settings. Monitoring, Assessment, & Adjustment. Maintaining ABG Goals. Returning to Conventional Ventilation. Troubleshooting.

1. Ahmed Al Gahtani, BSRC, RRT
Principal Respiratory Therapist
Critical Care Senior Respiratory
Therapist

2. • Introduction.
• Indication and Exclusion Criteria.
• Technical Aspects.
• Initial Controls and Settings.
• Monitoring, Assessment, & Adjustment.
• Maintaining ABG Goals.
• Returning to Conventional Ventilation.
• Troubleshooting.

3. What is HFOV?
• HFOV provides small tidal volumes (not really a tidal
volume, but an Amplitude, usually referred to as Delta
P: P) usually equal to, or less than, the dead space;
150 millilitres, at a very fast rate (Hertz-Hz) of
between 4-5 breaths per second.
• The delivery of tidal volumes of dead space or less at
very high frequencies enables the maintenance of a
minute volume.
• Lungs are kept open to a constant airway pressure via
a mean pressure adjust system.
• HFOV allows for the decoupling of oxygenation from
ventilation: it allows the clinician to separately adjust
either oxygenation or ventilation.

4. Why Should we use HFOV?

5. Pressure-Volume Loop
Volume
Pressure
Inspiration
“Beaking” with
overdistension
Expiration
Atelectasis
Zones of Injury
Froese, CCM, 1997

6. Open Lung Ventilation Strategy
Volume
Pressure
Zone of Overdistention
Safe
window
Zone of
Derecruitment
and
atelectasis
Goal is to avoid injury zones
and operate in the safe window
Froese, CCM, 1997

7. INJURY
INJURY
CMV
HFOV
• During CMV, there are swings between the zones of
injury from inspiration to expiration.
• During HFOV, the entire cycle operates in the “safe
window” and avoids the injury zones.

8. Ventilator Induced Lung Injury
Volutrauma
Caused by high lung volume
Barotrauma
Caused by excess airway pressure
Atelectotrauma
Caused by repetitive closing/opening of collapsed
alveoli
Biotrauma
Caused by mechanical stresses which triggers the
inflammatory cytokine cascade  Organ Faulire

9. So What??
Reduce the
Risk of VILI
Allows
Recruitment of
Alveolar Space
Improves V/Q
Matching
Decoupling of
Oxygenation
from
Ventilation
Safer
Mode of
Ventilation for
Patients with
Decreased Lung
Compliance

10. Comparison
Ventilator Rate Volume
Conventional Ventilator 1 to 120 4 to 20 cc/kg
Sensor Medics 3100B 60 to 900 0.1 to 1.5 cc/kg
Conventional Ventilator: active
inspiration with passive
expiration
HFOV: active inspiration with
active expiration

11. How does it do that?
HFOV provides small tidal volumes
(not really a tidal volume, but an Amplitude, usually
referred to as Delta P
usually equal to, or less than, the dead space; 150
ml
at a very fast rate of between 180-900 breaths per
minute
3 – 15 Hz

12. How does it do that?
Convection (bulk flow) ventilation
Asymmetrical velocity profile
Taylor dispersion
Molecular diffusion
Pendelluft
Cardiogenic mixing

13. How does it do that?
HFOV keeps the lungs/alveoli open at a constant,
less variable, airway pressure
This prevents the “inflate/deflate, inflate/deflate”
cycle, which has been shown to damage alveoli and
further complicate lung disease

14. How does it do that?
Further, HFOV allows for the decoupling of
oxygenation from ventilation:
It allows the clinician to separately adjust either
oxygenation or ventilation
It is believed that HFOV may enhance gas mixing
and improve V/Q matching

17. How does the machine ventilate the
patient?
Follow ME to
The Machine


18. Inadequate oxygenation/CO2
elimination that cannot safely
be treated without potentially
toxic ventilator settings and,
thus, increased risk of
ventilator Induced lung injury
(VILI)
ARDS
Air Leak
Syndrome
Broncho-Pleural
Fistula

19. Asthma
IPF
Idiopathic
pulmonary
fibrosis
COPD

20. Hertz = BPM
Power
(Amplitude ∆
P)
Bias FlowFiO2
mPaw
Inspiratory
time %
25 – 40
LPM
100%
5 above
mPaw on
CMV
Power 4
Amp 45 –
55
cmH2O
Hz 5 to 6 33%
Oxygenatio
n Ventilation Constant

21. • Resuscitation bag with PEEP valve attached to an O2
source
• Airway is suctioned and patent before starting HFOV
• Adequate titration of sedation and analgesia
• Initiation of neuromuscular blockade (Don’t forget the
train of four)
• Make sure patient is well hydrated and normotensive.
• Starting of HFOV may induce hypotension; volume
expanders and inotropic support should be available

22. • Set Bias Flow at 25 - 40 LPM.
• Set Amplitude 45 – 60 cm H2O (Power of 4.0) and increased it to
achieve chest wiggle down to the level of the groin (mid-thigh).
• Inspiratory time percent (It %) is started at 33%.
• Frequency starts at 5 Hertz (Hz) . Watch pH if low (< 7.2) you may
set it at 4 Hertz.
• Set Mean Paw at 5 cm H2O above patient’s Mean Paw on CMV.
• Set FiO2 at 100 %
• Set high pressure alarm at 5 cm H2O above mean Paw, and low
pressure alarm at 5 cm H2O below mean Paw.

23. • ABG should be obtained within 30 to 60 mins post-HFOV
initiating.
• CXR 1 to 4 hours post-HFOV initiating, (ordered).
Achieving optimal lung volume: (assess
initial CXR)
CXR showed good lung expansion to the level of T8 –
T9 posterior, if not increase mean Paw by increments
of 1 to 2 cm H2O. ( To maximum of 35 H2O)

24. • Hypercapnia / Respiratory Acidosis:
Increase the amplitude by 5 cm H2O to maximum
Amp =(3 X mean Paw) not to exceed 100 cm H2O.
Decrease Hz by 1 to minimum of 3 Hz.
Generate ETT leak.
Creating a Cuff Leak
The Cuff Leak is indicated for high PaCO2 with no response
to Amp and Hz. (Amp ≥ 100 cmH2O and Hz ≤ 3.5) and with
optimal mPwa.
1. Assess the patency of the EET, suction the tube.
2. Assess appropriate lung volumes.
3. If both 1 and 2 are fine, then proceed with the procedure.
4. Withdraw air from the cuff with a syringe to create a drop
of 5 cmH2O in the mPaw.
5. Increase the bias flow to adjust the mPaw to the set level.

25. • Hypocapnia / Respiratory Alkalosis
Decrease amplitude by increments of 5 cm H2O to the
minimum amplitude that gives adequate chest wiggle.
Increase the frequency by 1 to achieve 5 to 6 Hz.
Allow 30 minutes between
changes – use ABGs to
guide

26. • Worsening Oxygenation
Increase FiO2 by 5% as needed to FiO2 of 100%.
Increase mean Paw by 2 cm H2O as needed to
maximum of 35 cm H2O.
Consider Recruitment Manoveuver.
Recruitment Maneuver
RMs is indicated at commencement of HFOV and if SpO2
decreases > 5% with suctioning, positioning, or any other
procedure.
Before the RM:
• To be conducted only after assessment of adequacy of
cardiovascular function and volume status. (Patient is
hemodynamically stable)
• ICU Consultant or Registrar must be in attendance during
procedure.
RM Procedure
1. Set high airway pressure alarm to 50 cmH2O.
2. Inflate cuff to occlude leak. (if cuff was deflated to establish a
leak to acceptable cuff pressure 22 – 28 cm H2O )
3. Set HFOV to standby (Stop the piston).
4. Increase mPaw to 40 – 45 cmH2O for 40 – 60 secs (watch BP
and decrease mPaw immediately if MAP < 60 mmHg or fall
more than 20 mmHg).
5. Return mPaw to previous setting.
6. Reset cuff leak.
7. Restart piston.

27. If increased PaCO2 with pH
< 7.2 despite maximum ΔP,
frequency of 3 Hz, and cuff
leak. (ensure ETT patency)
or/and failure to wean FiO2
to ≤ 60% within 24 hours.
Then Consider inhaled nitric
oxide and/or prone position
Return to
conventiona
l

28. • Consider trial of CV when FiO2 ≤ 40% and mPaw < 22
cmH2O
• Set up conventional ventilator / standby
• Set ventilator on PCV, PC 20cm H2O (to achieve Vt of
approx 6 mL/Kg), PEEP 10 to 15 cm H2O (to achieve
mean Paw 20 cm H2O +/- 2), FiO2 5% > HFOV setting,
RR 15 to 20 BPM, I:E ratio 1:1 to 1:3 (Ti 0.85 t0 1.2 sec).
• ABGs in 30 mins – reassess settings.
• Consider Recruitment Manoveuvre (RM).
Allow 30 minutes between
changes – use ABGs to
guide

29. • Vital Signs (BP, HR, MAP, SpO2)
• Chest Wiggle
• ABG/VBG
• CXR
• Secretion
• Airway Patency
• Equipment
• Patient ??????????

30. • Chest “wiggle” factor–assess initially and routinely,
especially after any major re-positioning
• Auscultate the intensity of oscillation– must be equal
throughout chest
• ET tube position should be checked regularly
• Recognize the bad signs! - ↓chest wiggle, ↓ BP, ↓
SaO2

31. • Continuously assess chest vibration(chest wiggle factor)
o CWF depends on the amount of amplitude and lung
compliance
o Vibrations should be equal and continuous
o Visual assessment of the depth of wiggle :
 Neonates from nipple line to umbilicus
 Pediatrics from clavicle to hips
 Adults from clavicles to mid thigh

32. • Chest wiggle factor: Absent or diminished
• Clinical sign for airway obstruction/ETT displacement
(notify RCP re; suctioning, increase power)
• If CWF present on one side suspect pneumothorax or
ETT has slipped down a bronchus
( check position of ETT, obtain CXR)

33. • Evaluation of chest expansion on CXR(T8-9)
• Check capillary refill, skin color , temperature
• Compare central with peripheral pulses
• Pulse oximeter: continuous non-invasive monitoring
• Blood Pressure
• Do not disconnect tubing during repositioning
(risk of alveolar collapse , loss of lung volume)
• After change of position check for chest wiggle, SpO2,
ETT placement

34. • When repositioning: minimum of two people ( nurse & RT)
• Do not suction for the first 24 unless necessary
• Suction using the clamp technique or use an in-line suction
catheter
• Obtain blood gas and CXR within the first hour of initiation
• Reposition carefully, ensure a smooth interface (free of kinks)
between ET tube and oscillator circuit
• Document: Amp, FiO2, Map, and Hz, and auscultation
assessment

35. • Lung Overdistension
• Pneumothorax
• ET Tube obstruction (caused by secretions)
• Tracheal inflammation and necrotizing tracheobronchitis
(oscillator circuit needs adequate humidification)
• Decreased cardiac output ( due to increased thoracic
pressure)