High-frequency oscillatory ventilation (HFOV) is proposed as a strategy to prevent ventilator-induced lung injury (VILI) in patients with acute respiratory distress syndrome (ARDS), with evidence indicating it may improve oxygenation and reduce mortality. The document discusses the implementation of HFOV, including candidate selection, timing, and techniques for recruitment, while emphasizing the importance of minimizing tidal volume and managing oxygenation. Further research is needed to fully understand HFOV's benefits and outcomes compared to conventional ventilation methods.

1. High-Frequency Oscillation:
New Directions for 2009
Niall D. Ferguson, MD, FRCPC, MSc
Assistant Professor
Interdepartmental Division of Critical Care Medicine
University of Toronto

2. HFO:
A Canadian
Invention

3. Outline
• Background on HFO
• Ventilator-induced Lung Injury (VILI)
• Implementing HFO to prevent VILI
 Who
 When
 How
 Oxygenation & Recruitment
 Ventilation
 Transition back to CV

4. Pressure-Time Curve
CMV
HFOV
P
r
e
s
s
u
r
e
Time

5. Patient
HFOV Gas-flow Circuit
Humidified Bias Flow
Active Expiration R
Humidifier

6. HFOV - Setup
Settings
• PAW
• P (Power)
• Frequency
• Bias Flow, I:E

8. In Adults – HFOV is safe & improves
oxygenation - appropriate as
rescue therapy

9. High-frequency oscillatory ventilation for adult
respiratory distress syndrome: Let's get it right this
time! AB Froese Crit Care Med 1997; 25:906-908

10. ARDS Network
• High Stretch
 VT: 11.8
 PPLAT: 32-34
 RR: 18
 VMIN: 13
 PEEP: 8
• Mortality 40%
• Low Stretch
 VT: 6.2 ml/kg
 PPLAT: 25 cm H2O
 RR: 29
 VMIN: 13 L/min
 PEEP: 9 cm H2O
• Mortality 31%*
*p=0.005
N Engl J Med 2000 342:1301-8

12. Can We Reduce VILI
any Further?

13. Preventing VILI - Principles
• Limit overdistention
• Maintain EELV
• Minimize oxygen toxicity
• HFOV benefits:
 margin of error for overdistention /
derecruitment
- Decoupling of ventilation & oxygenation
- Improved oxygenation  FIO2
Employ early

14. Alveolar (In)stability
JM Steinberg et al. AJRCCM 2004; 169:57-63 DiRocco, Nieman AARC 2005

15. 14/0 45/0
Experimental pulmonary edema due to intermittent positive pressure ventilation
with high inflation pressures. Protection by positive
end-expiratory pressure. HH Webb & DF Tierney ARRD 1974; 110:556-65

16. 14/0 45/10 45/0
Experimental pulmonary edema due to intermittent positive pressure ventilation
with high inflation pressures. Protection by positive
end-expiratory pressure. HH Webb & DF Tierney ARRD 1974; 110:556-65

17. HFO vs. Injurious CV in Animals

18. HFO vs. ‘protective’ CV in animals

19. Outcomes
30 Day Mortality
HFOV: 37%
CMV: 52%
Absolute Risk Reduction: 15%
Relative Risk Reduction: 29%
p=0.102
p=0.057 30 d
p=0.078 90 d
HFOV in adults with ARDS is safe and may
improve outcome – more study is needed

20. HFO

22. Background
 HFO is theoretically ideal for lung protection
 early RCTs suggest HFO is safe and may reduce deaths
Design
 multicentre RCT
Population
 72 patients with ARDS, at 12 participating sites
Interventions
 HFO
 conventional ventilation - a low tidal volume, open lung approach
Primary outcome
 hospital mortality
Pilot study goals
 assess recruitment, and barriers to recruitment
 assess adherence to explicit ventilation protocols
 measure and understand reasons for crossovers

23. Outline
• Ventilator-induced Lung Injury (VILI)
• Background on HFO
• Implementing HFO
 Who
 When
 How
 Oxygenation & Recruitment
 Ventilation
 Transition back to CV

24. HFOV compared with CMV for Respiratory
Failure in Preterm Infants HIFI Group N Engl J Med 1989;320
673 preterms with respiratory failure within 12 hrs of CMV
346 CMV, 327 HFOV
HFOV - MAP as with CMV, FiO2 was increased first
Results:
Similar Bronchopulmonary Dysplasia & Mortality
Increased pneumoperitoneum, intracranial bleeds,
periventricular leukomalacia

25. Reflections on HIFI
Bryan & Froese Pediatrics 1991;87
1. Goals were not to increase lung volume.
2. PAW weaned before FiO2.
3. Cross centre differences in adverse events.

27. Volume-Pressure Curve
CMV
HFO
V
o
l
u
m
e
Pressure
Lower
Inflection
Point
Upper
Infection
Point

28. RMs with Conventional Ventilation
• Multiple studies – inconsistent results
 Timing
 Type of manoeuvre
 Cause of lung injury
 How PEEP was set afterwards
• With HFO
 Theoretically RMs may be of more use (because
of lack of tidal recruitment)
 and may be more effective (because of ability to
set a very high PEEP)

29. PaO2
Time (min.)
HFO - Recruitment Manoeuvres
• Oleic Acid Lavaged
Rabbits
• Conventional
Ventilation followed
by HFOV
 With and without
Sustained Inflation
(30 cm H2O for 10 s)
Relationship Between
PaO2 and Lung Volume
During HFOV
Suzuki et al. Acta Pedr Jpn 1992

31. > 0.6

32. 0
100
200
300
400
Standardized CMV HFOV + 1-3 RMs
(1.5 Hours)
PaO2/FIO2
Individual & Mean PaO2/FIO2 Values

34. HFO
Prone

35. Conclusions
• HFO theoretically ideal for preventing VILI –
if used with a strategy to maintain EELV
• On balance the potential for benefit with RMs
in HFO seems to outweigh downsides
• Lung recruitment is a good thing - If it can be
achieved
 Ineffective attempts at lung recruitment:
no benefit vs. harmful

36. Outline
• Ventilator-induced Lung Injury (VILI)
• Background on HFO
• Implementing HFO
 Who
 When
 How
 Oxygenation & Recruitment
 Ventilation
 Transition back to CV

37. High-frequency oscillatory ventilation for adult
respiratory distress syndrome: Let's get it right this
time! AB Froese Crit Care Med 1997; 25:906-908

38. HFOV - background
• Respiratory frequencies 180-900 / min
• Tidal volumes (VT) < dead space (VD)
• Ventilation (CO2) dependent on:
 VT  P frequency
• Oxygenation dependent on:
 PAW / lung volume
 FIO2
Decoupling
of O2 / CO2

39. Slutsky & Drazen NEJM 2002, 347:630-1

40. Crit Care Med 2003; 31:227-231
< 1.2 - 2 ml/kg ?

41. Crit Care Med 2006; 34:751-757
Hot-wire Anemometer

44. Conclusions
• In addition to targeting lung
recruitment we need to deliver the
lowest VT possible
 Higher frequencies (facilitated by higher
power / delta P)
 Controlled cuff leak?
 Accept a ‘reasonable’ pH

45. Outline
• Ventilator-induced Lung Injury (VILI)
• Background on HFO
• Implementing HFO
 Who
 When
 How
 Oxygenation & Recruitment
 Ventilation
 Transition back to CV

46. Implementing HFO 2009
• Who should we consider as candidates for
HFO?
 Sick ARDS patients in need of recruitment
• When should we use HFO?
 Rescue therapy for now
 Maybe earlier rather than later
• How we use HFO?
 Oxygenation = Target lung recruitment
 Ventilation = Keep tidal volume minimal

48. HFO

49. n.ferguson@utoronto.ca
October 25 – 29, 2009
Metro Toronto Convention Centre

50. n.ferguson@utoronto.ca