1. What is HFOV? Specific characteristics of HFOV
High frequency oscillatory ventilation (HFOV):
How does it work and how to integrate it in the concept of lung protective ventilation and of the open lung?
What is HFOV? Specific characteristics of HFOV
2) Basic mechanisms of gas exchange during HFOV
- How to set MAP when switching from CMV
- What are optimal settings and how to monitor
- Basic concepts of lung recruitment during HFO
3) How does HFOV fit in actual concepts of lung protection?

2. HFO = HFJV = HFPPV / /
Patient
Humidifed Bias Flow

3. “Elimination” of tidal ventilation
Slutsky AS ARRD 1988;138:175-83

4. Gas transport mechanisms during HFOV
Bouchut JC et al. Anesthesiology 2004; 100:

5. How Does HFOV Work Molecular Diffusion:
Is felt to be one of the major mechanisms for gas exchange in the alveolar regions.
It is responsible for the gas exchange across the AC
membrane and also contributes to the transport of O2 and CO2 in the gas phase near the membrane.
This may be due to the increased turbulence of molecules. 8

6. How Does HFOV Work Cardiogenic Mixing:
The heart beat adds to the the peripheral gas mixing. 7

7. Pressure transmission CMV / HFOV :
Tracheal pressure
Endinspiration
Endexpiration
Gerstman et al

8. CMV
HFO
PEEP 10, Vt 6
CDP 16
CMV
HFOV

9. HFO

10. Lung volumes
The Paw is used to inflate the lung and optimize the alveolar surface area for gas exchange.
Paw = Lung Volume

11. Oxygenation
Oxygenation is primarily controlled by the mean airway pressure (Paw) and the FiO2 for “Diffuse Alveolar Disease”.
The Paw is used to inflate the lung and optimize the alveolar surface area for gas exchange.
Paw = Lung Volume

12. From the lab to the bedside: The principal concepts
Adapted from Suzuki H Acta Pediatr Japan 1992; 34:

13. Lung Recruitment Using Oxygenation during Open
Lung High-Frequency Ventilation in Preterm Infants
Adapted from Suzuki H
Acta Pediatr Japan 1992;
34:
De Jaegere Ann et al. Am J Respir Crit Care Med 2006: 174; 639–645

14. Lung Recruitment Using Oxygenation during Open
Lung High-Frequency Ventilation in Preterm Infants
Adapted from Suzuki H
Acta Pediatr Japan 1992;
34:
De Jaegere Ann et al. Am J Respir Crit Care Med 2006: 174; 639–645

15. Lung Recruitment Using Oxygenation during Open
Lung High-Frequency Ventilation in Preterm Infants
before surfactant
after surfactant
De Jaegere Ann et al. AJRCCM 2006: 174; 639–645

16. The Open Lung Approach with HFOV
(Lung-Lavaged Rabbits) McCulloch, Forkert, Froese ARRD 137: ,1988 20 40 60 80
100
HFO-Hi
HFO-Lo
CMV
Percentage airways with lesions 4+
Epithelial
injury
Hyaline
Membranes 21 20

17. Ventilation
Ventilation is primarily determined by the stroke volume (Delta-P) or the frequency of the ventilator.
Alveolar ventilation during CMV is defined as:
F x Vt
Alveolar Ventilation during HFV is defined as:
F x Vt 2
Therefore, changes in volume delivery (as a function of pressure-amplitude, frequency, or % inspiratory time) have the most significant affect on CO2 elimination 10

18. Frequency controls the time allowed (distance) for the piston to move.
Therefore, the lower the frequency, the greater the volume displaced, and the higher the frequency, the smaller the volume displaced.

19. Theory of operation
Oxygenation and CO2 elimination have been demonstrated to be decoupled with HFOV

20. 5 Hz versus 15 Hz: does it matter?
Meyer J et al. PediatrRes 2006; 60: 401–406

21. 5 Hz versus 15 Hz: does it matter?
Meyer J et al. PediatrRes 2006; 60: 401–406

22. Mean airway pressure, amplitude and frequency
MAP (CDP): recruits alveoli/airways and maintains alveolar volume
 it is closely related to lung volumes and oxygenation
Amplitude: there is a close relationship between pressure amplitude and tidal volume
tidal volume depends on:
1) the volume displaced by the piston or diaphragm,
2) the resistance of the airways,
3) the compliance of the ventilator circuit, and
4) the patient’s lung mechanics
therefore: search for visible chest vibrations
change amplitude to control ventilation (PaCO2)

23. Bouchut JC et al. Anesthesiology 2004; 100:1007-12

24. How to set initial MAP when switching to HFOV

25. How to set initial MAP when switching to HFOV5 10 15 20 25 30 35
pressure (cmH2O) 40 50 60 70 80 90
100
100 90 80 70 60 50
volume (ml) 40 30 20 10 5 10 15 20 25 30 35
pressure (cmH2O)

26. Recruitment concept during HFO
Adapted from Suzuki H Acta Pediatr Japan 1992; 34:
And
reduce
FiO2!

27. A recruitment procedure in iRDS
Drop in SO2 10
Volume above FRC by respitrace 5 10 15 20 25 30 35
Airway pressures

28. Recruit first the lung and then keep open the lung at the lowest pressure necessary!
Adapted from Suzuki H
Acta Pediatr Japan 1992; 34:
Some bedside rules:
1) Lower FiO2 before CDP (=MAP)
2) Always try to define lung closing pressure to assure that you will use lowest pressures required
3) Try to work always the highest frequency possible - increase the amplitude in a first step to correct for high pCO2
4) If you’re “lost”
- always decrease CDP first!

29. The clinical experience: HFO vs CMV

30. Elective HFOV vs CMV: Death or CLD at 36 w GA or discharge
All trials
Favors HFO
Favors CMV
With volume recruitment

31. Cumulative Meta-Analysis: Incidence of CLD
Bollen et al. AJRCCM 2003; 168: 1150–1155

32. Thome UH Arch Dis Child Fetal Neonatal Ed 2005;90:F466–F473
Courtney
Johnson
Thome UH Arch Dis Child Fetal Neonatal Ed 2005;90:F466–F473

33.  The 2002 HFV Studies Johnson et al. N Eng J Med 2002;347:633-42
» HFOV vs. CMV in infants weeks
» SLE 2002, Dräger BabyLog, SensorMedics 3100
» Major findings:
- No difference in survival w/o BPD
- Less major intracranial abnormalities in the HFOV group
Courtney et al. N Eng J Med 2002 ;347:643-52
» HFOV vs. SIMV in infants gm
» Sensor Medics 3100
» Major findings:
- Infants randomized to HFOV were extubated earlier, received fewer days of postnatal steroids and were more likely to alive without CLD
- No difference in ICH or PVL

34. Why the differences? HFOV (n=232) 860 26.1 14% 30% 57% 22% SIMV
849
26.0
16%
37%
47%
23%
(n=400)
844
26.5
25%
41%
34%
CMV
(n=397)
863
26%
32%
19%
Mean BW (gm)
Mean GA (wks)
Mortality
36 weeks*
Alive w/o 36 wks
Severe IVH/PVL**
Why the differences?
- Different devices
- Severity of illness
- Timing of initiation of HFV
- Management strategy
- Duration of HFV
- Experience of clinicians

35.  The 2002 HFV Studies: 1) Different devices (?)
Johnson et al. N Eng J Med 2002;347:633-42
» HFOV vs. CMV in infants weeks
» SLE 2002 (48%), Dräger BabyLog (42 %), SensorMedics 3100 (10%)
» Major findings:
- No difference in survival w/o BPD
- Less major intracranial abnormalities in the HFOV group
Courtney et al. N Eng J Med 2002 ;347:643-52
» HFOV vs. SIMV in infants gm
» Sensor Medics 3100
» Major findings:
- Infants randomized to HFOV were extubated earlier, received fewer days of postnatal steroids and were more likely to alive without CLD
- No difference in ICH or PVL

36.  High lung volume strategy with HFOV
2) Management strategy ?
 High lung volume strategy with HFOV
(Lung-Lavaged Rabbits) McCulloch, Forkert, Froese ARRD 137: ,1988 20 40 60 80
100
HFO-Hi
HFO-Lo
CMV
Percentage airways with lesions 4+
Epithelial
injury
Hyaline
Membranes
PaO2/FiO2
MAP 21 20

37. HF(O)V vs CMV (not achieved) study protocol not followed !
2) Clearly defined HVS (FiO2, PaO2/FiO2) ?
HF(O)V vs CMV
Johnson et al.
MAP increased until FiO2 < 0.3
(not achieved)
study protocol
not followed !

38. HF(O)V vs CMV 2) Clearly defined HVS (FiO2, PaO2/FiO2) ?
Courtney et al.
MAP increased until FiO2 < 0.4
HFO: mean FiO to 0.41 over first 7 days
CMV: mean FiO to 0.36 over first 7 days p = 0.01
No differences in PaO2 between groups p = 0.62
(close to target range)

39. 3) Assigned ventilation mode until extubation ?
Johnson et al.
Median duration HFOV 3 days !!
Switched to CMV
Courtney et al.
Extubated from assigned mode

40. 4) How was the “control” group ventilated?
Johnson et al.
According the directions given by the attending physician
Starting ventilatory rate > 60/min
 pCO2 between mm Hg
Courtney et al.
Vt 5 to 6 ml/kg
Initial PEEP 4 to 6
(adequate inflation:
8th to 9th rib)
Mean FiO2: 0.3 to 0.36
Ventilatory rate < 60/min
 pCO2 > 40 mmHg

41. Cumulative Metaanalysis: HFV vs CMV
Ventilation strategies and outcome in randomised trials of HFV
Thome UH Arch Dis Child Fetal Neonatal Ed 2005;90:F466–F473

42. Are higher ventilatory rates (> 60/min) lung protective?
1) Heicher DA et al. Prospective clinical comparison of two methods for mechanical ventilation of neonates: Rapid rate and short inspiratory time versus slow rate and long inspiratory time. J Pediatr 1981; 98:957–961
2) Multicentre randomised controlled trial of high against low frequency positive pressure ventilation: Oxford Region Controlled Trial of Artificial Ventilation OCTAVE Study Group. Arch Dis Child 1991; 66:770–775
OCTAVE, 1990: no difference in duration of intubation or supplementary oxygen in survivors

43. Outcome in subgroups according ventilation strategies
HFOV vs. CMV: 36 weeks
Thome UH
Arch Dis Child Fetal Neonatal Ed
2005;90:F466–F473
HFOV vs. CMV: BPD or 36 weeks
HLVS high lung volume strategy;
CMV-strategy : low rate vs. high starting rate (< 60/min)
HLVS high lung volume strategy;
LPVS lung protective ventilatory strategy (?)
Bollen CW
AJRCCM 2003; 168:1150–1155

44. ? Outcome in subgroups according ventilation strategies
HFOV vs. CMV: 36 weeks
Thome UH
Arch Dis Child Fetal Neonatal Ed
2005;90:F466–F473
HFOV vs. CMV: BPD or 36 weeks
HLVS high lung volume strategy;
CMV-strategy : low rate vs. high starting rate (< 60/min) ?
HLVS high lung volume strategy;
LPVS lung protective ventilatory strategy (?)
Bollen CW
AJRCCM 2003; 168:1150–1155

45. Outcome in subgroups according ventilation strategies
HFOV vs. CMV: 36 weeks
Thome UH
Arch Dis Child Fetal Neonatal Ed
2005;90:F466–F473
HFOV vs. CMV: BPD or 36 weeks
HLVS high lung volume strategy;
CMV-strategy : low rate vs. high starting rate (< 60/min)
Low Vt, higher PEEP
Low Vt, higher PEEP …
according lung inflation and oxygenation
HLVS high lung volume strategy;
LPVS lung protective ventilatory strategy (?)
Bollen CW
AJRCCM 2003; 168:1150–1155

46. RCTs on lung-protective ventilation in newborn infants have mainly focused on comparing HFV with CMV, showing no clear benefits of HFV.
However, most of these RCTs had weaknesses in the design and, more importantly, in the ventilation strategy applied during both HFV and CMV.
Crit Care Med 2007

47. RCTs on lung-protective ventilation in newborn infants have mainly focused on comparing HFV with CMV, showing no clear benefits of HFV.
However, most of these RCTs had weaknesses in the design and, more importantly, in the ventilation strategy applied during both HFV and CMV.
But “To date, there are no neonatal RCTs explicitly evaluating low tidal volumes ... during CMV”.
Crit Care Med 2007

48. Elective HFOV versus CMV
CLD at wks PMA or discharge
Henderson-Smart DJ
Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD DOI: / CD pub2.

49. Elective HFOV versus CMV
CLD at wks PMA or discharge
Henderson-Smart DJ
Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD DOI: / CD pub2.
35% 39%  NNT 25

50. Elective HFOV versus CMV
Combined Outcome: Death or CLD at wks PMA or discharge
Henderson-Smart DJ
Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD DOI: / CD pub2.

51. HFOV compared with CMV for Diffuse Alveolar
Disease or Air Leak in Pediatrics
Arnold et al. Crit Care Med 1994;22
58 Children (29 CMV, 29 HFO)
Protocol: MAP was set 4-8 cm H2O > CMV-MAP
Decrease FiO2 before MAP
Results:
No difference in Death, Length of Vent., Air Leak.
Significant improvement in oxygenation with HFO over time.*
Less need for O2 at 30 days with HFO.* * p<0.05
HFOV is safe and improves oxygenation as well as outcome 24 23

52. MOAT II: Overall Survival
HFOV CV N
P/F 114 (37) 111 (42)
30d p=0.057
90d p=0.078
HFOV CV
Derdak S Am J Respir Crit Care Med 2002; 166:801–808

53. Predictors of Outcome 1) Oxygenation Index Response (OI = )
2) Entry Indicators of Compliance
(Peak Inspiratory Pressure)
MAP x FiO2 x 100
PaO2

54. MOAT II: Predictors of Outcome
Derdak S Am J Respir Crit Care Med 2002; 166:801–808

55. MOAT II: Survival - PIP  38 cmH20 (post-hoc)
30d p=0.019
90d p=0.026
HFOV CV
HFV-Meeting
2001

56. Early (< 24 h) versus late (>24 hours) intervention in pediatric ARDS
Fedora M Bratisl Lek Listy 2000; 101: 8-13

57. Metha S et al. Crit Care Med 2001; 29:1360 –1369

58. Time concepts for lung protection
Katzenstein AL et al. Surgical pathology of non-neoplastic lung disease. Saunders, Philadelphia, 1982
Neither a ventilation strategy nor a mode can repair the injured lungs 7 7

59. First Intention HFO with early lung volume recruitment
Rimensberger PC et al. Pediatrics 2000; 105:

60. First Intention HFO with early lung volume recruitment
Observational study, historical cohort: 71 premature infants with RDS at birth
Mean airway pressure
PaO2/FiO2 ratio 2 4 6 8 10 12 14 16 18 20 22 24 5 15 25 30
time (h) 2 4 6 8 10 12 14 16 18 20 22 24 50
100
150
200
250
300
time (h)
HFO
HFO
CMV
CMV
Rimensberger PC et al. Pediatrics 2000; 105:

61. First Intention HFO with early lung volume recruitment20 40 60 80
100
120
140
p =
days
days of ventilation
HFO
CMV
oxygen dependency
100
HFO
CMV 80 60 40
P < 20
n=3 20 40 60 80
100
120
140
days
Rimensberger PC et al. Pediatrics 2000; 105:

62. First Intention HFO with early lung volume recruitment
Survival and CLD Morbidity
all patients
HFO (n=32)
CMV (n=39)
p - value
survivors to 30 days
HFO (n=27)
CMV (n=35)
Ventilation (days)
5 (3-6)
14 (6-23) *
Oxygen dependency (days)
12 (4-17)
51 (20-60)
< *
Oxygen at 28 d, no (%)
6 (22)
22 (63)
0.002 #
survivors to 36 weeks PCA
HFO (n=27)
CMV (n=34)
CLD; Oxygen > 36 weeks PCA, no (%)
0 (0)
12 (35) #
Values are given as the median (95% CI) or the number (percentage) of patients; * Mantel-Cox log-rank; # Fisher's exact
Rimensberger PC et al. Pediatrics 2000; 105:

63. Recruitment bei der Hyalinen Membranenkrankheit (RDS)
28 wks GA, 8 hours after birth, on HFOV, no surfactant received
MAP 26 cmH2O
Stepwise increase of MAP
Stepwise decrease of MAP
MAP 12 cmH2O, Amplitude 40, FiO2 0.8
MAP 16 cmH2O, Amplitude 28, FiO2 0.21
08’10
08’25

64. Recruitment during both, HFO and CMV, follows similar concepts when using small tidal volume ventilation
100
100 90 90 80 80
HFO after
recruitment
CMV after
recruitment 70 70 60 60 50 50
volume (ml) 40 40 30 30 20 20 10 10 5 10 15 20 25 30 35 5 10 15 20 25 30 35
pressure (cmH2O)
pressure (cmH2O)
Rimensberger PC Intensive Care Med 2000; 26;

65. 1. Similar effect on oxygenation
2. Similar protective effect on histology
We could show an identical effect on oxygenation and both methods were equipotent in attenuating ventilator induced lung injury.
Rimensberger PC Intensive Care Med 2000; 26;

66. Lung recruitment (open lung concept) during both, CMV and HFO reduces VILI in newborn piglets
Lavaged
PPVOLC
HFOOLC
PPVCON
Our finding have been confirmed also in the newborn lung injury model by Anton van Kaam in Amsterdam. He compared conventional mechanical ventilation with an open lung approach during CMV and HFO and could show identical results for the two strategies that used a recruitment approach.
Van Kaam A Ped Research 2003

67. Lung recruitment (open lung concept) during both, CMV and HFO reduces VILI in newborn piglets
PPVcon
PPVOLC
HVOOLC
Controls
Our finding have been confirmed also in the newborn lung injury model by Anton van Kaam in Amsterdam. He compared conventional mechanical ventilation with an open lung approach during CMV and HFO and could show identical results for the two strategies that used a recruitment approach.
Van Kaam A Ped Research 2003

68. OLV improves gas exchange and attenuates secondary lung injury in a piglet model of meconium aspiration
pO2
pCO2
Van Kaam A et al. Crit Care Med 2004; 32:443–449

69. Saline
OLV improves gas exchange and attenuates secondary lung injury in a piglet model of meconium aspiration
PPVcon
PPVOLC
Van Kaam A et al. Crit Care Med 2004; 32:443–449

70. OLC in a neonatal piglet lavage model
Van Kaam A Biol Neonate 2003;83:273-80

71. Standardized volume recruitment during:
SIMV vs
PSV vs
HFOV
Krishnan RKM Intensive Care Med 2004; 30:1195–1203

72. Recruitment and the Open Lung Concept is all about avoiding collapse and overdistention

73. Recruitment and the Open Lung Concept during HFOV is all about keeping the lung open at the least pressure cost

74. (surfactant depleted lung)
The difficulty to place the ventilatory cycle within the safe window during CMV when compared to HFOV
Airway pressure (cmH2O)
Volume (l)
(surfactant depleted lung)
ALI
severe
(A)RDS
Adapted from Suzuki H
Acta Pediatr Japan 1992; 34:

75. Time constant: T = Crs x Rrs
Hickling KG et al. AJRCCM 2001; 163:69-78
Adapted from Suzuki H
Acta Pediatr Japan 1992; 34:
“The beauty of simplicity”
HFOV: Turn 1 knob …
and observe 2 parameters (O2, CO2)
CMV: chose your allowable Vt
Turn then 1 (or 2 knobs) …
and observe 3 parameters
(O2, CO2, Cdyn)
Time constant: T = Crs x Rrs
and remember to adapt Ti and Te

77. Lung Recruitment Using Oxygenation during Open
Lung High-Frequency Ventilation in Preterm Infants
De Jaegere Ann et al. Am J Respir Crit Care Med 2006: 174; 639–645

78. The myths about HFOV

79. The myths about HFOV Failure Criteria
Inability to decrease FiO2 by 10% within the first 24 hrs.
Inability to improve ventilation or maintain ventilation (after optimizing both frequency and amplitude) with PaCO2 < 80 with pH > 7.25.

80. The myths about HFOV Hemodynamics Yes, but…
Maintain a normal Mean Arterial Pressure!
Initially increase CVP to mmHg by giving volume (colloid or crystalloid).
If PCWP < 15, continue volume. If PCWP is unavailable and CVP is 15-20, institute vasopressors.
Yes, but…
Make sure that you can not lower Paw!!!!

81. Continuous blood gas monitoring during HFO
CDP: 13 12 11 10 9 11
Overdistention
Collapse

82. The myths about HFOV Patients will need heavy sedation and
ev. even paralysis during HFOV!
Not as pragmatic!
Try to let them breath spontaneously
during HFOV if any possible
HFOV can be seen as a Super-CPAP

83. Derdak Crit Care Med 2003; 31[Suppl.]:S317–S323

84. Imposed WOBi during spontaneous breathing on HFOV
Van Heerde M et al. Critical Care 2006, 10:R23

85. Imposed WOBi during spontaneous breathing on HFOV
Critical Care 2006, 10:R23
Critical Care 2006, 10:R23
Critical Care 2006, 10:R23
Van Heerde M et al.
Critical Care 2006, 10:R23

86. Spontaneous breathing during HFOV
Increased imposed work of breathing !

87. Demand-flow System during HFOV
allows to unload WOBi
physiologic WOBi: 0.5 J/L
Van Heerde M et al. Critical Care 2006, 10:R103

88. HFOV
Fits well in the concept of lung protective ventilation strategies – when used early in the course of disease
Allows to maintain better physiologic blood gas values and acid-base balance
Allows, especially in small children to maintain spontaneous ventilation
Is simple to use once you get familiar with it
But has not really proven to be better than CMV in the clinical set-up

89. Continuous blood gas monitoring during HFO
CDP: 13 12 11 10 9 11
Overdistention
Collapse