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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.

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What is HFOV? Specific characteristics of HFOV

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  1. 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 characteristicsof 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. Patient / / HFO = HFJV = HFPPV 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; 100:1007-12

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

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

  7. HFO

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

  9. 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

  10. Adapted from Suzuki H Acta Pediatr Japan 1992; 34:494-500 From the lab to the bedside: The principal concepts

  11. Adapted from Suzuki H Acta Pediatr Japan 1992; 34:494-500 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

  12. Adapted from Suzuki H Acta Pediatr Japan 1992; 34:494-500 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

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

  14. Percentage airways with lesions 100 4+ 80 Epithelial injury 60 Hyaline Membranes 40 20 0 HFO-Hi HFO-Lo CMV The Open Lung Approach with HFOV (Lung-Lavaged Rabbits) McCulloch, Forkert, Froese ARRD 137:1185-1192,1988

  15. 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

  16. 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.

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

  18. 5 Hz versus 15 Hz: does it matter? Meyer J et al. PediatrRes 2006; 60: 401–406

  19. 5 Hz versus 15 Hz: does it matter? Meyer J et al. PediatrRes 2006; 60: 401–406

  20. 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)

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

  22. 100 90 80 70 60 50 40 30 20 10 0 0 5 10 15 20 25 30 35 pressure (cmH2O) How to set initial MAP when switching to HFOV 100 90 80 70 60 50 volume (ml) 40 30 20 10 0 0 5 10 15 20 25 30 35 pressure (cmH2O)

  23. Adapted from Suzuki H Acta Pediatr Japan 1992; 34:494-500 Recruitment concept during HFO And reduce FiO2!

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

  25. Adapted from Suzuki H Acta Pediatr Japan 1992; 34:494-500 Recruit first the lung and then keep open the lung at the lowest pressure necessary! 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!

  26. The clinical experience:HFO vs CMV

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

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

  29. Elective HFOV versus CMV CLD at 36-37 wks PMA or discharge Henderson-Smart DJ Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD000104. DOI: 10.1002/14651858.CD000104.pub2.

  30. Elective HFOV versus CMV CLD at 36-37 wks PMA or discharge 35% 39%  NNT 25 Henderson-Smart DJ Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD000104. DOI: 10.1002/14651858.CD000104.pub2.

  31. Elective HFOV versus CMV Combined Outcome: Death or CLD at 36-37 wks PMA or discharge Henderson-Smart DJ Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD000104. DOI: 10.1002/14651858.CD000104.pub2.

  32. 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

  33. MOAT II: Overall Survival HFOV CV N 75 73 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

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

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

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

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

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

  39. 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

  40. First Intention HFO with early lung volume recruitment Rimensberger PC et al. Pediatrics 2000; 105:1202-1208

  41. 30 300 250 25 200 20 15 150 100 10 50 5 0 0 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 time (h) time (h) 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 HFO HFO CMV CMV Rimensberger PC et al. Pediatrics 2000; 105:1202-1208

  42. days of ventilation 100 • HFO • CMV 80 60 p = 0.0004 40 20 0 0 20 40 60 80 100 120 140 days First Intention HFO with early lung volume recruitment oxygen dependency 100 • HFO • CMV 80 60 P < 0.0001 40 20 n=3 0 0 20 40 60 80 100 120 140 days Rimensberger PC et al. Pediatrics 2000; 105:1202-1208

  43. 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) 0.0004 * Oxygen dependency (days) 12 (4-17) 51 (20-60) <0.0001 * 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) 0.0006 # 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; 105:1202-1208

  44. 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

  45. 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 0 0 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 pressure (cmH2O) pressure (cmH2O) Rimensberger PC Intensive Care Med 2000; 26; 745-755

  46. 1. Similar effect on oxygenation 2. Similar protective effect on histology Rimensberger PC Intensive Care Med 2000; 26; 745-755

  47. Lung recruitment (open lung concept) during both, CMV and HFO reduces VILI in newborn piglets PPVOLC HFOOLC Lavaged PPVCON Van Kaam A Ped Research 2003

  48. Lung recruitment (open lung concept) during both, CMV and HFO reduces VILI in newborn piglets PPVcon PPVOLC HVOOLC Controls Van Kaam A Ped Research 2003

  49. 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

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

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