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High Frequency Oscillatory

High Frequency Oscillatory. Nir Hus MD., PhD. Ryder Trauma Center Jackson Memorial Hospital 2010. High Frequency Ventilation. Defined by FDA as a ventilator that delivers more than 150 breaths/min. Delivers a small tidal volume, usually less than or equal to anatomical dead space volume.

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High Frequency Oscillatory

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  1. High Frequency Oscillatory Nir Hus MD., PhD. Ryder Trauma Center Jackson Memorial Hospital 2010 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  2. High Frequency Ventilation • Defined by FDA as a ventilator that delivers more than 150 breaths/min. • Delivers a small tidal volume, usually less than or equal to anatomical dead space volume. • While HFV’s are frequently described by their delivery method, they are usually classified by their exhalation mechanism (active or passive). Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  3. Adult High Frequency Jet Ventilation • First reports 1977 (Klain and Smith) • First Randomized Controlled Trial 1983 • Carlon (Sloan Kettering Hospital, NY) • 300 patients with ARDS • Outcome reported no difference to CMV • Methodology limitations on jet ventilation • First commercially sponsored study 1993 • APT1010 (Infrasonics 1010) • Rescue of 90 patients with ARDS (non R.C.T.) • Improved survival as compared to historic controls by expected mortality. Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  4. First used in neonatal ICU’s since late 1980’s • High frequency ventilators with power to oscillate an adult became available in the mid 1990’s • Currently used as a rescue therapy in adults unable to be managed with CMV • HFOV is safe and effective in improving oxygenation while minimizing alveolar over-distention • One of the main challenges is weaning back to CMV. Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  5. Jet Ventilators Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  6. Piston - Diaphragm Oscillators Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  7. Membrane oscillates at 3 to 15/sec. • Delivers tidal volume 1 to 5 ml/kg. • Allows almost complete separation of the functions of oxygenation and ventilation. • Active inspiratory and expiratory phases. Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  8. Rationale for HFOV • Small VT results in a minimal variation around PAW and mean lung volume during tidal breathing • PAW can be adjusted to avoid areas of atelectasis and over-distention (barotrauma) Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  9. Oxygenation in HFOV • Oxygenation is proportional to the mean airway pressure (PAW) and resultant lung volume • PAW influenced by the rate of bias flow and changes in the resistance valve Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  10. Ventilation (CO2 Removal) in HFOV • Ventilation is controlled by pressure amplitude of the oscillating membrane and the respiratory frequency • CO2 removal is improved by increase in pressure amplitude but decreased by increases in frequency • VT and frequency are related inversely, therefore HFOV VT has a dominant effect Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  11. Mechanisms of HFOV Gas Exchange • There are six mechanisms of gas exchange during HFOV • Convective Ventilation • Asymmetrical Velocity Profiles • Taylor Dispersion • Pendeluft • Molecular Diffusion • Cardiogenic Mixing Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  12. Proximal and Alveolar Pressures HFOV vs. CMV Gerstmann D. Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  13. Why High Frequency Oscillatory Ventilation? Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  14. ARDS Pulmonary Injury Sequence • Phase 1 Early Exudative Process • Endo/Epithelial Damage • Type 1 Alveolar Cell Injury • Capillary Congestion • Interstitial/Alveolar Edema, Hemorrhage • Protein Accumulation • Surfactant Deactivation • Atelectasis • Hyaline Membrane Formation • Inflammatory Cell Migration • Volutrauma - Increased Protein Leak, Atelectasis, etc. Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  15. ARDS Pulmonary Injury Sequence • Phase 2 Proliferative (Day 5-10) • Proliferation of Type 2 Cells • Fibroblast Migration • Interstitial Collagen Formation • Increased Dead Space • Decreased Compliance • Increased Pulmonary Vascular Resistance Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  16. ARDS Pulmonary Injury Sequence • Phase 3 Fibrotic (Day 10-14) • Lung Destruction • Emphysematous Changes • Fibrosis • Pulmonary Vascular Obliteration • Chronic Lung Disease Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  17. Ventilator Induced Lung Injury Rodents ventilated with three modes: • High Pressure (45 cmH2O), High Volume • Low Pressure (negative pressure ventilator), High Volume • High Pressure (45 cmH2O), Low Volume (strapped chest and abdomen) Dreyfuss,D ARRD 1988;137:1159 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  18. Ventilator Induced Lung Injury • Stretch Injury • Alters capillary transmural pressures • Relaxation changes in transmural pressure causes breaks in capillary endo and epithelium • Increases leak of proteinacious material • Promotes Atelectasis Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  19. Capillary Leak Fu Z, JAP 1992; 73:123 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  20. Ventilator Induced Lung Injury Premature baboon model Coalson J. Univ Texas San Antonio Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  21. Ventilator Induced Lung Injury Premature baboon model Coalson J. Univ Texas San Antonio Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  22. Ventilator Induced Lung Injury • ARDS • Atelectasis • Over-distended airways and alveoli • Cellular accumulation • Hyaline Membranes Lamy ARRD 1976; 114:267 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  23. Ventilator Induced Lung Injury • ARDS late stage structural changes • Enlarged air space • Septal destruction • Fibrotic lesions Rouby JJ, Inten Care Med 1993; 19:383 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  24. Pediatric Randomized Controlled Trial Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  25. Pediatric Randomized Controlled Trial 3100A HFOV 29 patients 11 failures (82% died on CMV) 83% HFOV survivors had normal lung function Conventional Ventilation 29 patients 19 failures (HFOV Saved 58%) 30% CMV survivors had normal lung function Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  26. Pediatric Randomized Controlled Trial Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  27. 3100B Pilot Trial Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  28. 3100B Rescue Trial • Fort P, et al. High-frequency oscillatory ventilation for adult respiratory distress syndrome-a pilot study. Crit Care Med 1997; 25:937-947 • Seventeen patients failing inverse ratio ventilation recruited for rescue with HFOV (3100B) • Projected mortality > 80 percent Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  29. 3100B Rescue Trial Fort P, Crit Care Med 1997; 25:937 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  30. 3100B Rescue Trial Fort P, Crit Care Med 1997; 25:937 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  31. 3100B Rescue Trial Oxygenation Index and P/F ratio in first 48 hours of HFOV Survivors versus non-survivors Fort P, Crit Care Med 1997; 25:937 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  32. 3100B Rescue Trial Fort P, Crit Care Med 1997; 25:937 Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  33. 3100B Rescue Trial Summary • Seventy-six percent (13/17) improved their oxygenation as indicated by improvements in P/F ratio (p<0.02), Oxygenation Index (p < 0.01) and change in FiO2 (p < 0.02). • Forty-seven percent (8/17) weaned back to conventional ventilation. • Thirty day mortality was 53% Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  34. 3100B Rescue Trial Summary • Overall respiratory deaths were 33% • There were no signs of change in cardiac output with use of high mean airway pressures • More days of CMV prior to HFOV resulted in increased mortality (p < 0.009) • Similar to the pediatric RCT, failure to respond to HFOV was highly specific for death Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  35. MOAT II Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  36. Multicenter Oscillator ARDS Trial(MOAT2) • Prospective Randomized Controlled Trial of the SensorMedics 3100B High Frequency Oscillatory Ventilator for adults with ARDS • Follow-up to MOAT Pilot Rescue Trial • Early Entry, Non-Crossover Trial • Eight Institutions, North American Study Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  37. Multicenter Oscillator ARDS Trial(MOAT2) • Inclusions: • Age 16 years and • Weight 35 kg and • P/F ratio < 200 (with PEEP 10 cm H2O or greater) • on two consecutive ABG’s > 30 min. apart but <4 hrs apart with • bilateral infiltrates and • PA wedge < 18 mmHg or • no evidence of LA hypertension and • ability to gain Informed Consent (surrogate) Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  38. Multicenter Oscillator ARDS Trial(MOAT2) • Exclusions: • FiO2> 80% for 48 hrs • Air Leak grade 3 or 4 • Non-pulmonary terminal prognosis • Intractable shock (see below) • other experimental Rx for ARDS or Sepsis > 30 days • Severe COPD or Asthma Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  39. Multicenter Oscillator ARDS Trial(MOAT2) • Initial HFOV Strategy: • mean Paw set 5 cmH2O > CMV setting • set rate 5 Hz, 33% I-time • set Amp. for adequate chest wiggle Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  40. Study Population Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  41. Study Population Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  42. Study Population Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  43. Study Population Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  44. Outcomes Note: Of the HFOV patients requiring respiratory support at 30 days, 61% required mechanical ventilation. Seventy percent (73s%) of the CMV patients required mechanical ventilation. The balance of patients were on oxygen only. Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  45. 30 Day Mortality Outcomes Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  46. TV/kg IBW Mortality N Mean TV < 8 ml/kg 67% 6 7.13 8-10 ml/kg 44% 25 9.15 > 10 ml/kg 46% 28 11.54 Predictors of CMV Outcomeby Tidal Volume – Ideal Body Weight Based on the NIH ARDSnet data, an analysis of mortality in the CMV group found that there appeared to be no relationship between tidal volume per kg ideal body weight in the control group and mortality and that other factors may have influenced the outcome. Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  47. Predictors of Outcome • OI at 16 hours was the only significant predictor of mortality in a stepwise logistic regression analysis. • Risk of death increases 2% for every OI increase of 1 at 16 hours • e.g., Patients with OI of 25 have a 55% risk of death, for those with an OI of 15 its only 35% Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  48. MOAT2 Conclusions • Based on a study of only 148 patients, use of HFOV for the treatment of severe ARDS has a 90% predictive value for reducing mortality (p < 0.1) by 29 percent • This reduction trend in mortality is still recognizable (20 percent) at six months in this same population • There may also be benefits related to chronic lung changes as reflected by the small but extended use of respiratory support in the conventional ventilation managed patients Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  49. Clinical Management Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

  50. Managing Large Patients • Special Considerations for Selecting Patients: • Increased Airway Resistance • Increased Physiologic Dead Space • Mean Arterial Pressure < 55 mmhg • Elevated ICP • Passive Pulmonary Blood Flow Dependency Nir Hus MD., PhD., Ryder Trauma Center Jackson Memorial Hospital 2010

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