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Pediatric ards fortenberry


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Pediatric ards fortenberry

  1. 1. Pediatric ARDS: Understanding It and Managing It James D. Fortenberry, MD Medical Director, Pediatric and Adult ECMO Medical Director, Critical Care Medicine Children’s Healthcare of Atlanta at Egleston
  2. 2. New and Improved Adult Respiratory Distress Syndrome Acute Respiratory Distress Syndrome
  3. 3. ARDS: New Definition <ul><li>Criteria </li></ul><ul><ul><li>Acute onset </li></ul></ul><ul><ul><li>Bilateral CXR infiltrates </li></ul></ul><ul><ul><li>PA pressure < 18 mm Hg </li></ul></ul><ul><ul><li>Classification </li></ul></ul><ul><ul><ul><li>Acute lung injury - P a O 2 : F 1 O 2 < 300 </li></ul></ul></ul><ul><ul><ul><li>Acute respiratory distress syndrome - P a O 2 : F 1 O 2 < 200 </li></ul></ul></ul>- 1994 American - European Consensus Conference
  4. 4. Clinical Disorders Associated with ARDS
  5. 5. The Problem: Lung Injury Other 4% Hemorrhage 5% Trauma 5% Noninfectious Pneumonia 14% Cardiac Arrest 12% Septic Syndrome 32% Infectious Pneumonia 28% Davis et al., J Peds 1993;123:35
  6. 6. ARDS - Pathogenesis <ul><li>Instigation </li></ul><ul><li>Endothelial injury: increased permeability of alveolar - capillary barrier </li></ul><ul><li>Epithelial injury : alveolar flood, loss of surfactant, barrier vs. infection </li></ul><ul><li>Proinflammatory mechanisms </li></ul>
  7. 7. ARDS Pathogenesis <ul><li>Resolution </li></ul><ul><li>Equally important </li></ul><ul><li>Alveolar edema - resolved by active sodium transport </li></ul><ul><li>Alveolar type II cells - re-epithelialize </li></ul><ul><li>Neutrophil clearance needed </li></ul>
  8. 9. ARDS - Pathophysiology <ul><li>Decreased compliance </li></ul><ul><li>Alveolar edema </li></ul><ul><li>Heterogenous </li></ul><ul><li>“ Baby Lungs” </li></ul>
  9. 10. ARDS:CT Scan View
  10. 11. Phases of ARDS <ul><li>Acute - exudative, inflammatory </li></ul><ul><ul><li>(0 - 3 days) </li></ul></ul><ul><li>Subacute - proliferative </li></ul><ul><ul><li>(4 - 10 days) </li></ul></ul><ul><li>Chronic - fibrosing alveolitis </li></ul><ul><ul><li>( > 10 days) </li></ul></ul>
  11. 13. ARDS - Outcomes <ul><li>Most studies - mortality 40% to 60%; similar for children/adults </li></ul><ul><li>Death is usually due to sepsis/MODS rather than primary respiratory </li></ul><ul><li>Mortality may be decreasing </li></ul><ul><ul><li>53/68 % 39/36 % </li></ul></ul>
  12. 14. ARDS - Principles of Therapy <ul><li>Provide adequate gas exchange </li></ul><ul><li>Avoid secondary injury </li></ul>
  13. 15. Therapies for ARDS Innovations: NO PLV Proning Surfactant Anti-Inflammatory Mechanical Ventilation Gentle ventilation: Permissive hypercapnia Low tidal volume Open-lung HFOV ECMO IVOX IV gas exchange AVCO 2 R Total Implantable Artificial Lung ARDS Extrapulmonary Gas Exchange
  14. 16. The Dangers of Overdistention <ul><li>Repetitive shear stress </li></ul><ul><li>Injury to normal alveoli </li></ul><ul><li>inflammatory response </li></ul><ul><li>air trapping </li></ul><ul><li>Phasic volume swings: volutrauma </li></ul>
  15. 17. <ul><li> compliance </li></ul><ul><li> intrapulmonary shunt </li></ul><ul><li> FiO 2 </li></ul><ul><li>WOB </li></ul><ul><li>inflammatory response </li></ul>The Dangers of Atelectasis
  16. 18. Lung Injury Zones Atelectasis “ Sweet Spot” Overdistention
  17. 19. ARDS: George Bush Therapy <ul><li>“ Kinder, gentler” forms of ventilation: </li></ul><ul><li>Low tidal volumes (6-8 vs.10-15 cc/kg) </li></ul><ul><li>“ Open lung”: Higher PEEP, lower PIP </li></ul><ul><li>Permissive hypercapnia: tolerate higher pCO 2 </li></ul>
  18. 20. Lower Tidal Volumes for ARDS * * * p < .001 ARDS Network, NEJM, 342: 2000 22% decrease
  19. 21. Is turning the ARDS patient “prone” to be helpful?
  20. 22. Prone Positioning in ARDS <ul><li>Theory: let gravity improve matching perfusion to better ventilated areas </li></ul><ul><li>Improvement immediate </li></ul><ul><li>Uncertain effect on outcome </li></ul>
  21. 24. Prone Positioning in Pediatric ARDS: Longer May Be Better <ul><li>Compared 6-10 hrs PP vs. 18-24 hrs PP </li></ul><ul><li>Overall ARDS survival 79% in 40 pts. </li></ul><ul><ul><ul><li>Relvas et al., Chest 2003 </li></ul></ul></ul>
  22. 25. Brief vs. Prolonged Prone Positioning in Children Oxygenation Index (OI) - Relvas et al., Chest 2003 * * **
  23. 26. High Frequency Oscillation: A Whole Lotta Shakin’ Goin’ On
  24. 27. It’s not absolute pressure, but volume or pressure swings that promote lung injury or atelectasis. - Reese Clark
  25. 28. <ul><li>Rapid rate </li></ul><ul><li>Low tidal volume </li></ul><ul><li>Maintain open lung </li></ul><ul><li>Minimal volume swings </li></ul>High Frequency Ventilation
  26. 29. High Frequency Oscillatory Ventilation
  27. 31. HFOV is the easiest way to find the ventilation “ sweet spot”
  28. 32. HFOV: Benefits Vs. Conventional Ventilation
  29. 33. HFOV vs. CMV in Pediatric Respiratory Failure - Arnold et al, CCM , 1994 *
  30. 34. Surfactant in ARDS <ul><li>ARDS: </li></ul><ul><ul><li>surfactant deficiency </li></ul></ul><ul><ul><li>surfactant present is dysfunctional </li></ul></ul><ul><li>Surfactant replacement improves physiologic function </li></ul>
  31. 35. Surfactant in Pediatric ARDS <ul><li>Current randomized multi-center trial </li></ul><ul><li>Placebo vs calf lung surfactant (Infasurf) </li></ul><ul><li>Children’s at Egleston is a participating center-study closed, await results </li></ul>
  32. 36. Steroids in Unresolving ARDS <ul><li>Randomized, double-blind, placebo-controlled trial </li></ul><ul><li>Adult ARDS ventilated for > 7 days without improvement </li></ul><ul><li>Randomized: </li></ul><ul><ul><li>Placebo </li></ul></ul><ul><ul><li>Methylprednisolone 2 mg/kg/day x 4 days, tapered over 1 month </li></ul></ul>Meduri et al, JAMA 280:159, 1998
  33. 37. Steroids in Unresolving ARDS * * p<.01 * - Meduri et al., JAMA, 1998
  34. 38. Steroids in Unresolving ARDS <ul><li>Randomized, double-blind, placebo-controlled trial </li></ul><ul><li>ARDSNetwork-180 adults </li></ul><ul><li>Randomized: </li></ul><ul><ul><li>Placebo </li></ul></ul><ul><ul><li>Methylprednisolone </li></ul></ul><ul><ul><li>No mortality difference </li></ul></ul><ul><ul><li>Decreased ventilator-free days but only if started 7-14 days </li></ul></ul>Steinberg, NEJM, 354:1671,2006
  35. 39. Inhaled Nitric Oxide in Respiratory Failure <ul><li>Neonates </li></ul><ul><ul><li>Beneficial in term neonates with PPHN </li></ul></ul><ul><ul><li>Decreased need for ECMO </li></ul></ul><ul><li>Adults/Pediatrics </li></ul><ul><ul><li>Benefits - lowers PA pressures, improves gas exchange </li></ul></ul><ul><ul><li>Randomized trials: No difference in mortality or days of ventilation </li></ul></ul>
  36. 41. Inhaled NO and HFOV In Pediatric ARDS Dobyns et al., J Peds , 2000 *
  37. 42. Partial Liquid Ventilation
  38. 43. Partial Liquid Ventilation <ul><li>Mechanisms of action </li></ul><ul><ul><li>oxygen reservoir </li></ul></ul><ul><ul><li>recruitment of lung volume </li></ul></ul><ul><ul><li>alveolar lavage </li></ul></ul><ul><ul><li>redistribution of blood flow </li></ul></ul><ul><ul><li>anti-inflammatory </li></ul></ul>
  39. 44. Liquid Ventilation <ul><li>Pediatric trials started in 1996 </li></ul><ul><ul><li>Partial: FRC (15 - 20 cc/kg) </li></ul></ul><ul><ul><li>Study halted 1999 due to lack of benefit </li></ul></ul><ul><ul><li>Adult study (2001): no effect on outcome </li></ul></ul>
  40. 45. ARDS- “Mechanical” Therapies Prone positioning - Unproven outcome benefit Low tidal volumes - Outcome benefit in large study Open-lung strategy - Outcome benefit in small study HFOV -Outcome benefit in small study ECMO - Proven in neonates unproven in children
  41. 46. Pharmacologic Approaches to ARDS: Randomized Trials Glucocorticoids Fibrosing alveolitis - lowered mortality, small study Surfactant - possible benefit in children Inhaled NO - no benefit Partial liquid ventilation - no benefit
  42. 47. “…We must discard the old approach and continue to search for ways to improve mechanical ventilation. In the meantime, there is no substitute for the clinician standing by the ventilator…” - Martin J. Tobin, MD