The management of acute respiratory distress syndrome

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The management of acute respiratory distress syndrome

  1. 1. The Management of Acute Respiratory Distress Syndrome 署立桃園醫院 胸腔內科 林倬睿醫師
  2. 2. Outlines <ul><li>Introduction </li></ul><ul><li>Ventilator strategy </li></ul><ul><li>Adjunctive therapy </li></ul><ul><li>Case demonstration </li></ul>
  3. 3. 定義 Definition <ul><li>急性 Acute onset </li></ul><ul><li>缺氧 PaO2/FiO2 < 200 mmHg </li></ul><ul><li>CXR: bilateral infiltrates 雙側浸潤 </li></ul><ul><li>排除心因性呼吸衰竭 PAWP < 18 mmHg, no clinical evidence of LA HTN </li></ul>
  4. 4. 致病原因 <ul><li>Direct injury </li></ul><ul><ul><li>Pneumonia </li></ul></ul><ul><ul><li>Gastric aspiration </li></ul></ul><ul><ul><li>Drowning </li></ul></ul><ul><ul><li>Fat and amniotic fluid embolism </li></ul></ul><ul><ul><li>Pulmonary contusion </li></ul></ul><ul><ul><li>Alveolar hemorrhage </li></ul></ul><ul><ul><li>Toxic inhalation </li></ul></ul><ul><ul><li>Reperfusion </li></ul></ul><ul><li>Indirect injury </li></ul><ul><ul><li>Severe sepsis </li></ul></ul><ul><ul><li>Transfusions </li></ul></ul><ul><ul><li>Shock </li></ul></ul><ul><ul><li>Salicylate or narcotic overdose </li></ul></ul><ul><ul><li>Pancreatitis </li></ul></ul>
  5. 5. Differential Diagnosis <ul><li>Left ventricular failure </li></ul><ul><li>Intravascular volume overload </li></ul><ul><li>Mitral stenosis </li></ul><ul><li>Veno-occlusive disease </li></ul><ul><li>Lymphangitic carcinoma </li></ul><ul><li>Interstitial and airway diseases </li></ul><ul><ul><li>Hypersensitivity pneumonitis </li></ul></ul><ul><ul><li>Acute eosinophilic pneumonia </li></ul></ul><ul><ul><li>Bronchiolitis obliterans with organising pneumonia </li></ul></ul>Lancet 2007; 369:1553-65
  6. 6. Prognosis & Outcome <ul><li>Predictive of death: advanced age, shock, hepatic failure </li></ul><ul><li>Overall 28-day mortality: 20-40% </li></ul><ul><li>Lung function: returns to normal over 6-12 months </li></ul><ul><li>Common complications: neuropsychiatric problems, neuromuscular weakness </li></ul>Lancet 2007; 369:1553-65
  7. 7. Pathophysiology <ul><li>Exudative phase </li></ul><ul><ul><li>Cytokines  inflammation  surfactant dysfunction  atelectasis </li></ul></ul><ul><ul><li>Elastase  epithelial barrier damage  edema </li></ul></ul><ul><ul><li>Procoagulant tendency  capillary thrombosis </li></ul></ul><ul><li>Fibroproliferative phase </li></ul><ul><ul><li>Chronic inflammation </li></ul></ul><ul><ul><li>Fibrosis </li></ul></ul><ul><ul><li>neovascularisation </li></ul></ul>Lancet 2007; 369:1553-65
  8. 8. NEJM 2000;342:1334-1349
  9. 9. NEJM 2000;342:1334-1349
  10. 10. NEJM 2000;342:1334-1349
  11. 11. Treatment <ul><li>No specific treatment </li></ul><ul><li>Mainstay of treatment: supportive care </li></ul><ul><ul><li>Avoid iatrogenic complications </li></ul></ul><ul><ul><li>Treat the underlying cause </li></ul></ul><ul><ul><li>Maintain adequate oxygenation </li></ul></ul>
  12. 12. Supportive Care <ul><li>Prevention of deep vein thrombosis, gastrointestinal bleeding, and pressure ulcers </li></ul><ul><li>Semi-recumbent position </li></ul><ul><li>Enteral nutrition </li></ul><ul><li>Infection control </li></ul><ul><li>Goal-directed sedation practice </li></ul><ul><li>Glucose control </li></ul>
  13. 13. Ventilator Strategy
  14. 14. Ventilator-induced Lung Injury (VILI) <ul><li>Barotrauma </li></ul><ul><li>Volutrauma </li></ul><ul><li>Atelectrauma </li></ul><ul><li>Biotrauma </li></ul>Over Distension Collapse
  15. 15. Volutrauma <ul><li>Increased alveolar wall stress (stretch) by high tidal volume </li></ul><ul><li>Parenchymal injury </li></ul><ul><ul><li>Gross physical disruption </li></ul></ul><ul><ul><li>Stretch-responsive inflammatory pathways </li></ul></ul>AJRCCM 1998; 157: 294-323
  16. 16. Atelectrauma <ul><li>Cyclic closing and reopening of alveoli </li></ul><ul><li>Alveolar shear stress-related injury </li></ul><ul><li>Heterogeneous nature of lung aeration in ALI/ARDS </li></ul>PEEP PEEP PEEP Lung edema
  17. 17. The PEEP Effect NEJM 2006;354:1839-1841
  18. 18. Ventilator-induced Lung Injury (VILI) Upper Deflection point Lower Inflection point
  19. 19. <ul><li>ARDS Network, 2000: Multicenter, randomized 861 patients </li></ul>Lung-Protective Ventilation NEJM 2000; 342: 1301-1308 39.8% 31.0% Result (p<0.001) 9.1 8.1 Actual PEEP Protocol Protocol PEEP <50 <30 P plateau 12 6 Tidal Volume (ml/kg) Conventional ventilation Lung-protective ventilation 18-24 14-18 14 10-14 10 8-10 5-8 5 PEEP 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 FiO2 Principle for FiO2 and PEEP Adjustment
  20. 20. <ul><li>Result: </li></ul><ul><ul><li>Lower 22% mortality (31% vs 39.8%) </li></ul></ul><ul><ul><li>Increase ventilator-free days </li></ul></ul>Lung-Protective Ventilation NEJM 2000; 342: 1301-1308
  21. 21. Concerns when using lung-protective strategy… <ul><li>Heterogeneous distribution </li></ul><ul><li>Hypercapnia </li></ul><ul><li>Auto-PEEP </li></ul><ul><li>Sedation and paralysis </li></ul><ul><li>Patient-ventilator dyssynchrony </li></ul><ul><li>Increased intrathoracic pressure </li></ul><ul><li>Maintenance of PEEP </li></ul>
  22. 22. Other Ventilator Strategies <ul><li>Lung recruitment maneuvers </li></ul><ul><li>Prone positioning </li></ul><ul><li>High-frequency oscillatory ventilation (HFOV) </li></ul>
  23. 23. Lung Recruitment <ul><li>To open the collapsed alveoli </li></ul><ul><li>A sustained inflation of the lungs to higher airway pressure and volumes </li></ul><ul><ul><li>Ex.: PCV, Pi = 45 cmH2O, PEEP = 5 cmH2O, RR = 10 /min, I : E = 1:1, for 2 minutes </li></ul></ul>NEJM 2007; 354: 1775-1786
  24. 24. Lung Recruitment NEJM 2007; 354: 1775-1786
  25. 25. Lung Recruitment NEJM 2007; 354: 1775-1786
  26. 26. <ul><li>Potentially recruitable (PEEP 5  15 cmH2O) </li></ul><ul><ul><li>Increase in PaO2:FiO2 </li></ul></ul><ul><ul><li>Decrease in PaCO2 </li></ul></ul><ul><ul><li>Increase in compliance </li></ul></ul><ul><li>The effect of PEEP correlates with the percentage of potentially recruitalbe lung </li></ul><ul><li>The percentage of recruitable lung correlates with the overall severity of lung injury </li></ul>Lung Recruitment Sensitivity : 71% Specificity : 59% NEJM 2007; 354: 1775-1786
  27. 27. <ul><li>The percentage of potentially recruitable lung: </li></ul><ul><ul><li>Extremely variable, </li></ul></ul><ul><ul><li>Strongly associated with the response to PEEP </li></ul></ul><ul><li>Not routinely recommended </li></ul>Lung Recruitment
  28. 28. Prone Position
  29. 29. Prone Position <ul><li>Mechanisms to improve oxygenation: </li></ul><ul><ul><li>Increase in end-expiratory lung volume </li></ul></ul><ul><ul><li>Better ventilation-perfusion matching </li></ul></ul><ul><ul><li>More efficient drainage of secretions </li></ul></ul>
  30. 30. Prone Position NEJM 2001;345:568-573
  31. 31. Prone Position NEJM 2001;345:568-573
  32. 32. <ul><li>Improve oxygenation in about 2/3 of all treated patients </li></ul><ul><li>No improvement on survival, time on ventilation, or time in ICU </li></ul><ul><li>Might be useful to treat refractory hypoxemia </li></ul><ul><li>Optimum timing or duration ? </li></ul><ul><li>Routine use is not recommended </li></ul>Prone Position
  33. 33. High-Frequency Oscillatory Ventilation (HFOV)
  34. 34. HFOV Frequency: 180-600 breaths/min (3-10Hz)
  35. 35. Effect of HFOV on gas exchange in ARDS patients AJRCCM 2002; 166:801-8
  36. 36. Survival difference of ARDS patients treated with HFOV or CMV 30-day: P=0.057 90-day: P=0.078 AJRCCM 2002; 166:801-8
  37. 37. HFOV <ul><li>Complications: </li></ul><ul><ul><li>Recognition of a pneumothorax </li></ul></ul><ul><ul><li>Desiccation of secretions </li></ul></ul><ul><ul><li>Sedation and paralysis </li></ul></ul><ul><ul><li>Lack of expiratory filter </li></ul></ul><ul><li>Failed to show a mortality benefit </li></ul><ul><li>Combination with other interventions ? </li></ul>Chest 2007; 131:1907-1916
  38. 38. Adjunctive Therapy <ul><li>Steroid treatment </li></ul><ul><li>Fluid management </li></ul><ul><li>Extracorporeal membrane oxygenation (ECMO) </li></ul><ul><li>Nitric oxide </li></ul><ul><li>Others </li></ul>
  39. 39. Steroid therapy NEJM 2006;354:1671-1684
  40. 40. <ul><li>Increase the number of ventilator-free and shock-free days during the first 28 day </li></ul><ul><li>Improve oxygenation, compliance and blood pressure </li></ul><ul><li>No increase in the rate of infectious complications </li></ul><ul><li>Higher rate of neuromuscular weakness </li></ul><ul><li>Routine use of steroid is not supported </li></ul><ul><li>Starting steroid more than 14 days after the onset of ARDS may increase mortality </li></ul>Steroid therapy NEJM 2006;354:1671-1684
  41. 41. Fluid Management NEJM 2006;354:2564-2575
  42. 42. Fluid Management NEJM 2006;354:2564-2575
  43. 43. Fluid Management NEJM 2006;354:2213-24
  44. 44. <ul><li>Conservative strategy improves lung function and shortens the duration of ventilator use and ICU stay </li></ul><ul><li>No significant mortality benefit </li></ul><ul><li>The use of pulmonary artery catheter not routinely suggested </li></ul>Fluid Management
  45. 45. Extracorporeal Membrane Oxygenation (ECMO) <ul><li>No improvement on survival or time on ventilation </li></ul><ul><li>Substantial risk of infection and bleeding </li></ul><ul><li>Not routinely recommended </li></ul>
  46. 46. Nitric Oxide <ul><li>Vasodilator </li></ul><ul><li>Improve oxygenation and pulmonary vascular resistance </li></ul><ul><li>No improvement on survival </li></ul><ul><li>Routine use is not recommended </li></ul>
  47. 47. Unproven Treatments <ul><li>Ketoconazole </li></ul><ul><li>Pentoxyfilline and lisofylline </li></ul><ul><li>Nutritional modification </li></ul><ul><li>Antioxidants </li></ul><ul><li>Neutrophil elastase inhibition </li></ul><ul><li>Surfactant </li></ul><ul><li>Liquid ventilation </li></ul>Lancet 2007; 369:1553-65
  48. 48. Conclusions <ul><li>The only treatment that shows mortality benefit: </li></ul><ul><ul><li>lung-protective ventilation strategy </li></ul></ul><ul><ul><li>Low tidal volume (6ml/Kg), high PEEP, adequate Pplat (<30 cmH2O) </li></ul></ul><ul><li>Modalities to improve oxygenation: </li></ul><ul><ul><li>Prone position, steroid, fluid treatment, steroid, HFOV, NO </li></ul></ul><ul><li>Combining other treatments: </li></ul><ul><ul><li>Activated protein C, antibiotics, EGDT…etc </li></ul></ul>

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