Imaging of Lung Edema

Transcript

1. Radiography of lung edema Howard Mann, M.D. Department of Radiology and Imaging Sciences
2. Definition: An increase in lung water Mechanisms: 1. Increased fluid filtration from the pulmonary capillary 2. Impaired clearance of lung water normally passing into the pulmonary interstitium
3. Mechanisms of fluid filtration from a capillary - the Starling equation is the reflection coefficient for movement of proteins across the capillary wall (from 0 if completely permeable to 1 if impermeable)
4. Clearance and accumulation of filtered fluid In the lung a small amount of fluid normally moves from the capillary to the interstitium
5. Lung edema forms when factors involved in the Starling Equation promote edema formation 1. Hydrostatic lung edema 2. Acute lung injury edema [increased-permeability] Synonyms for 2.: - non-hydrostatic edema - increased-permeability lung edema - non-cardiogenic edema Left atrial hypertension from cardiac disease Left atrial hypertension from an expanded blood volume
6. Acute lung injury The pathologic substrate (Diffuse Alveolar Damage) of the Acute Respiratory Distress Syndrome Alveolar-capillary barrier Berlin definition
7. Hydrostatic lung edema Sequence of events 1. Left atrial hypertension 2. Pulmonary venous and capillary hypertension Radiography: Pulmonary vascular distention 3. Increased transcapillary fluid filtration 4. Accumulation and clearance of filtered fluid Radiography: Interstitial and alveolar edema Pleural fluid accumulation
8. Findings in cardiogenic edema redistribution
9. Findings in overhydration lung edema
10. Findings in acute lung injury edema
11. Howard Mann, M.D. University o Utah
12. Key Points:
13. Distribution of pulmonary blood flow Normal Balanced • Increased pulmonary blood volume as a manifestation of an expanded circulating blood volume - “intravascular volume overload” • Increased pulmonary blood flow as a manifestation of a left-to-right shunt Inversion
14. Distribution of pulmonary blood flow. Radiography with the patient erect SPV SPV Normal Balanced Inversion
15. vs Balanced Inversion
16. Discerning pulmonary venous hypertension in hydrostatic lung edema Vascular distention and blood flow distribution Key Points: • Inversion of pulmonary blood flow is a sequel of chronic pulmonary venous hypertension: chronic and irreversible structural changes in lower lung zone vessels >> increased regional resistance to blood flow. • Inversion of blood flow is not a feature of acute pulmonary venous hypertension
17. Pulmonary venous pressure and lung edema in chronic pulmonary venous hypertension Increased liquid clearance capacity via lymphatic expansion
18. The vascular pedicle, elevated CVP and an expanded blood volume
19. Howard Mann, M.D. University o Utah Normal Expanded blood volume Clinical example * * * * svc svc Elevated CVP azygous v.
20. Clearance of lung edema fluid 1. Pulmonary lymphatics 2. Hydrostatic pressure gradients and water flow in the pulmonary interstitium... 3. Clearance of interstitial water into the mediastinum and pleural space
22. Pathways for the clearance of interstitial water • along bronchovascular sheaths to the mediastinum • along a hydrostatic pressure gradient to the subpleural interstitial compartment... • into the pleural space Key Point: the radiographic signs of interstitial edema depict these pathways
24. The three “classic” signs of interstitial edema: • peri-bronchial fluid cuffs • septal lines • sub[visceral] pleural edema (interlobar fissures)
25. Peri-bronchial fluid cuffs Bronchoarterial bundle
26. Peri-bronchial fluid cuffs on radiography
27. Normal Fluid cuff around bronchus intermedius
28. Septal (Kerley) lines
29. Subpleural interstitial edema
30. subpleural interstitium interlobular septum
31. From the subpleural interstitium to the pleural space
32. Passage of peribronchovascular sheath water into mediastinum
34. Current Prior Mediastinal fat edema
35. Prior for comparison
36. Mediastinal fat (**) and nodal (*) edema * **
37. Clinical cases Radiographic-CT correlation
38. Hydrostatic lung edema in chronic heart disease
40. Previous day
41. septal lines subpleural edema
42. peri-bronchial fluid cuff
44. subpleural edema
45. Hydrostatic lung edema as a consequence of intravascular fluid overload
47. Recent comparison
48. A patient being treated for pro-myelocytic leukemia Acute lung injury edema
49. Acute lung injury edema
50. Acute CR arrest in a patient with a history of mitral valve replacement Clinical case 1 For each of the three following cases, try decide if the mechanism is: hydrostatic or acute lung injury edema
52. Clinical case 2: A ski tourist in Utah — acute respiratory distress
53. Clinical case 3. A patient in the Neurointensive Care Unit
57. Impaired clearance of lung water Obstruction of lymphatics • Obstruction of lymphatics in the lung • Obstruction of lymphatic flow in afferent and efferent lymphatic channels in intrapulmonary hilar lymph nodes • Loss of lymphatic connections — lung transplantation
58. Dyspnea in a previously health female
61. Open-lung biopsy
62. History of cervical cancer
63. Interstitial edema from tumor-obstruction of lymphatics (Also: parenchymal and intra-vascular metastases) Lymphangitic tumor spread
65. Final clinical case (very uncommon entity)
66. Note: Mild interstitial edema
67. Dx: Pulmonary veno-occlusive disease Pulmonary artery occlusion pressure: normal Key points: i. Thrombosis involves small pulmonary veins and venules, and is heterogeneous in distribution ii. A “wedged” PA catheter sees a static column of blood between the tip and left atrium