- Chest radiography is useful for assessing pulmonary edema, infiltrates, effusions, pneumothorax, and positioning of lines and tubes in intensive care patients. Common findings include air bronchograms, hilar enlargement, Kerley lines, and increased vascular pedicle width. - Pneumomediastinum is suggested by findings like the continuous diaphragm sign, Naclerio's V sign, and double bronchial wall sign. A pneumothorax may be occult or demonstrated by a pleural line with absent lung markings. - Proper positioning of central lines is important but can be challenging due to anatomical variability. The tip should lie in the SVC above the pericardial

1. Chest Radiology in Intensive Care Medicine Dr. Andrew Ferguson MEd FRCA DIBICM FCCP Assistant Professor, Medicine (Critical Care) & Anesthesia Dalhousie University

2. Overview Air bronchograms & silhouette sign Hilar enlargement Alveolar & interstitial infiltrates Effusions Pulmonary oedema Assessment of volume status using CXR Lobar anatomy & collapse Abnormal air collections Lines, tubes and drains

3. Radiographic anatomy Or LA NOTE In spite of what you May have heard… The right heart border Is formed by left atrium in up to 38% of patients AV TV MV

4. Air bronchograms Bronchi normally invisible as they are thin-walled, filled with air , and surrounded by air Except when alveoli fill with substance with the density of fluid e.g. Pulmonary oedema Blood Gastric aspirate Inflammatory exudate Bronchi visible when surrounded by diseased lung = air bronchogram

5. Silhouette Sign When an object is in contact with another of different density the adjoining edge is visible e.g. heart border against aerated lung When objects of the same density are in contact the adjoining edge is invisible e.g. heart border against consolidated lung

6. Silhouette Sign Lobe Silhouetted structure Right middle lobe Right heart border Left lingula Left heart border Right lower lobe Right hemidiaphragm Left lower lobe Left hemidiaphragm Post apical segment left upper lobe Aortic knob Ant segment right upper lobe Ascending aorta

7. Hilar enlargement Unilateral hilar adenopathy Neoplasm Primary Tuberculosis Sarcoidosis (3-8%) Primary pulmonary fungal infection Bilateral hilar adenopathy Sarcoidosis may also see right paratracheal nodes Lymphoma False positive Expiration film Pulmonary Hypertension

8. Alveolar infiltrates Air bronchograms “ Fluffy” / indistinct appearance Segmental or lobar distribution Homogeneous & confluent What can fill alveoli? Water: pulmonary oedema Protein: ARDS, alveolar proteinosis Fibrous tissue: BOOP, radiation Cells: Neutrophils : pneumonia; pneumonitis Eosinophils : eosinophilic pneumonia RBCs : DAH, contusion, infarction, vasculitis Neoplastic : carcinoma, lymphoma, Lymphocytes : pneumonitis, sarcoidosis

9. Rapid Clearance of Alveolar Infiltrate Pulmonary oedema Pulmonary haemorrhage Aspiration Pneumococcal pneumonia (possibly)

10. Interstitial Infiltrates Inhomogeneous Discrete No bronchograms Reticular (lines) and/or Nodular (circles) Fibrosis Connective tissue disease Sarcoidosis Radiation fibrosis Asbestosis Lymphangitis carcinomatosis Silicosis TB

11. Pleural effusions

12. Pleural Effusion Appearances Subpulmonic effusion Blunting of Costophrenic angle Meniscus sign Layering Loculated Laminar effusion Subpleural between lung & pleura Opacified hemithorax Air-fluid levels

13. Subpulmonic Effusion Tented diaphragmatic dome or apex more lateral than expected Costophrenic angle more shallow than expected Elevated diaphragm appears thicker and more separated from gastric bubble Usually < 350 ml volume

14. Blunting of Costo-phrenic Angle 200-300 ml effusion required (AP film) 100-150 ml blunts posterior angle on lateral CXR

15. Pulmonary Oedema

16. Pulmonary Oedema ? Upper lobe diversion (“cephalization”) Infiltrates Batswing Diffuse Pleural effusions Septal lines e.g. Kerley B Basal, 1-2 cm long, straight, 90 o to pleura Thickening of fissures Peribronchial cuffing Interstitial Oedema

17. Left atrial pressure & CXR signs

18. < 10% of cases of pulmonary oedema, usually in rapid onset oedema e.g. acute MR

19. Kerley B lines

20. Peribronchial Cuffing May be normal finding if right at hilum

21. Asymmetric pulmonary oedema Chronic lung disease altering vascular flow Acute MR - jet to right pulm vein often RUL Patient position (gravitational) Re-expansion

22. Vascular Pedicle Width in Pulmonary Oedema

23. Martin, G. S. et al. Chest 2002;122:2087-2095 Landmarks for measurement of VPW and CTR on a routine CXR

24. Vascular pedicle width and fluid status in pulmonary oedema

25. Using Vascular Pedicle Width

26. VPW/CTR as predictor of PCWP > 18 Criteria Sensitivity Specificity PPV NPV Odds ratio VPW > 70 & CTR > 0.55 54% 83% 76% 65% 3.2 VPW > 70 69% 72% 70% 72% 2.5 CTR > 0.55 63% 50% 56% 57% 1.3

27. Lobar anatomy and collapse

28. Lobar anatomy & collapse

29. RUL collapse

30. RML collapse Indistinct right heart border

31. RLL collapse Fissure may be visible Sail-like line behind right heart plus indistinct diaphragm

32. LUL Collapse Lufsichel sign = Aerated superior segment of left lower lobe interposes between collapsed upper lobe and mediastinum producing lucency around aorta

33. LLL collapse Sail-like line behind heart – occasionally seen as extremely straight heart border

34. Total collapse

35. Abnormal Air Collections Subcutaneous emphysema Pneumomediastinum Pneumothorax Pulmonary interstitial emphysema

36. Pulmonary Interstitial Emphysema Much more common in neonates, rare in adults Alveolar rupture: air dissects into pulmonary interstitium Factors associated: Anything increasing intrapulmonary pressure Ventilation with peak airway pressures > 30 cm H 2 0 RDS or ARDS severity Associated pulmonary abnormalities CXR features : subtle & often hidden by other pathology Multiple small and large parenchymal cysts Small, mottled or streaky lucencies extending from hilum Perivascular halos from air collections Intra-septal air Subpleural cysts

37. Pulmonary Interstitial Emphysema

38. Pneumomediastinum Sources of air Intrathoracic Trachea and major bronchi Esophagus Lung Pleural space Extrathoracic Head and neck Intraperitoneum and retroperitoneum

39. CXR Signs of Pneumomediastinum Thymic sail sign (infants/young children) Tubular artery sign (AP film) “ Ring around the artery” sign (lateral film) Double bronchial wall sign Continuous diaphragm sign Extrapleural air Naclerio ’s V sign Linear density parallel to heart border Dissection of air into neck Dissection of air into chest wall

40. Continuous diaphragm sign

41. Naclerio’s V sign Lucent band of gas extending along descending aorta and intersecting band of gas that extends along medial left hemi- diaphragm, together forming “V’

42. Double bronchial wall sign Air on both sides of bronchial wall makes full wall visible

43. “ Ring around the artery” sign Air around pulmonary artery

44. Tubular artery sign Air outlining left subclavian & left carotid

45. Thymic sail sign Thymus outlined by air Also air tracking up into neck

46. Extrapleural air e.g. pleura peeled off diaphragm

47. Mediastinal air

48. Mediastinal air running parallel to descending aorta

49. Pneumomediastinum vs pneumothorax

50. Pneumomediastinum vs pneumocardium

51. Pneumopericardium

52. Pitfalls – Mach band effect “ The Mach band effect is associated with convex surfaces, appearing as a region of lucency adjacent to structures with convex borders. The absence of an (associated) opaque line, which is typically seen in pneumomediastinum, can aid in differentiation ” Zylak C. Pneumomediastinum Revisited. Radiographics 2000; 20: 1043-1057.

53. Pneumothorax Apicolateral visceral pleural line Generally requires erect/semi-erect film Skin fold may be mistaken for pleural line Lack of lung markings outside line Caution in COPD/bullous disease Bullae generally convex ICU CXR often supine/semi-erect Different criteria for diagnosis Often subtle WATCH OUT!

54. “ Occult” pneumothorax Crisp cardiac silhouette with increased lucency

55. Occult pneumothorax II Cardiophrenic sulcus highly visible Crisp heart border

56. Potential signs of pneumothorax Pleural line with absent markings Double diaphragm sign Visible anterior costophrenic recess interface Sharpened cardiac silhouette & apex Hyperlucent hemithorax Inferior edge of collapsed lung Deep sulcus sign Depressed diaphragm Apical pericardial fat Discrete lobulated densities (1-1 .5cm) adjacent to cardiac apex

57. Tension pneumothorax Flattening of heart border Flattening of adjacent vascular structures e.g. SVC Mediastinal shift - AWAY Diaphragmatic inversion

58. Double diaphragm sign

59. Pneumothorax in Supine Patients Anteromedial - unusually sharp outline of: Mediastinal vascular structures Heart border Cardiophrenic sulcus Posteromedial Lucent band outlining mediastinal surface of a collapsed lower lobe Increased visibility of paraspinous line & descending aorta Increased visibility of posterior costophrenic sulcus Subpulmonic Hyperlucent upper abdominal quadrant Deep costophrenic sulcus (“deep sulcus” sign) Sharp hemidiaphragm despite opacification in lower lobe of lung (if consolidated) Visualisation of inferior surface of consolidated lung

60. Posteromedial Pneumothorax

61. Subpulmonic pneumothorax Deep sulcus, lucent RUQ Rankine, J. J et al. Postgrad Med J 2000;76:399-404

62. Anteromedial pneumothorax Sharp outline of mediastinum and right heart border. Right hemithorax has concurrent consolidation and effusion Rankine, J. J et al. Postgrad Med J 2000;76:399-404

63. Mimics - Skin fold

64. Subcutaneous emphysema

65. Lines, tubes and drains

66. Central line positioning - issues Right upper heart border is left atrium, not the right , in 38% of patients Radiographic SVC/RA junction: hard to see in 10% inaccurate: can be up to 2.8 cm higher than echocardiographic junction not all lines within heart shadow on xray are in the RA CVC tip should lie in SVC above pericardial reflection (but no radiographic marker of this structure) BUT is acceptable for dialysis line tip to lie at SVC/RA junction or in RA Line should lie parallel to vessel wall Line tip < 2.9 cm beyond take-off of right main bronchus is always in SVC Right tracheobronchial angle is always below junction of brachiocephalic veins Carina is mean of 1.3 cm below mid-point of the SVC and up to 0.7 cm below pericardial reflection – is suitable location for line tip

67. British Journal of Anaesthesia 2006 96(3):335-340

68. Catheter tips abutting SVC wall – risk of perforation

70. Malposition – subclavian line into jugular vein

71. Images to review

72. Asthma + diversion + peribronchial cuffing

73. Right Haemothorax with bullet

74. LUL collapse + LLL collapse

75. Linear (plate) atelectasis + small bowel obstruction

76. Bilateral hilar enlargement - lymphoma

77. Bilateral cavitating lesions with fluid levels - Staph abcess

78. Chilaiditi's syndrome – colon interspersed between liver/spleen and diaphragm

79. Deep sulcus sign – left pneumothorax

81. Diffuse alveolar haemorrhage

82. Node in aortopulmonary window

83. Fluid level behind heart – hiatus hernia

84. Silicone breast implants

85. Pneumothorax - blocked chest drain

86. Subcutaneous emphysema, LIJ CVC tip position poor

87. Residual haemothorax on left with chest tube and LLL collapse/consolidation + air bronchogram: haemothorax on right. Oesophagus displaced to left