EMERGENCIES IN THE CHEST. Michal Kozub

Transcription

1 EMERGENCIES IN THE CHEST Michal Kozub

2 CHEST IMAGING

3 CHEST IMAGING

4 1.Consolidation - any pathologic process that fills the alveoli with fluid, pus, blood, cells (including tumor cells) or other substances resulting in lobar, diffuse or multifocal ill-defined opacities. 2.Interstitial - involvement of the supporting tissue of the lung parenchyma resulting in fine or coarse reticular opacities or small nodules. 3.Nodule or mass - any space occupying lesion either solitary or multiple. 4.Atelectasis - collapse of a part of the lung due to a decrease in the amount of air in the alveoli resulting in volume loss and increased density.

5 CHEST RADIOGRAPH Portable chest radiography is the initial imaging method used at the emergency workup of the polytrauma patient and it is useful for detecting serious life-threatening conditions, such as a tension pneumothorax or haemothorax, mediastinal haematoma, flail chest or malpositioned tubes. Usually AP Often supine Frequently in poor inspiration 405/

6 CT The superiority of CT over chest radiography has been documented in the literature. CT detects significant disease in patients with normal initial radiographs and in 20% will reveal more extensive injuries compared with the abnormal initial radiographs, necessitating a change of management. Reformats without additional scanning. Usually on spontaneous breath Motion artifact Metal artifact/high-density foreign material artifact

7 MRI MRI allows the radiologist to directly evaluate the soft tissues of the spine and is, therefore, crucial in the evaluation of the patient with ligamentous injury and instability. a prolonged acquisition time unavailability at many institutions contraindications, including patients with pacemakers, ferromagnetic aneurysm clips, metallic fragments in the spinal cord, and claustrophobia. MRI in acute spinal trauma By Michael C. Hollingshead, MD, and Mauricio Castillo, MD, FACR

8 When computed tomographic angiography (CTA) is contraindicated, MRI and MRA are important alternative imaging modalities for diagnosis and management of patients with acute PE, AD and MI. MRI Hochhegger B, Ley-Zaporozhan J, Marchiori E, et al. Magnetic resonance imaging findings in acute pulmonary embolism. The British Journal of Radiology. 2011;84(999): doi: /bjr/

9 ULTRASOUND???? Focused Assessment Sonography for Trauma (FAST) Since CT has better accuracy for diagnosing torso injuries, the FAST exam is most useful in situations where CT is not practical due to time constraints or when CT scan can be reasonably avoided.

10 CLINICAL SCENARIOS WHERE FAST IS MOST USEFUL: Hemodynamically unstable patients, when the cause of hypotension is unclear. Patients who need an emergent bedside procedure. Patients at a community hospital who require transfer to a trauma center. Consider pericardiocentesis if a pericardial effusion is found, consider early blood transfusion for significant hemoperitoneum, and consider a chest tube if a hemothorax or pneumothorax is discovered, especially if aeromedical transport is planned. Intoxicated patients who can be observed and reexamined. Patients with penetrating trauma with multiple wounds or unclear trajectory, especially with wounds in upper abdomen or lower chest. Patients with a concerning mechanism of injury but no indication for CT. Consider a period of observation and serial FAST exams.

11 CHEST EMERGENCIES Trauma Non traumatic emergencies

12 TRAUMA Lung trauma Pulmonary contusions Pulmonary lacerations Traumatic lung herniation Torsion of the lung Pneumothorax Haemothorax Haemopneumothorax Tracheobronchial injuries Mediastinal Pneumomediastinum Mediastinal haematoma Aortic injury Oesophageal injuries Thoracic duct trauma Cardiac trauma

13 TRAUMA Skeletal trauma Rib fractures Flail chest Sternal fractures Scapula fractures Thoracic spine fractures Diaphragmatic trauma Diaphragmatic injuries Oikonomou A, Prassopoulos P. CT imaging of blunt chest trauma. Insights into Imaging. 2011;2(3): doi: /s

14 NON TRAUMA Pulmonary embolism Pneumothorax ( tension pneumothorax ) Airway foreign bodies Pneumoperitoneum Pericardial effusions Acute respiratory distress syndrome Thoracic aortic aneurysms Diaphragmatic hernias Congestive heart failure Aspiration pneumonia Hydropneumothorax

15 ATELECTASIS Atelectasis, (also called collapse), a loss of volume of lung parenchyma caused by a reduced inflation. Some mechanisms may be responsible for atelectasis: bronchial obstruction extrinsic compression such as pleural fluid or air, or the presence of any space-occupying intrathoracic lesion resulting in extrinsic compression of adjacent parenchyma; cicatrization atelectasis resulting from lung parenchymal fibrosis; adhesive atelectasis resulting from loss of surfactant.

16 ATELECTASIS The most frequent cause of atelactasis is bronchial obstruction. The major radiological signs of atelectasis are opacity of the lobe/lung and evidence of loss of volume. Opacity results from the presence of intra-alveolar fluid in the case of obstructive atelectasis or passive atelectasis or from scarring or lung fibrosis in the case of cicatrization atelectasis.

17 ATELECTASIS The signs of loss of volume include: displacement of fissures, pulmonary blood vessels and major bronchi, Shift of other structures to compensate for the loss of volume. In the case of obstructive atelectasis, the presence of a large tumour mass located in a parahilar situation may produce a bulge in the contour of the collapsed lobe (golden S sign)

18 ATELECTASIS OF RIGHT UPPER LOBE The right hilum becomes elevated; The major and minor fissures are displaced upwards and rotated towards the mediastinum. As a result, the collapsed lobe packs against the mediastinum and lung apex.

19 ATELECTASIS OF LEFT UPPER LOBE The hilum is displaced upwards and the major fissure forwards (next slice). The lobe retains much of its original contact with the anterior chest wall. Displacement of the anterior mediastinum fat and displacement of the trachea towards the left are commonly present. The left hemidiaphragm is moderately elevated

20 ATELECTASIS OF MIDDLE LOBE The collapsed right middle lobe is easily recognized on the lateral chest radiograph. The major and minor fissures move towards one another and the collapsed lobe resembles a curved, elongated wedge. The right hilum is not displaced. The right hemidiaphragm and mediastinum are in a normal position.

21 ATELECTASIS OF LOWER LOBE The lower lobe collapse is seen with obstruction to lower lobe s bronchus. The major fissure is displaced downward and backward creating an opacity that obliterates the dome of the hemidiaphragm. Ipsilateral hilum, mainstem bronchus and upper lobar bronchus are displaced downward.

22 AIRWAY FOREIGN BODIES Airway foreign bodies are most often found in pediatric patients. The most common site of foreign bodies is the right mainstem bronchus due to its posterior location, shallow angle to the trachea and wide diameter. The density of the ingested item will determine whether it can be directly identified on radiographs.

23 Indirect signs of ingestion include: focal overinflation (if there is partial obstruction), atelectasis (if there is more complete obstruction). AIRWAY FOREIGN BODIES

24 PERICARDIAL EFFUSIONS Pericardial effusions result from the accumulation of fluid within the pericardial space.

25 PERICARDIAL EFFUSIONS The classic finding on a chest radiograph is an enlarged cardiac silhouette, the so-called water-bottle heart. However, if the fluid accumulates rapidly, then minimal cardiomegaly may be present. Other potential findings include pleural effusion and rarely pericardial calcifications.

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27 ACUTE RESPIRATORY DISTRESS SYNDROME ARDS defined by the American/European Consensus Committee, as acute and persistent severe hypoxia, bilateral radiographic lung infiltrates, no evidence of congestive heart failure. Patients with lesser degrees of hypoxia are classified as having acute lung injury.

28 ACUTE RESPIRATORY DISTRESS SYNDROME ARDS is not a disease but a syndrome that may be due to direct parenchymal injury (trauma, pneumonia, aspiration) or due to capillary leak oedema from systemic inflammation (sepsis, hypotension) The clinical approach to and radiographic understanding of ARDS has assumed that the type of underlying injury was not relevant to life support strategies and imaging interpretation. Recent evidence suggests that lung mechanics and radiographic appearance may be different in those with ARDS due to pulmonary causes (ARDSp) and those with ARDS due to extrapulmonary causes.

29 THE CLASSICAL RADIOGRAPHIC DESCRIPTIONS OF ARDS During the first hours after a systemic insult, the chest radiograph is normal or it shows mild generalized atelectasis. Over the next 48 hours, there is a rapid increase in density throughout the lungs and often diffuse groundglass to alveolar consolidation symmetrically distributed. The appearance then stabilizes for several days. Toward the end of the first week, the consolidation becomes less dense, eventually forming a fibrotic pattern.

30 ACUTE RESPIRATORY DISTRESS SYNDROME The classical radiographic descriptions of ARDS are as follows: During the first hours after a systemic insult, the chest radiograph is normal or it shows mild generalized atelectasis. Over the next 48 hours, there is a rapid increase in density throughout the lungs and often diffuse ground-glass to alveolar consolidation symmetrically distributed. The appearance then stabilizes for several days. Toward the end of the first week, the consolidation becomes less dense, eventually forming a fibrotic pattern.

31 CT shows bilateral diffuse ground-glass opacification of ARDS due to sepsis. There is also pneumomediastinum due to barotrauma CT shows asymmetrical consolidation from ARDS due to bacterial pneumonia

32 ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS) The most common findings on chest radiographs are bilateral, predominately peripheral, asymmetric consolidations with air bronchograms. Septal lines and pleural effusions are uncommon findings. Early findings during the exudative phase are bilateral consolidations that obscure the pulmonary vascular markings. These opacities extend to more extensive diffuse consolidations that are typically asymmetric. Most radiographic abnormalities begin to resolve after days if the patient survives.

33 CONGESTIVE HEART FAILURE Congestive heart failure is a clinical syndrome in which the heart fails to adequately pump blood to tissues. A number of typical findings may be present on a chest radiograph: With cardiomegaly, the cardiothoracic ratio increases to greater than 50% on a posterior-anterior chest radiograph. Kerley B lines may be present on the lung periphery that are the result of interlobular septal thickening. Accumulated pleural fluid may blunt costophrenic angles or cause large pleural effusions.

34 With cardiomegaly, the cardiothoracic ratio increases to greater than 50% on a posterior-anterior chest radiograph.

35 Kerley B lines may be present on the lung periphery that are the result of interlobular septal thickening.

36 Accumulated pleural fluid may blunt the costophrenic angles or cause large pleural effusions.

37 Pulmonary edema may cause bilateral increased lung markings in a perihilar, or bat-winged, distribution. Increased pulmonary capillary pressure causes the upper lobe vessels to be equal or larger in caliber than the lower lobe vessels, referred to as cephalization.

38 PULMONARY OEDEMA Abnormal accumulation of fluid in the interstitial compartment of the lung with or without associated airspace filling. The oedema is due to changes in hydrostatic forces in the capillaries, to increased capillary permeability or to impaired lymphatic drainage. Transudative pulmonary oedema is due to increased hydrostatic pressure or, rarely, due to decreased oncotic pressure across a functioning capillary membrane. Hydrostatic pulmonary oedema can result from cardiogenic or noncardiogenic (renal failure, fluid overload) causes. Cardiogenic pulmonary oedema is a consequence of elevated left-sided pressure which may result from left ventricular dysfunction, mitral valve disease, left atrial disease or, rarely, pulmonary venous obstruction.

39 PULMONARY OEDEMA The radiographic changes of hydrostatic oedema are quite characteristic. "cephalization" with the upper lobe vessels becoming larger than the lower lobe vessels In left heart failure, the artery enlarges relative to the bronchus. Since they are in the same plane, magnification is not an issue.

40 PULMONARY OEDEMA The upper lobe pulmonary vessels are enlarged. Peribronchial cuffing is seen in the anterior segmental bronchus of the left upper lobe. There is a moderate right pleural effusion in the major and minor fissures. There is a moderate subpulmonary effusion on the left.

41 PULMONARY OEDEMA Posteroanterior radiograph of a 14-year-old child with an acute cardiomyopathy. The airspace shadowing, which is more severe on the right, is typical of pulmonary oedema.

42 PULMONARY OEDEMA The radiograph in cardiogenic pulmonary oedema may show cardiomegaly, alteration of cardiac contour due to congenital heart disease or abnormality of the pulmonary vasculature due to a right-to-left shunt. The earliest radiographic change visible in increased pulmonary venous pressure is redistribution of blood flow, with an increase in prominence of the normally smaller upper lobe vessels. Also, the supine film does not allow detection of any change in distribution.

43 PULMONARY OEDEMA cardiogenic pulmonary oedema

44 THORACIC AORTIC ANEURYSMS Thoracic aortic aneurysms are defined as a greater than 50% aneurysmal dilatation of normal ascending thoracic aorta, aortic arch, or descending thoracic aorta. The descending thoracic aorta is the most common site.

45 THORACIC AORTIC ANEURYSMS On chest radiographs, the most common findings are a widening of the mediastinal silhouette (white arrow), enlargement of the aortic knob and tracheal displacement (red arrow). Other radiographic findings include a double-opacity appearance to the aorta representing true and false lumens, localized bulges along the aortic contour and a disparity in the caliber of the descending and ascending aorta.

46 THORACIC AORTIC ANEURYSMS

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48 AORTIC DISSECTION Splitting of the media of the aortic wall by blood. It may occur by means of a tear in the aortic intima with blood passing from the lumen into the wall causing the intima to be torn from the wall for a variable distance. Dissection may also occur by spontaneous bleeding of the vasa vasorum causing intramural haematoma without rupture of the intima and consequently no connection between the lumen and the intramural dissection.

49 AORTIC DISSECTION Degeneration of the aortic media, cystic medial necrosis, is the pathological substrate for aortic dissection. This may be induced by chronic stress against the wall such as occurs with systemic hypertension, aortic coarctation, aortic stenosis and bicuspid aortic valve. Cystic medial necrosis is a feature of hereditary defects of connective tissue, especially Marfans syndrome and Ehlers Danlos syndrome. The risk of dissection is increased during pregnancy.

50 AORTIC DISSECTION There are two classifications of aortic dissection. The Stanford classification recognizes Type A (involvement of ascending aorta alone or involvement of ascending and descending aorta) and Type B (involvement of descending aorta alone). The De Bakey classification describes Type I (ascending and descending aorta), Type II (ascending aorta alone) and Type III (descending aorta only). Stanford A and De Bakey I and II are treated by emergency surgery.

51 AORTIC DISSECTION Diagram showing the two classification systems. Stanford Type A includes DeBakey Type I and II

52 AORTIC DISSECTION - IMAGING The chest X-ray is neither sensitive nor specific for establishing the diagnosis of aortic dissection. The chest radiograph frequently demonstrates an enlarged thoracic aorta as a consequence of underlying predisposing diseases such as hypertension or aortic valvular disease. The chest X-ray may display features indicative of Marfans syndrome such as sternal deformity, scoliosis and elongated thorax. Infrequently, the chest X-ray may demonstrate inward displacement of intimal calcification in the aortic arch on the frontal view or an apical pleural cap.

53 THE DEFINITIVE DIAGNOSIS OF AORTIC DISSECTION CAN BE ESTABLISHED BY: thoracic aortography, computed tomography angiograhy, magnetic resonance imaging angiograhy, echocardiography.

54 AORTIC DISSECTION - IMAGING The goals of imaging studies in the typical dissection are to identify: the intimal flap; extent of the dissection; involvement of aortic branches; patency of the false channel; periaortic hematoma or haemorrhagic pericardial effusion; aortic regurgitation.

55 AORTIC DISSECTION

56 AORTIC DISSECTION Partition of a three-dimensional contrastenhanced MRA shows intimal flap (arrows) in the distal aortic arch and descending aorta.

57 AORTIC DISSECTION CT angiography, and MR angiography are highly sensitive and specific for the diagnosis of aortic dissection. They display the presence and extent of the intimal flap and the sizes and configurations of the true and false channels. Because of limitations in acquiring diagnostic images in some subjects and lower diagnostic accuracy, transthoracic echocardiography has been replaced by transoesophageal echocardiography. The portability of transoesophageal echocardiography is a highly attractive attribute since it can be taken to the patient in the emergency department or intensive care unit.

58 PULMONARY EMBOLISM (PE) Embolic occlusion of the pulmonary arterial system. The majority of cases result from thrombotic occlusion and therefore the condition is frequently termed pulmonary thrombo-embolism Clinical signs and symptoms are non-specific. Dyspnoea, chest pain, and haemoptysis have been described as a classic triad in pulmonary embolism. 2 scores: Wells score, Geneva score. Markers: D-dimer (normal D-dimer has almost 100% negative predictive value (virtually excludes PE): no further testing is required. Raised D-dimer is caused by many other diseases than PE = Raised D Dimer is non-specific: it indicates the need for further testing if pulmonary embolism is suspected)!

59 PULMONARY EMBOLISM (PE) Risk factors primary hypercoagulable states (protein C or S deficency, antithrombin III deficiency) recent surgery pregnancy prolonged bed rest / immobility malignancy oral contraceptive use

60 PLAIN RADIOGRAPH Fleishner sign: enlarged pulmonary artery (20%)

61 Hampton hump: peripheral wedge of airspace opacity and implies lung infarction (20%) PLAIN RADIOGRAPH

62 PLAIN RADIOGRAPH Westermark's sign: focal peripheral hyperlucency secondary to focal hypovolemia pleural effusion (35%) elevated diaphragm

63 CT PULMONARY ANGIOGRAPHY (CTPA) shows filling defects within pulmonary vasculature with acute pulmonary emboli

64 CT PULMONARY ANGIOGRAPHY (CTPA) shows filling defects within pulmonary vasculature with acute pulmonary emboli

65 VQ scan will show ventilationperfusion mismatches. NUCLEAR MEDICINE

66 MRI???

67 MR findings for acute PE were similar to those seen by CT or angiography, because all provided morphological representations of the same pathological process. We classified the MR features of pulmonary thromboembolism as vascular signs or parenchymal sign: Pulmonary arterial signs Signs of pulmonary hypertension Collateral systemic supply Parenchymal signs A meta-analysis of studies that adopted gadoliniumenhanced MR for imaging acute PE used conventional pulmonary angiography as the reference standard. A broad range of sensitivities, from 77% to 100%, was reported, with uniformly high specificities of 95% to 98%. Hochhegger B, Ley-Zaporozhan J, Marchiori E, et al. Magnetic resonance imaging findings in acute pulmonary embolism. The British Journal of Radiology. 2011;84(999): doi: /bjr/

68 DIAPHRAGMATIC HERNIAS Diaphragmatic hernias are caused when a defect in the diaphragmatic wall allows for the herniation of abdominal contents into the thoracic cavity. The majority of tears are on the left side and are thought to represent either weakness of the left hemidiaphragm or protection by the liver.

69 DIAPHRAGMATIC HERNIAS On chest radiographs, asymmetry of hemidiaphragm or changing diaphragmatic levels may be present (arrows). Gas-filled organs or a nasogastric tube within thoracic cavity will confirm the diagnosis. Solid abdominal organs will appear as mushroom-shaped homogeneous opacities. Potential misdiagnosis can occur in the case of diaphragmatic paralysis or after lung reduction surgery.

70 HEMITHORAX WHITE-OUT Complete white-out of a hemithorax on the chest x-ray has a limited number of causes. The differential diagnosis can be shortened further with one simple observation - the position of trachea. Is it central, pulled or pushed from the side of opacification?

71 TRACHEA PULLED TOWARD THE OPACIFIED SIDE Pneumonectomy total lung collapse: e.g. endobronchial intubation pulmonary agenesis pulmonary hypoplasia

72 TRACHEA PULLED TOWARD THE OPACIFIED SIDE Pneumonectomy total lung collapse: e.g. endobronchial intubation pulmonary agenesis pulmonary hypoplasia

73 TRACHEA REMAINS CENTRAL IN POSITION Consolidation pulmonary oedema/ards pleural mass: e.g. mesothelioma chest wall mass: e.g. Askin/Ewing sarcoma

74 PUSHED AWAY FROM THE OPACIFIED SIDE pleural effusion diaphragmatic hernia large pulmonary mass

75 Pneumoperitoneum

76 Pneumoperitoneum refers to air within the peritoneal cavity, most commonly from perforation of an abdominal viscus. Air will accumulate in the least dependent portion of abdominal cavity. During upright chest radiographs, air will separate liver, spleen and intestines from diaphragm producing dark crescents. To ensure adequate air migration, patients should be kept upright for at least 5 minutes before the image is taken.

77 THANKS FOR ATTENTION

78 THANKS FOR ATTENTION Hochhegger B, Ley-Zaporozhan J, Marchiori E, et al. Magnetic resonance imaging findings in acute pulmonary embolism. The British Journal of Radiology. 2011;84(999): doi: /bjr/ Oikonomou A, Prassopoulos P. CT imaging of blunt chest trauma. Insights into Imaging. 2011;2(3): doi: /s ECR 2008 / C-275Blunt chest trauma: Spectrum of findings with emphasis on MDCT