Lecture 9: Pleural and Mediastinal Diseases Flashcards
What are the 3 leading causes of pleural effusion in the US?
- Heart failure
- Pneumonia
- Cancer
What is the most common finding auscultated over a pleural effusion; and what is auscultated toward the top of an effusion?
- Decreased to absent breath sounds over an effusion
- Bronchial breath sounds toward the top of an effusion
Which imaging study is usually the first study used to identify and quantify the amount of fluid seen with a pleural effusion?
CXR
How much pleural fluid is needed to blunt the costophrenic angle on plain CXR?
~250 mL
Which sign is created as greater amounts of fluid with a pleural effusion opacify the lower thorax?
“Meniscus sign”
After the presence of a pleural effusion is documented what study is used to evaluate whether an effusion is free-flowing or loculated (non-free flowing) and whether a sufficient quantity is present to perform thoracentesis?
Decubitus films
How much distance measured from the pleural fluid line to the chest wall on a decubitus radiograph is indicative of adequate pleural fluid to perform thoracentesis?
1-cm distance
Which imaging modality is highly sensitive for pulmonary embolism and may be indicated if the pretest probability of pulmonary embolism is moderate to high?
Spiral chest CT
Which imaging modality can be used to detect loculations, guide thoracentesis of a pleural effusion, and detect pleural abnormalities not apparent on CXR?
Ultrasound
Bilateral transudative pleural effusions are commonly associated with what underlying diseases?
Heart or liver failure
Bilatral exudative pleural effusions suggest what underlying disease(s)?
Malignancy, but may aso occur in pt’s w/ pleuritis due to SLE and other collagen vascular disorders
Caution is advised when performing thoacentesis in which pt’s?
Those w/ severe coagulopathy, thrombocytopenia, hemodynamic compromise, or on mechanical ventilation
What is the major complication of thoracentesis?
Pneumothorax
Gross pus in the pleural space is diagnostic of what?
Empyema
If TB is suspected on clinical presentation w/ pleural effusion which 3 diagnostic studies can be used as adjuncts to diagnosis?
- Lymphocytic predominance on leukocyte count
- Adenosine deaminase activity
- PCR
An increased lymphocytic effusion (>50%) is most often due to what 2 etiologies?
- Malignancy
- TB
Transudates are associated with a pleural fluid pH in what range (normal = 7.6 to 7.66)?
7.45 to 7.55
Pleural fluid amylase should be measured only when what 3 causes are being considered?
- Pancreatic disease
- Esophageal rupture
- Malignancy
What are 5 underlying causes of a low pleural glucose?
- Parapneumonic effusion
- Malignant effusion
- Tuberculosis
- Hemothorax
- Rheumatoid Arthritis
Increased eosinophils (>10%) within the pleural space most often due to what?
Air in the pleural space
2 major causes of transudative pleural effusion and what are 3 other less common causes?
- Major = LVF or CHF
- Other = misplaced central line; massive cirrhosis; nephrosis
Which ratio of pleural protein/serum protein suggests the presence of an exudative vs. transudative pleural effusion?
- Exudative = pleural protein/serum protein >0.5
- Transudative = <0.5
Which ratio of pleural fluid LDH to serum LDH is suggestive of exudative vs. transudative pleural effusion?
- Exudative = pleural LDH/serum LDH >0.6
- Transudative = pleural LDH/serum LDH <0.6
Which findings of pleural fluid LDH compared to the upper limit of normal for serum is suggestive of exudative vs. transudative effusion?
- Exudative = >2/3 upper limit of normal for serum
- Transudative = <2/3 upper limit of normal for serum
Which type of effusion is associated with a low leukocyte count vs. high leukocyte count?
- Transudative effusions typically have a low leukocyte count (<1000/uL)
- Pleural leukocyte count >10,000 uL is most likely due to parapneumonic effusion; pancreatitis; splenic infarction; andsubphrenic, hepatic, andsplenic abscesses
A pleural leukocyte count >50,000/uL is always associated with what?
Complicated parapneumonic effusions and empyema
When malignancy is suspected but intitial thoracentesis is non-diagnostic, what is the next step?
Cytologic evaluation of a second, large-voume pleural fluid sample
In regards to the sensitivity of pleural fluid cytology, which type of tumor is associated with high positivity and which has low positivity?
- High positivity = Adenocarcinoma
- Low positivity = Hodgkin lymphoma
What is the tx for acute pleural effusions?
- Tx the underlying cause - Abx for pneumonia
- Observation
Therapeutic thoracentesis should be limited to the removal of how much fluid at a time?
NO more than 1.5 L; minimizes likelihood of reexpansion pulmonary ededma
What are 2 options for the mangement of chronc pleural effusions?
- PleurX catheter –> indwelling catheter in pleural space allowing for at-home drainage
- Pleurodesis –> obliteration of the pleural space w/ a chemical agent (i.e., talc, tetracycline, etc.) using a thorascope or in IR
50% of patients with pneumothorax in the setting of recurrent (but not primary) Pneumocystis pneumonia will develop what?
Pneumothorax on the contralateral side
Tension pneumothorax should be suspected in the presence of what signs/sx’s?
- Marked tachycardia
- HYPOtension
- Mediastinal or tracheal shift
Demonstration of what on a chest radiograph is diagnostic of a pneumothorax?
Visceral pleural line
Which characteristic sign may be seen on chest radiograph in supine pt’s presenting with pneumothorax?
“Deep sulcus” sign
What is treatment for reliable pt with a small (<15% of a hemithorax), stable, spontaneous primary pneumothorax?
Observation alone may be appropriate
Which therapy may increase the rate of reabsorption of air associated with a pneumothorax?
Supplemental O2
Placement of what in a pt with pneumothorax can provide protection against development of tensio pneumothorax and may permit observation from home?
Small-bore chest tube attached to one-way Heimlich valve
Observation of pt with pneumothorax should invovle serial CXR’s how often?
Every 24 hours
Pts with secondary pneumothorax, large pneumothorax, tension pneumothorax, severe sx’s, or those with pneumothorax on mechanical ventilation should undergo what tx?
Chest tube placement (tube thoracostomy)
What are indications for a thorascopy or open thoracotomy in pneumothorax pt’s?
- Recurrences of spontaneous pneumothorax
- Any occurrence of bilateral pneumothorax
- Failure of tube thoracostomy for first episode (failure of lung to reexpand or persistent air leak)
What are the differences in percussion in a pneumothorax vs. pleural effusion?
- Hyper-resonance in pneumothorax
- Dull in pleural effusion
What are the positional changes of breath sounds like in a pneumothorax vs. pleural effusion?
- No change in pneumothorax
- May improve in pleural effusion
What 3 major structures are found in the anterior mediastinal compartment?
- Thymus gland
- Anterior mediastinal LN’s
- Internal mammary arteries and veins
Which region of the mediastinum contains the descending thoracic aorta, esophagus, thoracic duct, and the azygos and hemiazygos veins?
Posterior mediastinum
What are the most common lesions of the anterior mediastinum (4 or them - remembered as the “4-T’s”)?
- Thymomas
- “Terrible” (T cell) Lymphomas - can be B cells as well as Hodgkin
- Teratomatous neoplasms
- Thyroid masses
What are the 3 most common masses of the middle mediastinum (remembered VAC)?
- Vascular masses
- Adenopathy from metastases or granulomatous disease
- Cysts - Pleuropericardial and bronchogenic
What are the most common lesions found in the posterior mediastinum?
- Neurogenic tumors
- Meningoceles and meningomyeloceles
- Gastroenteric cysts and esophageal diverticula
What is the most valuable imaging technique for evaluating mediastinal masses and is often the only imaging technique that should be done in most instances?
CT
Which diagnostic studies are indicated in many pt’s with posterior mediastinal lesions, because hernias, diverticula, and achalasia are readily diagnosed in this manner?
Barium studies
Which scan can efficiently establish the diagnosis of intrathoracic goiter (anterior mediastinum)?
iodine-131 scan
Which invasive techniques allow for definitive diagnosis of masses in the anterior or middle mediastinal compartments?
MediastinOSCOPY or anterior mediastinOTOMY
Via what technique can a diagnosis and removal of a mediastinal mass be accomplished?
Video-assisted thoracoscopy
How is the diagnosis of acute mediastinitis following median sternotomy for cardiac surgery made?
Mediastinal needle aspiration
Most cases of chronic mediastinitis are due to what?
Histoplasmosis or TB
What are the 3 main causes of pneumomediastinum?
1) Alveolar rupture w/ dissection of air into the mediastinum
2) Perforation or rupture of the esophagus, trachea, or main bronchi
3) Dissection of air from the neck or the abdomen into the mediastinum
What are signs/sx’s and PE findings indicative of pneumomediastinum?
- Severe substernal chest pain with or w/o radiation into the neck and arms
- PE reveals subcutaneous emphysema in the suprasternal notch and Hamman’s sign, which is crunching or clicking nose synchronouse w/ the heartbeat
Which imaging modality is used for confirming the diagnosis of pneumomediastinum?
CXR
