Pulmonology/Critical Care Flashcards
Cystic lung diseases - Five most common causes
Five most common causes: 1. Lymphangioleiomyomatosis (LAM) 2. Pulmonary Langerhans cell histiocytosis (PLCH) 3. Lymphoid interstitial pneumonia (LIP, associated with Sjögren syndrome) 4. Birt-Hogg-Dubé syndrome (BHD) 5. Pneumocystis jiroveci pneumonia (PJP) Other causes: - Desquamative interstitial pneumonia (DIP) - Amyloidosis - Light chain deposition disease (LCDD) - Papillomatosis
Cystic lung diseases - What are lung cysts - Mimics of lung cysts
Lung cysts: Round, circumscribed space surrounded by epithelial or fibrous wall (wall<2mm), usually filled with air - Bleb ≤1 cm - Bulla >1 cm Mimics of lung cysts - emphysema - honeycombing - cavities - cystic bronchiectasis
Lymphangioleiomyomatosis (LAM) - Pathogenesis - Clinical Features (demographics, imaging, histopathology) - Treatment
Pathogenesis: - mutations in TSC1 and TSC2 genes - sporadic or associated with tuberous sclerosis Features: - Women of childbearing age - Symptoms: pneumothorax, DOE, hemoptysis, wheezing, chylous pleural effusion, ascites - Imaging: thin-walled, multiple, diffuse throughout the lungs with no lobar predominance, smaller sized (2-5 mm), lung parenchyma usually normal - Histopathology: nodules/clusters of smooth muscle cells near cysts as well as terminal bronchioles, alveolar walls, blood vessels, and lymphatics - Extrathoracic: renal and hepatic angiomyolipoma, meningioma Treatment: - Avoid estrogen - Sirolimus (activation of mTOR on pathway of TSC mutations) - Lung transplant
Pulmonary Langerhans cell histiocytosis (PLCH) - Clinical features (demographics, imaging, histopathology, extrathoracic)
Clinical features: - smokers in 20s-30s, M=F - imaging: nodules cavitate causing thick-walled cysts which can coalesce - histopathology: peribronchiolar infiltration of Langerhans cells -> granulomas -> nodules - extrathoracic: bone lesions, diabetes insipidus, skin lesions
What is hypersensitivity pneumonitis?
Complex syndrome of varying intensity and clinical presentation. Immunologic reaction to an inhaled agent occuring within the lung parenchyma. There are numerous inciting agents; bacteria/mycobacteria, fungi or molds, proteins, chemicals.
What is the diagnostic criteria for hypersensitivity pneumonitis?
Need 3 of the following 5 criteria to make the diagnosis;
- Known exposure to offending antigen
- Compatible clinical, radiographic, or physiologic findings
- BAL showing lymphocytosis
- Positive inhalation challenge testing
- Histopathology; poorly formed, noncaseating granulomas or mononuclear cell infiltration of alveolar walls.
What is the treatment for hypersensitivity pneumonitis?
Antigen avodiance (if known).
Glucocorticoids; start at 0.5 mg/kg to 1 mg/kg for two weeks, then taper over 2-4 weeks.
What is the criteria needed to diagnose ARDS?
Bilateral opacities consistent with pulmonary edema on chest radiograph or chest CT, onset occurs within 7 days of known clinical insult or new/worsening respiratory symptoms.
How do you categorize ARDS severity?
Mild; PaO2:FiO2 201-300 mm Hg
Moderate PaO2:FiO2; 101-200 mmg Hg
Severe; PaO2:FiO2 < 100 mm Hg
How do you treat ARDS?
Try to identify and treat underlyin conditions.
Conservative fluid therapy.
Ventilation parameters 6 mL/kg PDW with Plateau pressures less 30.
What is Light’s crieria?
An exudate meets 1 of 3 criteria;
- (Pleural Fluid Protein)/(Serum Protein)>0.5
- (Pleural Fluid LDH)/(Serum LDH)>0.6
- Pleural Fluid LDH >2/3 ULN of serum LDH
What is the definition of an uncomplicated parapneumonic effusion?
Lung interstitial fluid increases during pneumonia and moves across the adjacent visceral pleural membrane.
What is the definition of a complicated parapneumonic effusion?
Bacterial invasion of the pleural space. However
As evident by:
- Increased neutrophils
- Development of pleural fluid acidosis
- Anaerobic utilization of glucose by neutrophils and PMNs
- High LDH – lysis of neutrophils
- Deposition of dense layer of fibrin that can lead to pleural loculation
- Cultures are usually sterile as bacteria are cleared rapidly, but fluid will be cloudy.
What is the definition of a thoracic empyema?
Pus or presence of bacterial organisms on Gram stain
A positive culture is NOT required for diagnosis due to the following reasons:
- Anaerobic organisms may be difficult to culture
- Sampling often performed after receiving antibiotics
- Sterile inflammatory fluid may be aspirated adjacent to an infected loculus of infection
- Culture methods are insufficiently sensitive
What is the clinical presentation of a parapneumonic effusion?
- Cough, fever, pleuritic chest pain, dyspnea, sputum production.
- Exam will show decreaed breath sounds, decreased fremitus, dullness to percussion.
- CXR will show a pleural based opacity.
- If suspect a loculated effusion, then order a CT with IV Constrast.
