Podcast
Questions and Answers
Which of the following is a cause of primary ARDS?
Which of the following is a cause of primary ARDS?
The fibrotic vasoconstriction phase occurs between 14-21 days after the onset of ARDS.
The fibrotic vasoconstriction phase occurs between 14-21 days after the onset of ARDS.
True
What is the hallmark of the acute exudative phase of ARDS?
What is the hallmark of the acute exudative phase of ARDS?
Eosinophilic hyaline membrane deposition
The loss of surfactant in ARDS leads to __________ of the alveoli.
The loss of surfactant in ARDS leads to __________ of the alveoli.
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Match the following phases of ARDS with their descriptions:
Match the following phases of ARDS with their descriptions:
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Which of the following conditions is NOT prone to develop interstitial lung disease (ILD)?
Which of the following conditions is NOT prone to develop interstitial lung disease (ILD)?
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Blameycin is known to be a drug that can induce interstitial lung disease.
Blameycin is known to be a drug that can induce interstitial lung disease.
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What pattern of ILD is most common in rheumatoid arthritis?
What pattern of ILD is most common in rheumatoid arthritis?
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Eosinophilic granulomatosis polyangiitis is associated with ___ lobe ILD.
Eosinophilic granulomatosis polyangiitis is associated with ___ lobe ILD.
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Match the following ILD types with their characteristics:
Match the following ILD types with their characteristics:
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What does elevated $P_{aCO_2}$ indicate in the diagnosis of respiratory failure?
What does elevated $P_{aCO_2}$ indicate in the diagnosis of respiratory failure?
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A V/Q ratio of infinity indicates a shunt.
A V/Q ratio of infinity indicates a shunt.
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What should be evaluated when there is an elevated $P_{aO_2}$?
What should be evaluated when there is an elevated $P_{aO_2}$?
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If the patient is hypoventilating and the $P_{O_2}$ is low and corrected with oxygen, this may indicate _____ altitude.
If the patient is hypoventilating and the $P_{O_2}$ is low and corrected with oxygen, this may indicate _____ altitude.
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Match the hypoventilation types with their corresponding indicators:
Match the hypoventilation types with their corresponding indicators:
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Which of the following is a symptom specific to bronchiectasis?
Which of the following is a symptom specific to bronchiectasis?
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Hypoxia is a common sign of ILD.
Hypoxia is a common sign of ILD.
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What is the most significant factor for prognosis in ILD?
What is the most significant factor for prognosis in ILD?
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CXR findings in ILD typically display bilateral bibasal __________ infiltrates.
CXR findings in ILD typically display bilateral bibasal __________ infiltrates.
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Match the following conditions with their corresponding features:
Match the following conditions with their corresponding features:
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What is the typical V/Q ratio in healthy lungs?
What is the typical V/Q ratio in healthy lungs?
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A patient with type III respiratory failure has decreased functional residual capacity.
A patient with type III respiratory failure has decreased functional residual capacity.
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List two common etiologies of type III respiratory failure.
List two common etiologies of type III respiratory failure.
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In type III respiratory failure, the pathology includes decreased functional residual capacity, which is comprised of residual volume and _______.
In type III respiratory failure, the pathology includes decreased functional residual capacity, which is comprised of residual volume and _______.
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Match the type of respiratory failure with its characteristic features:
Match the type of respiratory failure with its characteristic features:
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What imaging technique is primarily used to determine the pattern and prognosis of interstitial lung disease?
What imaging technique is primarily used to determine the pattern and prognosis of interstitial lung disease?
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Ground glass opacification is a feature that may be present in Usual Interstitial Pneumonia (UIP).
Ground glass opacification is a feature that may be present in Usual Interstitial Pneumonia (UIP).
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What pulmonary function test finding is associated with the initial phase of interstitial lung disease?
What pulmonary function test finding is associated with the initial phase of interstitial lung disease?
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Traction bronchiectasis is a finding associated with ________________.
Traction bronchiectasis is a finding associated with ________________.
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Match the following drugs with their action in treating UIP-ILD:
Match the following drugs with their action in treating UIP-ILD:
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What does the abbreviation DAD stand for in the context of lung injury?
What does the abbreviation DAD stand for in the context of lung injury?
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The pulmonary capillary wedge pressure (PCWP) is used to measure right atrial pressure.
The pulmonary capillary wedge pressure (PCWP) is used to measure right atrial pressure.
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What is one significant indicator of non-cardiogenic pulmonary edema?
What is one significant indicator of non-cardiogenic pulmonary edema?
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The condition recognized by terms such as shock lung and acute alveolar injury is known as __________.
The condition recognized by terms such as shock lung and acute alveolar injury is known as __________.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Which of the following is NOT characteristic of Non-Specific Interstitial Pneumonia (NSIP)?
Which of the following is NOT characteristic of Non-Specific Interstitial Pneumonia (NSIP)?
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Amiodarone can cause interstitial lung disease with an NSIP pattern.
Amiodarone can cause interstitial lung disease with an NSIP pattern.
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What is the best treatment for Non-Specific Interstitial Pneumonia (NSIP)?
What is the best treatment for Non-Specific Interstitial Pneumonia (NSIP)?
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In Bronchiolitis Obliterans Organising Pneumonia, the presence of polypoid plugs is referred to as __________.
In Bronchiolitis Obliterans Organising Pneumonia, the presence of polypoid plugs is referred to as __________.
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Match the following lung conditions with their primary associations:
Match the following lung conditions with their primary associations:
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Which symptom is NOT typically associated with acute respiratory distress syndrome (ARDS)?
Which symptom is NOT typically associated with acute respiratory distress syndrome (ARDS)?
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Mechanical ventilation is considered the mainstay of treatment for respiratory failure.
Mechanical ventilation is considered the mainstay of treatment for respiratory failure.
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Which of the following is the most common type of idiopathic interstitial pneumonia?
Which of the following is the most common type of idiopathic interstitial pneumonia?
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What are bilateral crackles indicative of in patients with respiratory distress?
What are bilateral crackles indicative of in patients with respiratory distress?
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Sarcoidosis is classified as a type of idiopathic interstitial pneumonia.
Sarcoidosis is classified as a type of idiopathic interstitial pneumonia.
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In VILI, high positive end expiratory pressure (PEEP) is used to treat _________.
In VILI, high positive end expiratory pressure (PEEP) is used to treat _________.
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What is the primary pathogenic fibrogenic cytokine associated with interstitial lung disease?
What is the primary pathogenic fibrogenic cytokine associated with interstitial lung disease?
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Match the following conditions with their differential diagnoses of acute breathlessness:
Match the following conditions with their differential diagnoses of acute breathlessness:
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The connective tissue that holds the lungs together is called the __________.
The connective tissue that holds the lungs together is called the __________.
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Match the following types of interstitial lung disease with their characteristics:
Match the following types of interstitial lung disease with their characteristics:
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Study Notes
Etiology of ARDS
- Primary ARDS: caused by conditions directly affecting the lungs, including pulmonary sepsis, massive blood transfusion, acute pancreatitis, and transfusion-associated lung injury (TRALI)
- Secondary ARDS: caused by conditions outside the lungs, such as smoke inhalation, drowning, post-surgery complications, non-pulmonary sepsis, and major trauma or burns
Pathogenesis of ARDS
- Alveolar epithelial injury: initiated by toxins, sepsis, or other insults
- Inflammatory mediators: release of interleukin-1 (IL-1), IL-6, tumor necrosis factor-alpha (TNF-α), and other cytokines
- Neutrophil recruitment: attraction of neutrophils to the injured area
- Exudation: accumulation of proteinaceous fluid and debris in the alveolar space
- Surfactant loss: reduced surfactant production leads to alveolar collapse
- Impaired gas exchange: decreased lung compliance results in ineffective gas exchange
- Capillary endothelial injury: damage to the blood vessels in the lungs
Respiratory Failure Diagnostic Flowchart
- Elevated PaCO2P_{aCO_2}PaCO2: indicates hypercapnic respiratory failure, requiring further investigation
-
Elevated PaO2P_{aO_2}PaO2 - PaO2P_{aO_2}PaO2: suggests V/Q mismatch or shunting
- V/Q = 0: Shunt (e.g., problem in blood flow)
- V/Q = ∞: Dead space (e.g., problem in ventilation)
-
Hypoventilation: indicates a problem with breathing mechanics, further classification needed
- Type II Hypoventilation: PO2P_{O_2}PO2 low but correctable with oxygen, may be due to high altitude or other underlying mechanisms
- Type I Hypoventilation: other hypoventilation mechanisms
- V/Q mismatch: further analysis required to determine the underlying cause
Autoimmune ILD
- ILD can develop in individuals with autoimmune conditions:
- Rheumatoid arthritis
- Diffuse systemic sclerosis
- Polymyositis/dermatomyositis
- Mixed connective tissue disease (MCTD)
- Sjogren's syndrome
- Ankylosing spondylitis
Miscellaneous ILDs
-
Occupational ILDs:
- Asbestosis: lower lobe ILD
- Silicosis
- Berylliosis
- Coal-worker’s pneumoconiosis
-
Vasculitis-related ILD:
- Eosinophilic granulomatosis polyangiitis (EGPA)/Churg-Strauss syndrome: upper lobe ILD
-
Inherited forms of ILD:
- Neurofibromatosis
- Tuberous sclerosis
-
Drug-induced ILD:
- Bleomycin
- Langerhan’s cell histiocytosis (LCH): Associated with smoking.
- Lymphangiomyomatosis (LAM):
Key Characteristics of ILD Patterns
-
UIP/IPF:
- Idiopathic
- Males > females
- Age: 50-70 years
- Associated with smoking
-
NSIP:
- Young females
- Subacute restrictive process
- Associations: Drug, Connective tissue disease
-
COP:
- Most common in inflammatory muscle disease: Polymyositis, Dermatomyositis
-
LIP:
- Associated with Sjogren syndrome and HIV
Clinical Features of ILD
-
Symptoms:
- Dry, non-productive cough
- Dyspnea on exertion
- Fever and arthralgia (Sarcoidosis)
- Wheezing (Bronchiectasis)
- Pleuritic pain (Asbestosis)
- Hemoptysis (Rare)
-
Signs:
-
Auscultation:
- ILD: Bilateral bibasal, fine “velcro crackles” at the end of expiration
- Bronchiectasis: Unilateral, coarse crackles heard early in inspiration
-
Other:
- Cafe-au-lait spots (Neurofibromatosis)
- Erythema nodosum (Sarcoidosis)
- Raynaud's phenomenon (Scleroderma)
- Hypoxia
-
Auscultation:
Investigations for ILD
- CXR: Bilateral bibasal subpleural reticular/reticulo-nodular infiltrates
- HRCT: Investigation of choice to determine pattern and prognosis of ILD
The Interstitium
- Connective tissue that holds the lungs together, including alveolar, subpleural, lobar, vascular, axial, and lung parenchyma
ILD Classification
- Idiopathic Interstitial Pneumonia (most common)
- Autoimmune ILD
- Hypersensitivity pneumonitis
- Sarcoidosis
- Miscellaneous
Idiopathic Interstitial Pneumonia Types
- Idiopathic pulmonary fibrosis/usual interstitial pneumonia (UIP): Most common
- Idiopathic nonspecific interstitial pneumonia (NSIP):
- Cryptogenic organizing pneumonia (COP): Third most common
- Respiratory bronchiolitis interstitial lung disease (RB-ILD)
- Desquamative interstitial pneumonia (DIP)
- Acute interstitial pneumonia:
- Lymphocytic interstitial pneumonia (LIP)
Type 3 Respiratory Failure
- Pathology: Decreased Functional Residual Capacity (Residual volume + Expiratory Reserve Volume)
-
Etiology:
- Supine position, obesity, ascites
- Residual effects of anesthesia
- Upper abdominal incision
- Airway secretions
- Collapse (Post op Atelectasis)
Hypoxemic Respiratory Failure - V/Q Matching
- Normal V/Q Ratio: 0.8
- Upper Zone: >1 (Non-dependent area → ↓v, ↓↓Q)
- Lower Zone: <1 (Dependent area → ↑v, ↓Q)
Clinical Features of ARDS
- Rapid onset dyspnea
- Hypoxemia
- Bilateral crackles
- Tachypnea, tachycardia, diaphoresis
- Pulmonary hypertension
ARDS Management
- Mechanical ventilation:
- Inverse ratio ventilation
- Prone ventilation
- Permissive hypercapnia
VILI (Ventilation Induced Lung Injury)
-
Pathogenesis:
- Volume Trauma: Increased lung volume
- Barotrauma: Increased transpulmonary pressure
- Atelectrauma: Collapse and decollapse of alveoli during breathing
-
Treatment:
- Low tidal volume ventilation
- Low plateau pressure
- High positive end expiratory pressure (PEEP)
Differential Diagnosis of Acute Breathlessness
-
Respiratory:
- Pulmonary edema
- Pulmonary embolism
- Pneumothorax
- Acute exacerbation of asthma
-
Cardiovascular:
- Aortic dissection
- Myocardial infarction
PFT Findings in ILD
- Initial Phase: Impaired DLCO (Diffusion capacity of lung for carbon monoxide); Normal FEV (Forced Expiratory Volume in 1 second); FVC (Forced Vital Capacity)
- Advanced Disease: Reduced FVC; Normal or increased FEV/FVC ratio
HRCT Findings in ILD
-
UIP:
-
Suggestive Features:
- Linear shadows (Intralobular septal thickening)
- Reticular shadows (Net of linear opacities)
- Subpleural, basal predominant
- Honeycombing (Small, polyhedral cystic spaces)
- Loss of lung architecture
- Traction bronchiectasis
- Nodules
-
Absent Features:
- Ground glass opacification
-
Suggestive Features:
-
Other Findings:
- Honeycombing
- Reticular shadows
- Linear shadows
- Traction bronchiectasis
-
New Drugs for UIP-ILD:
- Pirfenidone (Anti-TGF)
- Nintedanib (Anti-FDGF, anti VEGF, anti PDGFR)
Characteristics of NSIP
- B/L posterior-basal ground-glass appearance
- No destruction of lung parenchyma
- No honeycombing
- No cystic spaces
- Prognosis: NSIP > UIP
Drugs Causing ILD (NSIP Pattern)
- Amiodarone
- Bleomycin
- Busulfan
- Bromocriptine
- Nitrofurantoin
- Cyclophosphamide
- Methotrexate
- Anti-TNF
- Carmustine
- Mitomycin
Treatment of NSIP
- MMF (best)
- Steroids
- Azathioprine
Features of COP/BOOP
- Elderly males (>60-70 years)
- Polypoid plugs in bronchioles (Masson's buds)
- Pneumonia-like presentation
- Associations: Polymyositis/Dermatomyositis
-
HRCT: Consolidations (Peribronchial, perilobar opacities)
- Reverse-halo sign: Ground glass opacification (GGO) surrounded by consolidation
- Types: Restrictive, Constrictive
Different Cystic Appearances on HRCT
- LAM: Young females, association with tuberous sclerosis and angiomyolipoma; Complications: Spontaneous pneumothorax, Chylous effusion; Treatment: Everolimus (mTOR inhibitor)
- LCH: Young males, upper lobe fibrosis; Complications: Spontaneous pneumothorax; Pathology: CDIA (+), Birbeck granules (+); Associations: Smoking, Lytic lesions, Diabetes insipidus
- LIP: Associated with Sjogren's and HIV
AECC Criteria for ARDS
-
Non-cardiogenic pulmonary edema:
- Pulmonary capillary wedge pressure (PCWP) <18 mmHg
- Bilateral infiltrates on CXR
- PaO2/FiO2 ≤ 200 mmHg
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Description
This quiz explores the etiology and pathogenesis of Acute Respiratory Distress Syndrome (ARDS). It covers both primary and secondary causes, the mechanism of alveolar injury, and the role of inflammatory mediators. Test your knowledge on the complexities of ARDS and its impact on lung function.
