P- Restrictive Lung Disease & Pulmonary Vascular Disease Flashcards
In restrictive lung disease, the key abnormality is impaired _______________ due to decreased __________ of alveolar septa, resulting in ________total lung capacity while ________ remains normal or reduced proportionately.
Impaired airway filling due to decreased elasticity (due to fibrosis) of the alveolar septa, resulting in reduced TLC while airflow is normal or reduced proportionately.
What are the two main physiological problems caused by interstitial lung disease fibrosis in the interstitium?
- The septa are stiff and limit the inspiratory volume increasing effort for inspiration
- Fibrosis of the alveolar wall decrease gas exchange by increasing distance from alveoli to capillary
What happens to the DLCO and FEV1/FVC in restrictive lung disease?
DLCO decreases while FEV1/FVC remains normal (because they both decrease proportionately)
What is the clinical presentation of adults respiratory distress syndrome?
What is the clinical course?
- rapidly progressive respiratory failure (24-48hrs)
- hypoxemia - required mechanical ventilation
- dyspnea
Prognosis is poor with 60% mortality.
Survival –> post-ARDS fibrosis leading to chronic pulmonary disease
What are the 4 most common causes that can result in ARDS?
- sepsis
- diffuse pulmonary infections/pneumonia
- gastric aspiration
- severe mechanical trauma with shock (head injuries)
Describe the pathogenesis of ARDS.
- Imbalance between proinflammatory (IL1, IL8, TNF) and anti-inflammatory (IL10, anti-proteases)
- activated macrophages release variety of cytokines that are chemotactic to neutrophils
- activated neutrophils release products that cause acute injury to alveolar capillary endothelial and epithelial lining
- Diffuse Alveolar Damage (DAD) with increased vascular permeability, loss of diffusion, necrosis of type II pneumocytes leading to surfactant loss, sloughing of surface epithelium, leadking of exudate into alveoli, hyaline membranes
What are the characteristic findings of DAD?
- increased vascular permeability
- decreased diffusion capacity
- type II pneumocyte destruction - less surfactant
- sloughing of surface epithelium
- leaking exudate into alveoli
- hyaline membranes
What is the gross morphology of ARDS?
Dark red heavy airless lungs
What is the microscopic appearance of ARDS in the acute stage? Organizing stage?
- DAD- edema, inflammation, fibrin deposition
Acute stage:
- intra-alveolar edema
- hyaline membrane formation
Organizing stage:
- proliferation of type II pneumocytes
- progressive interstitial fibrosis
What is the characteristic CXR appearance for diffuse interstitial lung disease?
Is this the definitive diagnostic standard?
Ground glass shadows
CXR is not the gold standard for diagnosis, the surgical lung biopsy is the gold standard.
However, clinical, radiologic, and histologic features are critical for accurate classification.
REgardless of etiology, end stage interstitial lung disease is always characterized by what histologic feature?
Diffuse interstitial fibrosis with or without honeycombing and cobblestone appearance.
What is the pathogenesis of diffuse interstitial lung disease?
Repeated cycles of lung injury and healing leads to widespread fibrosis and loss of lung function.
- macrophages secrete chemoattractants IL8 to activate neutrophils
- neutrophils release mediators that injure alveolar epithelial cells and connective tissue
- macrophages secrete mediators of wound healing (TGFb) that cause fibrosis
What are the 4 MAJOR categories of interstitial lung disease?
- fibrosing diseases
- smoking-related disorders
- granulomatous disorders
- eosinophilic disorders
What are the 4 major fibrosing interstitial lung diseases?
- Idiopathic pulmonary fibrosis
- Nonspecific interstitial pneumonia (NSIP)
- cryptogenic organizing pneumonia (BOOP)
- Pneumoconioses (silicosis, abestosis, pneumoconiosis)
What are the 2 smoking-related interstitial lung diseases?
- desquamative interstitial pneumonia
2. respiratory bronchiolitis
What are the 2 granulomatous disorders that cause interstitial lung disease?
- sarcoidosis
2. hypersensitivity pneumonitis
What are the clinical features of idiopathic pulmonary fibrosis?
Who is generally affected?
What is the prognosis and treatment?
Insidious onset and slow progression of dyspnea, dry cough, hypoxemia, and respiratory failure.
- older population (males>females)
- prognosis 3 years or less
- lung transplant is the only definitive therapy
What is the gross appearance of a lung that has IPF?
General appearance, cut surface, more severe areas, etc
- cobblestone appearance due to retraction of scar tissue along the interlobar septae
- cut surface shows fibrotic, compressed parenchyma
- severe in subpleural, interlobar and and lower lobes
- alternating areas of dilated air spaces and fibrotic scar bands
What is usual interstitial pneumonia? What fibrosing interstitial lung disease is it associated with?
It is the histologic pattern found in idiopathic pulmonary fibrosis, asbestosis, rheumatoid lung disease.
.
1. patchy interstitial fibrosis with temporal heterogeneity and varying intensity
2. cystic spaces (honeycomb lung)
3. variable interstitial lymphocytic infiltrates
How does the prognosis differ between Nonspecific Interstitial pneumonia (NSIP) and Idiopathic Pulmonary Fibrosis (IPF)?
NSIP is diffuse and treatable with a 90% 5 year survival.
IPF (with UIP) has a 20% survival
What is the pathology of NSIP?
temporally uniform interstitial inflammation and fibrosis
What is the clinical presentation of someone with NSIP?
45-55 years old with dyspnea and cough for several months
All other interstitial lung disorders have been ruled out.
Describe the microscopic features of cryptogenic organizing pneumonia.
What is the gold standard for diagnosis?
What is treatment?
Common response to infectious or inflammatory injury to the lungs:
** temporally uniform polyploid masses of myxoid fibroblastic tissue in peripheral airways and alveoli
Diagnosis: lung biopsy
Treatment: steroids for a long period of time
What are the 4 most common exposures that cause pneumoconioses?
- coal dust
- silica
- asbestos
- beryllium