What are the 2 major causes of airflow obstruction?
1. Intrinsic airway narrowing (bronchospasm, plugging, inflammation/edema) 2. Floppy airways (decreased radial tethering or decreased airway integrity)
The work of breathing is mainly comprised of the work against what 2 forces?
1. resistive forces 2. elastic forces
With hyperinflation, which lung volume(s) are increased?
Functional residual capacity is increased, residual volume is increased, expiratory reserve volume is increased. FRC = ERV + RV
What is asthma?
Asthma is a chronic inflammatory disorder of the airways.
Asthma leads to airway ____ responsiveness
What are common symptoms of asthma? (name 4)
1. recurrent episodes of wheezing
3. chest tightness
4. coughing, particularly at night or in the early morning
Asthma episodes are associated with airflow _______
What is extrinsic asthma?
Extrinsic asthma is allergic asthma. It is in response to environmental antigens (allergic, occupational, etc). It is mainly IgE mediated
What is intrinsic asthma?
Intrinsic asthma is the nonseasonal, non allergic form of asthma. It tends to be chronic and persistent. It can be post-viral where epithelial injury leads to bronchial narrowing, or it could be due to altered arachidonic acid metabolites (increased leukotrienes, decreased prostaglandings - these patients may have worsening of their asthma if they take aspirin or ibuprofen)
What causes development of asthma?
The causes of asthma aren't really known but it is thought to be multifactorial.
-exposure to allergens
-tobacco smoke, air pollution
What is the final common pathway to symptoms and physiologic change in asthma?
Airway narrowing. Roughly understand the chart below
Asthma is intermittent. What does this mean?
PFTs are completely normal between exacerbations
True or False: there is reversibility of airflow obstruction in asthma
What 5 things can exacerbate asthma?
2. cold air
4. air pollution
What happens to DLCO in asthma patients?
DLCO is normal or increased
How can you tell the difference between asthma and vocal cord dysfunction?
Asthma presents with expiratory wheezing while vocal cord dysfunction presents with inspiratory stridor.
How can bronchoprovocation detect occult asthma (or exclude the diagnosis)?
You give methacholine from a low dose to see if they have a drop in FEV1 (at least 20 percent change) before hitting 8 mg/ml.
What happens with acute asthma?
2. Decrease in tension and pressure generated by shortened and flattened diaphragm muscle
3. Breathing occurs on the flatter part of the PV curve, more pressure is required to get a small change in volume
4. accessory muscle use
5. increased work for breathing
What does the P-V curve look like for acute asthma?
What are the classes of asthma severity and what symptoms go along with each?
What is vocal cord dysfunction?
Inappropriate vocal cord motion results in airflow obstruction
What does the volume-flow loop look like for vocal cord dysfunction?
It has the extrathoracic obstructive pattern due to adduction of vocal cords during inspiration
True or False: Stridor from vocal cords is often mistaken for wheezing from asthma
How do you diagnose vocal cord dysfunction?
Fiberoptic laryngoscopy can visualize the vocal cords during breathing
How does vocal cord dysfunction respond to bronchoprovocation?
Bronchoprovocation may worsen the sound of VCD but it will not change the FEV1 or PC20. This can help you distinguish between VCD and asthma
What is COPD?
Chronic obstructive pulmonary disease. It is defined by fixed airflow limitation with an FEV1/FVC less than 70%.
True or False: Tobacco smoke exposure is a minor risk factor for COPD.
False! It's a major risk factor
COPD is broken down into 2 major catagories. What are they?
1. Bronchitis (inflammation and mucus in the airway)
2. Emphysema (floppy airways and destruction of alveolar units)
After 50 years of smoking, what % of people will have COPD?
20%. While smoking is a major risk factor, there are other things involved.
What is chronic bronchitis?
It is a productive cough that lasts at least 3 months over the past 2 years without any identifiable cause. There is increased airway resistance due to changes in airway structure (edema, mucus, fibrosis) and may have overlapping features with asthma. Chronic bronchitis impairs ventilation.
What are the mucus glands like in chronic bronchitis?
In chronic bronchitis, the mucus glands are thicker and there are more of them.
What is the P-V curve like in chronic bronchitis?
What happens at the level of the alveoli in emphysema?
There is a loss of normal alveolar spaces with enlargement of distal airspaces
Emphysema results in _____ compliance of the lung
In emphysema, what 4 things cause the increase of compliance of the lung?
1. decreased elastic tissue
2. imbalance between proteases and anti-proteases in the lung (alpha-1-antitrypsin deficiency)
3. increased apoptosis of alveolar cells
4. impaired repair mechanisms
Emphysema causes ____ gas exchange
Impaired gas exchange
What is the difference between pan-acinar and centri-acinar emphysema?
Pan-acinar emphysema involves the entire acinus. It is caused by alpha-1-anti-trypsin deficiency.
Centri-acinar emphysema is typicallly smoking related and involves alveoli in the respiratory bronchioles but not the distal alveoli.
In emphysema, airflow obstruction happens due to dynamic airway collapse. This is due to decreased ___ _____.
Decreased radial traction. The decreased radial traction causes a loss of elasticity surrounding the tissue which causes the airways to be floppy and collapse easily.
What is the P-V curve like for emphysema?
What are 3 physical exam findings for chronic bronchitis?
1. Cough (productive cough)
2. Rhonchi (low rumbling sound)
3. Wheezing (on expiration)
What are 2 physical exam findings for emphysema?
1. Diminished breath sounds (not much air movement due to tissue distruction)
2. Hyper-resonant (percussion), due to hyperventilation
What are 3 physical exam findings that are common between chronic bronchitis and emphysema?
1. Prolonged expiratory phase
2. Pursed-lip breathing
3. Tri-pod breathing
How is COPD classified?
Note that all stages of COPD have to have a FEV1/FVC ratio less than 70% but the severity of COPD differs in the % predicted FEV1.
What are 3 physical exam findings for acute exacerbation of COPD?
1. Increased cough
2. Increased sputum volume and purulence
3. Increased wheezing
How does acute exacerbation of COPD appear on CXR?
What is shown on PFTs when there is an acute exacerbation of COPD?
What can cause acute exacerbation of COPD? (4)
4. Other unknown factors
How is acute exacerbation of COPD treated? (3)
What are the causes of death from COPD? (5)
1. Respiratory failure
2. Right ventricular failure
4. Spontaneous pneumothorax
5. Pulmonary embolism
What happens to DLCO in asthma, chronic bronchitis, and emphysema?
In asthma and chronic bronchitis, DLCO is either normal or slightly in creased.
With emphysema, DLCO is decreased.