Pathophysiology and Treatment of COPD - Kradjan Flashcards
What are the two guidelines for COPD?
Global Initiative for Chronic Obstructive Lung Disease
American Thoracic Society (ATS) and European Respiratory Society (ERS) joint guidelines
The guidelines are very similar
“A common preventable and treatable disease characterized by AIRFLOW limitation that is usually PROGRESSIVE and associated with an inflammatory response in the airways and lungs to noxious particles. Is not fully reversible”
COPD
What are the two major conditions associated with COPD?
Chronic bronchitis and emphysema. Asthma may be present, but is not included in COPD.
What is the airflow limitation in COPD caused by?
- Small airways disease and fibrosis
- Destruction of lung parenchyma (emphysema)
These seem to be caused by inflammation (systemic and pulmonary) that is a amplification of normal inflammatory response to noxious particles.
What percentage of people have COPD over 55?
2-10%. 4th leading cause of death after CAD (coronary artery disease), cancer, and stroke.
What is the concerning observation of a graph of the leading causes of death over the last 50 years?
The other causes of death seem to be in a downward trend, while COPD is on an upward trend (at least until 1998 when the graph stops)
Term: Presence of chronic productive cough for three months in each of two consecutive years in a patient in whom other causes of chronic cough (eg heart failure) have been excluded.
Chronic bronchitis
Looking at a small airway, how would it differ in chronic bronchitis vs. asthma?
In asthma the small airways would be constricted to just a portion of their normal size. In chronic bronchitis, there is fluid in the airways.
On a chest x-ray, how would emphysema present?
It would present as balloon shaped bullae. This impairs the gas exchange.
How does a patient with chronic bronchitis present usually?
Early: smoker’s cough, mucous production. Little functional problems early on (little SOB, exercise intolerance or change in PFT’s). (10-15 years of irritating but functional symptoms.
Moderate: SOB and exercise intolerance start to interfere with activities of normal living.
Moderate to severe: From here PFT’s decline. End stage is less than 50% of normal CO2 retention. Rales, bronchi, SOB with few steps. Recurrent infections.
What does emphysema do to the body?
- Destruction of alveolar walls, but without obvious fibrosis
- Abnormal permanent enlargement of the terminal airspaces (decreased air exchange location, less gas exchange).
- Air trapping (dead space)
- Loss of elastic recoil and structural support
- Obstruction and airway collapse during expiration
- Balloon shaped bullae on CXR
What is the pink puffer?
Sufferer of emphysema
How do you recognize a pink puffer?
- pursed lip breathing
- barrel chest
- less CO2 retention and hypoxia by breathing harder
- no mucus production
- bullae rupture, pneumothorax
- shortness of breath and decreased exercise capacity
What is the number one risk factor for COPD?
Smoking. 80-90% of cases linked to smoking.
50% of smokers have symptoms
What rate of decline in FEV1 is normal for non-smokers compared to smokers?
non-smokers: 25 mL/year
smokers: 50 mL/year
If you stop smoking, what happens to your FEV?
It doesn’t return to a non-smoker status, but it doesn’t decline as quickly.
What part do enzymes play in COPD?
The natural enzymes enhance lung tissue destruction.
- Elastases, proteases, cysteine proteinase, trypsin, matrix metaaloproteinases
What enzymes play a role in protecting the lungs?
elastase inhibitors, anti-proteases
How do people with a deficiency in alpha-1-antitrypsin present (an anti-protease)?
They do not have the mechanism to inhibit proteases, and so they develop emphysema symptoms by age 20 w/o smoking.
What is the mechanism for smoking?
Neutrophils and macrophages are attracted, and inhibitors are inactivated. Elastase is released.
How do COPD and asthma relate to each other?
They both have a chronic airway obstruction
Acute and chronic inflammation
Overproduction of some mucus glands (chronic bronchitis only)
Smooth muscle hypertrophy
How do asthma and COPD differ?
COPD
Lower airway disease
Greater role of neutrophils over eosinophils
IL-8 and type I helper CD8 T lymphocytes (instead of IL-5)
Oxidative stress
Fixed airway obstruction without reversibility (or limited at least)
Tissue destruction
What are the inflammatory mediators in asthma? COPD?
Eosinophils for asthma, neutrophils for COPD.
When is the usual age of onset in COPD?
40’s or later.