CM- COPD Flashcards
What is obstructive lung disease?
What are the 3 main types of obstructive lung disease and what are the characteristics of each?
Disease of the lung, conducting airway or upper airway where there is a reduction in airflow during inspiration, expiration or both (usually expiration)
- COPD- emphysema (lack of elastic recoil) and chronic bronchitis (bronchospasm, inflammation, mucus, productive cough)
- Bronchiectasis- destruction of bronchi leading to collapse on exhalation
- Asthma - bronchospasm, inflammation, mucus
What are the 2 general types of COPD?
- Emphysema- loss of elastic recoil
2. Chronic Bronchitis- mucus, inflammation, bronchospasm, productive cough
What are the 3 most common symptoms of obstructive lung disease that will cause a patient to see a physician? Which diseases (emphysema, chronic bronchitis, asthma) are more likely to display certain symptoms?
- Shortness of breath - especially on exertion. All 3, but by different mechanisms
- Cough- asthma, chronic bronchitis
- Wheezing audible via stethoscope- asthma, reactive airway disease, chronic bronchitis
What is the mechanism by which asthma causes dyspnea?
Bronchospasms, inflammation and mucus production which reduce the diameter of large airways. 75% of resistance to flow occurs in expiration and is determined by cross sectional area of main bronchi and trachea.
What is the mechanism by which chronic bronchitis causes dyspnea?
Chronic inflammation causing them to be “blue bloaters”
What is the mechanism by which emphysema causes dyspnea?
- loss of lung elastic recoil- so now muscular effort is needed to drive air out
- reduction of alveolar capillary surface area resulting in lack of diffusion capacity
What can the presence, duration and timing of cough tell you about the obstructive lung disorder present?
Asthma- intermittent, more frequent at night, clear sputum. Persistent over time with clear CXR.
Chronic bronchitis- Constant for >6 months productive of clear sputum. If the color changes, it indicates a co-infection
Emphysema- not prominent component (IF they have a cough, it will be due to a co-infection)
What is wheezing suggestive of?
What obstructive lung diseases are associated with wheezing?
Why is it important to note wheezing?
It suggests bronchospasm esp. in asthma and chronic bronchitis.
This is important to note because they may respond well with bronchodilators and corticosteroids
If someone else besides the patient hears the wheezing, what does this suggest?
That it is spasm or narrowing of the upper airway and NOT COPD or asthma.
When taking history, what are the 5 most important questions to ask a patient suspected of obstructive lung disease?
- Dyspnea- when did it start? Does it get worse and better?
- Cough- sputum? intermittent or constant? is there blood? color change?
- smoking?
- allergies?
- wheezing?
What are causes of hemoptysis in sputum of someone with COPD?
Clear sputum?
Colored sputum?
Hemoptysis- PE or bronchiogenic carcinoma
Clear- asthma or chronic bronchitis
Color- co-infection in asthma, chronic bronchitis or emphysema
What is the most important determinant of the work of breathing?
Respiratory rate- RR>20 presents with symptoms of dyspnea at rest
What is the biochemical requirement of cyanosis? Patients with _______ many not manifest cyanosis while patients with _________ will demonstrate cyanosis more readily.
5g unsaturated Hb/100cc of blood.
Severely anemic patients will not manifest cyanosis but polycythemic patients will demonstrate it more easily
Which obstructive lung disease is likely to present with cyanosis? Why?
Chronic bronchitis because these patients tend to retain CO2. As pCO2 rises, pO2 must fall according to the alveolar air equation.
(asthmatics can demonstrate cyanosis ONLY in the context in the midst of a life threatening attack)
What is the alveolar air equation?
PAo2 = FiO2 x (Pb-Ph20) - PaCO2/0.8
PA02 = 0.21 x (760-47) - PaCO2/0.8
PAO2 = 150 - PaC02/0.8
What is a normal A-a gradient?
below 15 mmHg
Why are patients with chronic bronchitis “blue bloaters” and patients with emphysema “pink puffers”?
Chronic bronchitis- patient is fatter, has productive cough, and retains CO2 (RR remains normal, breaths are shallow)
Emphysema- patient is thin, tripod stance, breathing through pursed lips, and has increased RR decreasing the CO2 making PaO2 higher, making them pink
Patients with which obstructive lung disease are most likely to get decreased breath sounds? Why?
Emphysema- because they get barrel chest and the stethoscope is physically further from the conducting airways
If you hear it in asthma, it is an indication of a severe attack that constricts the airways SO MUCH, that you don’t hear wheezes or rhonchi.
In what patients are you likely to hear inspiratory wheezing? Expiratory wheezing?
Inspiratory wheezing
- asthmatics during exacerbation
- if heard w/o stethoscope- upper respiratory blockage (stridor)
Expiratory- asthma or chronic bronchitis
What are rhonchi? In what patients are they usually heard?
It is low pitch expiratory sounds heard in patients with:
- asthma
- COPD (but not usually predominant emphysema)
What should NOT be heard in patients with asthma or COPD?
What would the presence of these sounds indicate?
Rales should not be present, but if they are it suggests:
- cardiac asthma- secondary to pulmonary edema or infectious pulmonary process
- dry rales indicate restrictive disorders like pulm. fibrosis
On spirometry, the hallmark of obstructive lung disease is _____________ with ______________.
FEV1/FVC <80% predicted
What is obstruction with secondary restriction?
When the FEV1/FVC are both reduced and the FEV1/FVC ration is >70%.
When placed on a bronchodilator, what spirometry changes indicate significant improvement?
Increased FEV1 by 12% or 200mL
What is PEF?
Why is it important for prevention of symptomatic COPD/asthma?
Peak expiratory flow- this helps patients self-monitor their own spirometry with peak flow meters.
This helps “catch things early” because they can call their physician if the meter values start falling (long before symptoms)
What happens to the FVL with fixed intra or extra thoracic obstruction?
How would the patient present? What are the diff diagnoses?
The expiratory curve decreases in max flow and the volume increases in the lung.
The patient might present with wheezing/stridor
Diff diagnoses-
- larygneal carcinoma
- thyromegaly
- vocal cord asthma/dysfunction- instead of opening with inspiration, vocal cords adduct
What changes are noted on the FVL for variable extrathoracic obstruction?
What are the diff diagnoses?
The inspiratory curve is less
DD:
- obstructive sleep apnea
- tracheomalacia
What changes are noted on the FVL for variable intrathoracic obstruction?
What are the diff diagnoses?
The expiratory curve is markedly decreased with FEV1««FVC.
DD:
- asthma
- COPD
- bronchiectasis
What is DLCO?
What obstructive disorder would have a reduced DLCO?
Patients with a DLCO below ______ will develop arterial hypoxemia with exercise.
Diffusion capacity for CO.
Patients with emphysema will have a decreased DLCO because as the alveoli get destroyed so do capillaries for alveolar-arterial gas exchange (also pulmonary vascular diseases like PE)
Below 45% predicted
Who should receive blood gas measurements? Why?
Only patients with clinically impressive symptoms because the tests are invasive and uncomfortable.
- FEV1 < 30-40% and ill looking
- pCO2 of 41 in a person with severe asthma (bc it means they are developing severe respiratory acidosis
What happens to blood gases during an asthma exacerbation?
During an acute exacerbation, RR rises as does minutes and alveolar ventilation.
CO2 SHOULD decrease due to the increased RR.
In severe exacerbations, the alveolar ventilation may be normal despite the rapid RR leading to normal or elevated CO2
How does the pH, pCO2 and pO2 change from mild, to moderate, to severe asthma attacks?
pH - decreases (7.48, 7.43, 7.39)
pC02 - increases (31, 36, 41)
p02- decreases (80, 72, 60)
Describe the ABG findings in patients with emphysema,
- pCO2 will be less than 40 (low) due to the rapid shallow breaths they take.
- moderate hypoxemia- 60-70mmHg
Describe ABG findings in patients with chronic bronchitis.
- pCO2 will be >45mmHg
- pH is higher than what would be expected in the setting of respiratory acidosis because of compensatory metabolic alkalosis
- p02 <60
Who should not receive 100% oxygen? (or any amount of oxygen higher than room air (21%)?
Chronic bronchitis because they will lose hypoxic drive of respiration
What information can a CBC with differential give about obstructive lung disease?
- Anemia
- elevated Hb = chronic C02 retention and hypoxemia with compensatory erythrocytosis
- Eosinophilia= allergic or asthmatic
What would elevated bicarb suggest in a person with obstructive lung disease?
chronic C02 retention with compensatory metabolic alkalosis
