11 - Chronic Obstructive Pulmonary Disease Flashcards
COPD is mostly caused by ___ and ___.
Emphysema and chronic bronchitis
Patients with asthma can be considered to have COPD if they have ___.
airway remodeling (leads to irreversible obstruction)
What is the definition of emphysema?
- abnormal permanent distal airspace enlargement (in respiratory bronchioles)
- destructive changes of alveolar wall without obvious fibrosis
- can be distal acinar, pan acinar, paraseptal, or subpleural
What is the definition of chronic bronchitis?
- Cough and sputum most days for a minimum of 3 months for 2 consecutive years
- airflow obstruction may not be present
- excess mucus secretion
What are the risk factors for COPD?
Exposures
- tobacco smoke
- environmental tobacco smoke
- occupational dust and chemicals
- indoor/outdoor pollution
- infection
Host factors
- bronchial hyperreflexiveness (BHR)
- bronchopulmonary dysplasia (BPD)
- genetic
- maternal smoking
- childhood asthma
- HIV
- tuberculosis
- decreased socioeconomic status
What are the three mechanisms of disease in COPD?
- chronic inflammation (lymphocytes, alveolar macrophages, neutrophils)
- elastase/anti-elastase imbalance
- oxidative stress
What causes COPD to continue to progress after the precipitating factor is no longer present?
- immune dysregulation/autoimmunity
- alveolar epithelial cell senescence
In which lung disease is hyperinflation most common? Why?
Emphysema
Not as likely in other lung diseases because they are usually not associated with decreased elastic recoil or decreased radial traction
What are the pathophysiologic explanations for signs and symptoms of COPD?
- increased WOB, increased dead space, decreased respiratory muscle function, hypoxemia –> dyspnea and tachypnea
- airflow obstruction –> wheeze, increased expiratory time
- mucus gland and airway receptor stimulation –> cough and sputum
- decreased food intake and systemic inflammation –> weight loss and peripheral weakness
- hyperinflation and diaphragm dysfunction –> thoracoabdominal paradox, Hoover sign, accessorry muscle use
- increased pulmonary vascular resistance –> pulmonary hypertension, cor pulmonale
What PFT pattern is consistent with COPD?
- decreased FEV1
- decreased or normal FVC
- decreased FEV1/FVC
- increased TLC
- decreased DLCO (if emphysema is present)
- decreased MIP (if significant hyperinflation)
What causes hypoxemia in COPD?
V/Q mismatch
What causes hypercapnia in COPD?
- increased dead space
- decreased diaphragmatic capacity
- abnormal control of breathing
- smaller tidal volumes (leading to increased dead space fraction)
Why might COPD patients breathe rapidly and shallowly?
Hyperinflation and increased elastic work of breathing –> fast, shallow breathing minimizes work on each breath
At what PaO2 do you give supplemental oxygen to someone with COPD?
PaO2 ≤ 55 mmHg OR PaO2 ≤ 60 mmHg if there is also pulmonary hypertension
What are the treatments for COPD?
- smoking cessation
- supplemental oxygen (in some cases)
- short acting bronchodilators as needed
- long acting bronchodilators and inhaled corticosteroids
- pulmonary rehab
What is the definition of COPD?
- persistent respiratory symptoms and airflow limitation due to airway and/or alveolar abnormalities
- mixture of small airway disease and parenchymal destruction
What are the known alpha-1 antitrypsin mutations? Which is the most common? Most severe?
- PiZZ (most common and most severe)
- PiSZ
- PiMZ
- PiSS
- PiMM
What does emphysema at an early age suggest?
Alpha-1 antitrypsin deficiency
What part of the lungs does alpha-1 antitrypsin deficiency affect? What part of the lobe?
Lower lobes, panlobular/panacinar
What is the proper treatment for someone with alpha-1 antitrypsin deficiency-induced emphysema
- stop smoking, if applicable
- replacement therapy
- treat infections
What small airway changes are seen in COPD?
- thickening of airway wall
- goblet cells
- lymphoid follicles
- loss of elasticity and disrupted alveolar attachments (airway-parenchymal interdependence)
- lumen occlusion by mucus and inflammatory exudate
- fibrosis
What mechanisms in emphysema cause expiratory flow limitation? What mechanisms in chronic bronchitis cause expiratory flow limitation?
Emphysema:
- loss of radial traction
- loss of elastic recoil
Chronic bronchitis
- increased airway resistance (from edema, smooth muscle, mucus, and inflammation)
How does hyperinflation affect work of breathing?
It increases it because there is reduced compliance
At what PaO2 and SpO2 levels do you give someone with COPD supplemental oxygen?
PaO2 ≥ 55 mmHg or SpO2 ≥ 88%
