Session 8: COPD Flashcards
What is COPD?
Airflow disease (obstructive) caused by two conditions. Usually progressive and associated with an abnormal inflammatory response to noxious particles and gases.
COPD is an umbrella term for two conditions, which?
Chronic bronchitis Emphysema
Aetiology of COPD
90% due to tobacco smoking. <10% due to alpha1-antitrypsin deficiency.
When does COPD most commonly present?
In older patients which have smoked more or less their entire lives.
Explain how alpha1-antitrypsin deficiency leads to COPD.
Alpha1-antitrypsin is an antiprotease. In this condition there is an imbalance between proteases and antiproteases in the lung. This leads to destruction of the alveolar walls and elastin leading to emphysema.
When does alpha1-antitrypsin-associated COPD most commonly occur?
In young ages as it is inherited.
Broad pathophysiology of COPD.
Exposure to tobacco smoking and other noxious particles leads to a chronic inflammatory response. This leads to oxidative injury which damages the parenchyma of the lungs, the peripheral airways, the vasculature as well as the alveoli.
Two broad pathological changes occur in COPD, which?
Increased production of mucus and reduced clearance of mucus and associated pathogens. Respiratory defects + vasculature.
Explain the cause of disrupted clearance of mucus and pathogens in COPD.
Enlargement of the mucus-secreting glands in the airways. Metaplasia of ciliated respiratory epithelium to normal columnar with increased expression of goblet cells. This also leads to ciliary destruction and dysfunction.
Explain the respiratory defects and vasculature changes of COPD.
Breakdown of elastin leads to reduced elastic recoil. Also causes narrowing of bronchioles due to loss of radial traction. Also causes alveoli to collapse and form larger alveoli (formation of bullae). This leads to reduced surface area and reduced exchange. The vascular bed changes causes hypoxia, vasoconstriction and pulmonary hypertension.
What is emphysema caused by?
Breakdown of elastin.
Consequences of chronic bronchitis.
Increased mucus production and reduced clearance.
Is COPD reversible?
No
COPD leads to airway resistance. What causes it (think 3 changes)?
1 - Luminal obstruction because of increased mucus secretions and reduced clearance. 2 - narrowing of small bronchioles as radial traction is lost (outward pull) by elastin of surrounding alveoli. 3 - Elastin loss leads to reduced elastic recoil -> reduced expiratory force.
What is the consequence of reduced expiratory force?
Hyperinflation
State a cardiac consequence of COPD
Right heart failure (cor pulmonale)
Explain how cor pulmonale can occur in COPD.
Hypoxia due to the obstructive nature of the disease. This leads to vasoconstriction of the pulmonary vessels. This vasoconstriction leads to pulmonary hypertension. This can lead to RV hypertrophy and subsequent R heart failure.
What is the common history of a patient with COPD?
Older with a long history of smoking.
What is the most common initial symptom of COPD?
Coughing
Describe the initial cough associated with COPD.
Usually a morning cough that becomes more constant as the disease progresses. It is usually a productive cough meaning it produces sputum.
The sputum of the cough in COPD may change. Due to what?
Exarcerbations or superimposed infections related to COPD.
Give an example of another common initial symptoms of COPD.
Shortness of breath that may get worse upon exertion. This can progress to shortness of breath even on rest as the disease gets worse.
Upon physical examination of a patient with COPD, what might you find? (Early to middle stages)
Tachypnoea Use of accessory muscles to aid the patients breathing Barrel chest Hyper-resonance upon percussion. Reduced intensity breath sounds Reduced air entry Wheezing (not as common)
