Pathology of Obstructive Lung Diseases Flashcards
What is the major pathological feature of asthma?
Airway inflammation and bronchoconstriction due to an exaggerated immune response to triggers, leading to narrowing of the airways.
What are the key complications associated with asthma?
Acute exacerbations, airway remodeling, persistent airflow limitation, and hypoxemia during severe attacks.
Complication: Hypoxic cor pulmonale can occur in severe, uncontrolled asthma.
What is the major pathological feature of chronic bronchitis?
Chronic inflammation of the bronchi with mucus hypersecretion, leading to productive cough and airflow obstruction.
What are the key complications of chronic bronchitis?
Recurrent respiratory infections, hypoxemia, cor pulmonale (right-sided heart failure due to lung disease), and respiratory failure.
What is the major pathological feature of emphysema?
Destruction of alveolar walls and loss of elastic recoil, leading to air trapping and hyperinflation of the lungs.
What are the key complications of emphysema?
Progressive dyspnea, hypoxemia, pulmonary hypertension, and cor pulmonale. In severe cases, respiratory failure and pneumothorax can occur.
What is hypoxic cor pulmonale?
Right-sided heart failure caused by prolonged hypoxia in lung diseases like asthma, chronic bronchitis, and emphysema. It occurs due to increased pulmonary vascular resistance from chronic lung disease, leading to strain on the right side of the heart.
How does chronic bronchitis differ from emphysema in terms of pathology?
Chronic bronchitis involves mucus hypersecretion and airway inflammation, whereas emphysema involves destruction of alveolar walls and loss of lung elasticity.
What are the common symptoms of asthma?
Symptoms include wheezing, shortness of breath (dyspnea), chest tightness, and coughing, especially at night or early in the morning.
How does asthma typically affect the clinical pattern of symptoms?
Asthma symptoms are often intermittent and reversible, triggered by factors such as allergens, exercise, cold air, or respiratory infections. Symptoms tend to worsen at night or early in the morning due to changes in airway tone and inflammation.
How does airway obstruction in asthma affect oxygenation (O2)?
In asthma, bronchoconstriction and airway inflammation lead to airway narrowing, which impairs airflow and reduces the ability of oxygen to reach the alveoli. This results in decreased oxygenation of the blood (hypoxemia).
What is the impact of air trapping in asthma on O2 levels?
Air trapping due to bronchoconstriction and inflammation leads to increased residual volume and hyperinflation of the lungs. This can reduce ventilation and impair the exchange of gases, including oxygen, causing hypoxemia (low blood oxygen levels).
How does severe asthma exacerbation affect the O2 alveolar gas?
During a severe asthma exacerbation, severe airway obstruction leads to ventilation-perfusion mismatch, where areas of the lung are well-perfused but poorly ventilated. This results in hypoxemia due to reduced oxygen diffusion across the alveolar-capillary membrane.
How can blood gas analysis in asthma show evidence of hypoxemia?
In severe asthma exacerbations, arterial blood gas (ABG) analysis may show low oxygen levels (hypoxemia) and normal or slightly low CO2 levels early in the attack. As the attack progresses, CO2 levels may rise, indicating respiratory fatigue or failure.
What is the relationship between bronchoconstriction and O2 delivery in asthma?
Bronchoconstriction decreases airflow to the alveoli, reducing the amount of oxygen available for gas exchange. This leads to lower oxygen levels in the alveoli and subsequently in the blood, contributing to hypoxemia and increased work of breathing.
What is the term ‘shunt’ in the context of pulmonary physiology?
A shunt refers to the diversion of blood from the pulmonary circulation to the systemic circulation without being oxygenated in the lungs. This occurs when blood passes through areas of the lung that are poorly ventilated or not ventilated at all (e.g., due to pneumonia, atelectasis, or severe asthma), resulting in hypoxemia because oxygen cannot be exchanged in these areas.
FURTHER INFO:
A shunt refers to the diversion of blood from the pulmonary circulation to the systemic circulation without being oxygenated in the lungs. This occurs when blood passes through areas of the lung that are poorly ventilated or not ventilated at all (e.g., due to pneumonia, atelectasis, or severe asthma), resulting in hypoxemia because oxygen cannot be exchanged in these areas.
What is anatomical dead space?
Anatomical dead space refers to the parts of the respiratory system (like the trachea and bronchi) where gas exchange does not occur. It is the volume of air that fills the conducting airways and does not participate in oxygen-carbon dioxide exchange.
What is alveolar dead space?
Alveolar dead space refers to the alveoli where gas exchange should occur, but it is impaired or absent due to factors like poor blood flow or alveolar damage. This space is ventilated but not perfused, so the air doesn’t participate in gas exchange.
What is physiologic dead space?
Physiologic dead space is the total volume of the respiratory system where gas exchange does not occur, combining both anatomical dead space (conducting airways) and alveolar dead space (poorly perfused alveoli). It represents the ineffective ventilation in the lungs.
How does physiologic dead space differ from anatomical dead space?
Physiologic dead space includes both anatomical dead space and alveolar dead space. While anatomical dead space only accounts for the airways that do not participate in gas exchange, physiologic dead space accounts for both the non-functional airways and any alveoli that fail to exchange gases due to perfusion problems.
What conditions can cause an increase in alveolar dead space?
Conditions such as pulmonary embolism, COPD, or acute respiratory distress syndrome (ARDS) can cause an increase in alveolar dead space by impairing blood flow to certain parts of the lungs, leading to poorly perfused or non-functional alveoli.
How does increased physiologic dead space affect gas exchange?
Increased physiologic dead space leads to less effective ventilation since a larger proportion of the inspired air is not participating in gas exchange. This can result in hypoxemia (low oxygen levels) and hypercapnia (high carbon dioxide levels), especially in conditions where ventilation exceeds perfusion.
