Obstructive Lung Diseases Flashcards
Where are 3 areas where obstruction leading to increased resistance can occur?
- Inside the lumen
- in the airway wall
- Surrounding the airway
What is happening with restrictive diseases?
Expansion of the lung is restricted
What 4 things can cause expansion of the lung to be restricted?
- Alterations in the parenchyma
- Diseases of the pleura
- Diseases of the chest wall
- Diseases of the neuromuscular apparatus
What are 4 symptoms/physiological processes contributing to asthma?
- Widespread narrowing of the airways (bronchoconstriction)
- hyper-responsiveness of the smooth muscle to contract - Excessive mucous secretion
- Chronic inflammation
- Chest tightening, wheezing, and cough
What is the definition of airway hyper-responsiveness?
the capacity of the airways to undergo exaggerated narrowing in response to stimuli that do not result in a comparable degree of airway narrowing in healthy subjects
What is the methacholine test?
Methacholine given to patient via nebulised spray, and causes bronchoconstriction via muscarinic receptors. Degree of narrowing quantified by spirometry. Asthmatics will react to much lower doses.
Following the methocholine test, what is given to asses reversibility?
Bronchodilator is administered
Why is there thought to be extensive remodelling of airway tissue in asthmatic patients?
ongoing tissue injury caused by infectious agents, allergens, or inhaled particultes
What drives the persistence of asthma?
Ongoing host immune responses that generate mediators responsible for remodelling
Lungs are usually hyperinflated in asthma patients as a consequence of…?
extensive mucous plugging
the causes of asthma then are…
- extensive contractile response of smooth muscle = bronchoconstricion + airflow obstruction
- Extensive remodelling
What are 5 treatments for asthma?
- short acting ß antagonists to counteract bronchoconstriction
- corticosteroids to control inflammation
- Leukotriene antagonists
- Long acting muscarinic antagonists
- Anti IgG monoclonal antibody and bronchial thermoplasty
- very expensive
What is the 4th leading cause of death worldwide?
COPD
What is the definition of COPD?
progressive loss of lung function with airflow obstruction that is not full reversible with bronchodilators
What is emphysema?
presence of permanent enlargement of the airspaces distal to the terminal bronchioles and destruction of their walls
- destroys gas exchange surfaces
What are the two forms of emphysema?
- centriacinar
2. panacinar
What is centriacinar emphysema?
he destruction is limited to the central part of the lobule and the peripheral
ducts and alveoli may be fine
What is panacinar emphysema?
distension and destruction of entire lobule. Throughout lung, but more common towards bottom
more severe
What is the role of Alpha-1 antitrypsin in emphysema?
inhibitor of serine proteases, including neutrophil elastase
genetic disease can cause it to accumulate in ER of liver and not make it to lung
- N.E. can then destroy connective tissue matrix of lung
People are at greater risk (especially if they smoke) of developing COPD
Can also develop paracinar emphysema early on
What is different between the effects of the alpha-1 antitrypsin deficiency on the liver vs. lungs?
liver disease: loss of function mechanism
lung disease: gain of function mechanism
What are 2 (and a potential third) risk factors for developing emphysema?
- Smoking (50%)
- Pollution
- potentially agricultural pesticides
What is the pathogenesis of emphysema?
- induction of pro-inflammatory signalling pathways results in recruitment of neutrophils and macrophages
- Inflammatory cells arrive at site and make more cytokines and oxidants
- Destruction of elastic matrix of alveoli from NE (cleaves type IV collagen)
What is the definition of chronic bronchitis?
chronic productive cough for 3 months in each of 2 successive years
Most patients with COPD show symptoms of emphysema and bronchitis but which is more common?
chronic bronchitis