Obstructive lung disease Flashcards
two major causes of airflow obstruction
Intrinsic airway narrowing (bronchospasm, plugging, inflammation/edema) or “Floppy” airways – decreased radial tethering or decreased airway integrity
Intrinsic airway narrowing (bronchospasm, plugging, inflammation/edema) or “Floppy” airways – decreased radial tethering or decreased airway integrity
Intrinsic airway narrowing (bronchospasm, plugging, inflammation/edema) or “Floppy” airways – decreased radial tethering or decreased airway integrity
Total work of breathing = ?
work done against resistance to airflow (resistive work)vPLUS work done against the elastic recoil of the respiratory system (elastic work).
How do obstructive diseases affect airflow and lung volumes and diaphragm
Airflow is decreased and lung volumes increase (due to incomplete emptying of alveoli causing air trapping). Diaphragm is flattened to allow hyperventilation which then reduces inspiratory pressure and inspiratory capacity
What location of airway does bronchitis, asthma, bronchiectasis, bronchiolitis and emphysema affect?
Bronchitis: Bronchi. Asthma and bronchiectasis: bronchi/bronchioles. Bronchiolitis: respiratory bronchioles. Emphysema: alveolar sacs
Asthma definition
Asthma is a chronic, reversible inflammatory disorder of the airways associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness, and coughing particularly at night or in the early morning
Two types of asthma
Extrinsic (type I hypersensitivity rxn to outside agent) and intrinsic (non immune rxn to aspirin, infection, stress, exercise).
Subtypes of extrinsic asthma
atopic or allergic asthma, occupational asthma, and allergic bronchopulmonary aspergillosis.
Factors that influence asthma development
–genetic predisposition to atopy or airway hyper responsiveness, obesity, and sex. Exposure to allergens, infection, occupational exposures, smoke, pollution, diet
Describe airway inflammation in asthma and cells involved
airway inflammation in asthma is persistent even though symptoms may be intermittent. Involves mast cells (histamine, prostaglandin), Eosinophils, Th2 (cytokine release), dendritic cells, macrophage, neutrophils
Structural changes in asthma
Increase in airway smooth muscle cells due to hypertrophy and hyperplasia, Blood vessel proliferation, Mucus hyper-secretion in the context of increased number of goblet cells and increase size of submucosal glands.
Key clinical features of asthma
Intermittent (PFTs can be normal btw), reversibility of obstruction, cough, dyspnea, wheezing, exacerbations to exercise, cold air, allergens, nl to increased DLCO
Test used to detect asthma
Bronchoprovocation with methacholine (or exercise alone) will show decreased FEV at lower conc than healthy people. The PC20 is the concentration required to lower airflow FEV by 20%
Signs of acute asthma
hyperinflation, decreased tension and pressure from diaphragm, Breathing at flatter part of P-V curve so more pressure required to get similar change in volume, accessory muscles, increased work of breathing
Asthma severity levels
intermittent (2X/ week), moderate persistent (daily symptoms, multiple exacerbations per week), severe persistent (continual symptoms, frequent exacerbations)
Vocal cord dysfunction
•Inappropriate vocal cord adduction during inspiration results in airflow obstruction. Symptoms mimic asthma
Stridor
Wheezing sound upon inhalation (seen in vocal cord dysfunction)
Vocal cord dysfunction bronchoprovocation
FEV and the 20% change concentration will not change in VCD, but VCD may worsen
COPD definition
fixed airflow limitation- includes emphysema and chronic bronchitis
Chronic bronchitis defn
•Productive cough at least 3 months over the past 2 years without other cause. Increased airway resistance due to changes in airway structure (edema, mucus, fibrosis). May have overlapping features with asthma. Impaired ventilation
chronic bronchitis airways
hypertrophied submucosal glands and increased in number, with increased ratio of glands to bronchial wall thickness. Goblet cells increased in number. Airway lumen is narrowed
P-V curve in chronic bronchitis
shifted upwards
Chronic bronchitis is a disease of ________________ while emphysema is a disease of _____________________
airways, parenchymal disease (loss of tissue elastic recoil)
Emphysema pathogenesis
Loss of normal alveolar spaces with enlargement of distal airspaces. Increased lung compliance (lung is less stiff due to decreased elastic tissue, alpha-1-antitrypsin deficit, apoptosis of alveolar cells, impaired repair). Impaired gas exchange
types of distal airspace enlargement in emphysema
pan-acinar involves entire distal airspace (acinus), seen in older patients and alpha1 antitrypsin deficiency. Centri-acinar involves respiratory bronchioles and is smoking related
