Obstructive Lung Disease Flashcards
Asthma general characteristics
- chronic inflammatory disorder
- associated w/airway hyperresponsiveness ==>
- recurrent episodes of wheezing, breathlessness, chest tightness, and coughing
- reversible spontaneously or w/treatment
Airway inflammation in Asthma
- persistant inflammation ==> most prominent @ medium-sized bronchi
- inflammatory cells involved =
- mast cells
- eosinophils
- T lymphocytes
- dendritic cells
- neutrophils
Structural airway changes in asthma
- increased smooth muscle cells
- blood vessel proliferation
- mucus hyper-secretion (increased goblet cells + submucosal glands)
Control of Airway diameter
- neural regulation
- parasympathetic (cholinergic) motor neurons via vagus ==> aCH stimulates smooth muscle contraction
- nonadrenergic noncholinergic receptors (excitatory and inhibitory)
- Beta-adrenergic ==> increase intracell cAMP ==> smooth muscle relax
- ion channels: Ca2+ and K+
Physiologic consequences of asthmatic airflow obstruction
- increased resistance to airflow (accentuated during expiration) ==> air trapping ==> hyperinflation
- hyperinflation ==> flattening of diaphragm ==> inefficient msucular respiratory effort
Mechanics of diaphragm in obstructive lung disease
- Muscle fibers of the flattened (shortened) diaphragm cannot generate adequate tension ==> operating @ suboptimal point on length-tension curve
- in addition to overcoming increased airway resistance, the asthmatic must use less efficient respiratory muscles to inflate their lungs.
- these pathophysiologic effects increase oxygen consumption and carbon dioxide production by the diaphragm (and other respiratory muscles).
PFTs in Asthma
- exacerbation ==> obstructive pattern
- DECREASE in FEV1/FVC that usually responds to beta-adrenergic agent
- improvement = >12% or >200mL
- increase in TLC, RV and FRC due to air trapping
- DECREASE in FEV1/FVC that usually responds to beta-adrenergic agent
- may look normal in between episodes
Bronchoprovocation testing in possible asthmatics
- serial spirometry after inhaling progressively high concentrations of methacholine (histamine analog)
- PC20 = concentration required to lower FEV1
- several times lower in asthmatics than healthy people
- Can also be performed using exercise as bronchoprovocation

Goals of asthma therapy & strategies
- reduce airway tone
- beta-agonists (albuterol)
- anti-cholinergers
- leukotriene inhibitors
- methylxanthines = PDE inhibitor ==> increase intracell cAMP
- reduce inflammation
- corticosteroids
- mast cell stabilizers
- leukotriene inhibitors
- Anti-IgE therapy
Acute asthma treatment
- systemic corticosteroids
- inhaled bronchodilators (beta-agonists, anticholinergics)
- possibly: positive pressure ventilation or mechanical vent
Asthma severity classification system

COPD general characteristics
- irreversible airflow limitation
- FEV1/FVC < .7
- risk factors:
- smoking
- inhaled biomass smoke
- occupational exposures
- subtypes:
- emphysema
- bronchitis
- chronic obstructive asthma

Characteristics of Chronic Bronchitis
- Clinical: productive cough for 3 months per year over 2 year period w/out other explanation
- airway epithelium ==> squamous metaplasia
- disease of airways (vs. emphysema = disease of parenchyma)
- increased airway resistance due to changes in airway structure ==> impaired ventilation
- normal DLCO
- minimal reversibility
Characteristics of Emphysema
- enlargement of air spaces distal to terminal bronchioles accompanies by destruction of their walls
- airflow obstruction due to airway collapse during expiration
- most common cause = smoking
- may also be cause by alpha1 anti-trypsin deficiency
Pathophysiology of chronic bronchitis
- limitation of airflow (particularly expiratory)
- resistance due to excessive mucous secretion + bronchial wall inflammation/thickening
Pathophysiology of ephysema
- limitation in airflow rates (expiratory)
- loss of alveolar-capillary surface area + loss of elastic recoil
PFTs for COPD
- FEV1/FVC < /7
- RV, FRC, and TLC are all increased
- Chronic bronchitis = normal DLCO
- Emphysema = low DLCO
Clinical presentation of COPD
- dyspnea
- cough, wheezing, chronic sputum production
- evidence of hyperinflation
- limited diaphragm movement + use of accessory muscles
- purse-lipped breathing
- tripodding
- breath/heart sounds diminished
- prolonged forced expiratory time
Severity of COPD
- GOLD classification. Survival is associated with the FEV1 as well. The lower the FEV1, the poorer the survival.
- Other contributors: severity of symptoms, risk of exacerbations and comorbid conditions.
- Zero to one exacerbation per year is considered low risk for exacerbations, while >= 2 per year is considered high risk for future exacerbations.

COPD treatment
- releave sx and reduce severity of exacerbations
- agents to relax airway: inhaled anticholinergics, beta-agonists
- agents to decrease inflammation/edema: corticosteroids
- smoking cessation
- respiratory rehab, O2 therapy, lung transplant
Bronchiectasis characteristics
- abnormal dilation of proximal medium-sized bronchi (cartilage-containing airways)
- destruction of muscular and elastic components of airway walls
- common associated conditions:
- chronic bacterial infection ==> large quantities of foul-smelling sputum
- leads to impaire tracheobroncial clearance ==> predisposes to airway colonization and infection
Common causes of bronchiectasis
- severe pulmonary infection
- bronchial obstruction
- primary ciliary dyskinesia
- immunodeficiency
- cystic fibrosis
Cystic Fibrosis characteristics
- CFTR mutation ==> dysfxnl chloride transport
- recurrent sinus/pulmonary infections
- PMN recruitment ==> widespread airway inflammation/decstruction ==> bronchiectasis
- respiratory sx, GI sx, failure to thrive
- pancreatitis, diabetes, male infertility
- dx via sweat test
Cystic Fibrosis Tx
- CFTR modulators
- antibiotics
- bronhcodilators
- nebulized hypertonic saline
- inhaled DNAase I
- Chest physiotherpay
- exercise
- lung transplant
Bronchiolitis characteristics
- inflammation of the membranous bronchioles
- children = usually viral illness ==> fever, cough, dyspnea
- adults = toxic gases, immune-mediated, drugs, transplant reject
- auscultatory hallmark: inspiratory squeak
Upper airway obstruction characteristics
- patterns of obstruction: variable extrathoracic obstruction, variable intrathoracic obstruction, and fixed obstruction
