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Flashcards in 23 Chronic Obstructive Pulmonary Disease Deck (21)
1

Chronic obstructive pulmonary disease (COPD):
Global initiative for obstructive lung disease (GOLD) definition

  • A common preventable and treatable disease
  • Characterized by airflow limitation
    • Usually progressive
    • Associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases
  • Exacerbations and comorbidities contribute to the overall severity in individual patients

2

Definitions

  • Chronic bronchitis 
  • Emphysema 

  • Chronic bronchitis
    • Defined clinically as the presence of chronic productive cough for 3 months during each of two successive years in a patient in whom other causes of chronic cough have been excluded
    • Airflow limitation is not a required feature for the diagnosis of chronic bronchitis.
  • Emphysema
    • Defined anatomically as abnormal, permanent enlargement of the air spaces distal to the terminal bronchioles accompanied by destruction of their walls

3

Under-reporting of COPD symptoms by patients

  • Many smokers deny their symptoms because they are not motivated to stop smoking
  • Lungs have a generous reserve of function
    • Shortness of breath does not become prominent until a large proportion of lung function has been lost (about 50%)
  • Respiratory function is lost gradually
    • Patients adapt to a restricted level of activity and attribute their impairment to normal ageing

4

Mortality of COPD

  • 3rd leading cause of death in the US
  • Accounts for more than 120,000 deaths annually
  • Prevalence and impact have been increasing for several decades following the epidemic of cigarette smoking in the twentieth century
  • Mortality may be peaking among men in the United States, but among women, mortality continues to rise
    • Deaths from COPD among women now exceed those among men in the US

5

Risk factors for COPD:
Exposure to toxic fumes and gases

  • Cigarette smoking
  • Environmental air pollution, especially particulates

  • Cigarette smoking
    • The most important exposure risk factor for COPD
    • Smokers lose lung function in a dose-dependent manner
      • Some individuals lose lung function at a much more accelerated rate than others
    • Only 10-15% of smokers develop clinically significant COPD
      • Many more may have impaired lung function that is not clinically apparent
  • Environmental air pollution, especially particulates
    • May contribute to an accelerated decline in lung function
    • Episodes of increased pollution may contribute to acute mortality

6

Risk factors for COPD

  • Asthma
  • Mucus hypersecretion and exacerbations
  • Perinatal and childhood effects

  • Asthma
    • Accelerated loss of lung function among asthmatics
      • May be that all of the risk is in a subset of asthmatics
    • At least in some cases, asthma can progress to fixed airflow obstruction
  • Mucus hypersecretion and exacerbations
    • Mucus hypersecretion has a modest effect
    • Individuals who experience more frequent acute exacerbations appear to have a more rapid decline in lung function
  • Perinatal and childhood effects
    • Strong correlation between childhood respiratory infections and the development of COPD

7

Natural history of COPD

  • Maximally attained lung function
  • Over 50 years of adult life, a normal lung may...
  • Smoking during the years of lung growth
  • Variation in the rate of lung function decline among individuals

  • Maximally attained lung function
    • Reached in young adulthood
    • Remains relatively constant for perhaps 10 years
    • Begins to decline in a slowly accelerating manner
  • Over 50 years of adult life, a normal lung may...
    • Lose 1 liter of FEV1, a decline that averages 20 mL/year
  • Smoking during the years of lung growth
    • Reduces maximally attained lung function
    • The "plateau phase" is reduced in duration and may be absent
    • The rate at which lung function declines is probably also increased by smoking
  • Variation in the rate of lung function decline among individuals
    • The 2-year mortality rate for patients admitted to hospital for an acute exacerbation with carbon dioxide retention is about 50%
    • Some patients with severe obstructive airway disease survive for many years
    • Thus, it is not possible to predict the course of an individual with a high degree of certainty

8

Pathogenesis of COPD:
Inflammatory cells

  • In response to cigarette smoke,..
  • Causes of inflammation

  • In response to cigarette smoke,..
    • Neutrophils rapidly accumulate in the lung
    • This accumulation results in a significant oxidant burden to the lung due to...
      • The oxidants present in smoke
      • Oxidants generated by the recruited inflammatory cells
  • Causes of inflammation
    • Cigarette smoke (both directly and indirectly)
    • Analysis of end-stage lung tissue obtained from lung volume reduction surgery (later, a decade after smoking cessation

9

Pathogenesis of COPD:
The proteinase : antiproteinase hypothesis

  • A deficiency of serum alpha-1 antitrypsin, the endogenous inhibitor of neutrophil elastase, is associated with emphysema
  • Experimental animal models using intratracheal elastases result in air-space enlargement
  • Other matrix components, such as collagen, must also be lost for an alveolar space to enlarge
  • An imbalance of proteinases and antiproteinases can lead to emphysema

10

Pathogenesis of COPD:
Cell death and repair

  • Cell death
  • Repair

  • Cell death
    • Because cell viability requires cell-matrix attachment via integrins, loss of matrix disrupts the contact and predisposes to cell death
    • Non-inflammatory cell death can initiate air-space enlargement
  • Repair
    • In emphysema, alveolar and extracellular matrix (ECM) repair is impaired, resulting in...
      • Coalesced and enlarged air spaces with depleted and disordered parenchymal elastic fibers
      • Excessive, abnormally arranged collagen

11

Clinical features of COPD

  • Most frequent symptom
  • Most patients with COPD manifest...

  • Most frequent symptom
    • Cough
  • Most patients with COPD manifest...
    • Cough
    • Expectoration
    • Dyspnea
      • Usually causes patients to seek medical attention
      • Many patients avoid dyspnea by avoiding exertion and may become exceedingly sedentary
    • Sputum production is greater in smokers
      • Usually mucoid
      • Becomes purulent during infective episodes
      • May take 2 to 3 weeks to clear

12

Clinical features of COPD

  • In many patients with COPD, physical examination reveals...
  • The most consistent finding in patients with symptomatic COPD
  • As COPD becomes severe, other physical signs may become evident
  • Patients may be observed...

  • In many patients with COPD, physical examination reveals...
    • Little abnormality especially during quiet breathing
    • Rhonchi may be present during inspiration and expiration
    • Wheezing is not a consistent finding and does not relate to the severity of the obstruction
  • The most consistent finding in patients with symptomatic COPD
    • Prolonged expiratory time (longer than 4 seconds)
  • As COPD becomes severe, other physical signs may become evident
    • Barrel-shaped chest
    • Purse-lipped breathing
    • Emaciation
  • Patients may be observed...
    • Sitting forward and leaning on their elbows
    • Supporting their upper body with extended arms in a position known as tripodding

13

Clinical features of COPD:
Radiographic findings

  • Chest radiography 
  • Findings suggestive of chronic bronchitis
  • Findings suggestive of emphysema

  • Chest radiography
    • Can help exclude other pathology in patients with COPD
    • COPD is a functional diagnosis and chest radiographs can only suggest this diagnosis
  • Findings suggestive of chronic bronchitis
    • Increased thickness of bronchial walls viewed on end and an increased prominence of lung markings
    • Neither specific nor sensitive
  • Findings suggestive of emphysema
    • An arterial deficiency pattern, characterized by the triad of overinflation, oligemia, and bullae

14

Clinical features of COPD:
Radiographic findings

  • The best evidence of overinflation 
  • Computed tomography (CT) 

  • The best evidence of overinflation
    • Flattening of the diaphragms with a concavity of the superior surface of the diaphragm
    • Increase in the width of the retrosternal air space, but this is less sensitive
  • Computed tomography (CT)
    • Can resolve the pulmonary parenchyma much better than the standard roentgenogram
    • Can establish and quantify the severity of emphysema and its anatomic extent
    • Can also determine the presence of bullae and distribution of emphysema, which is important in selecting patients for surgical intervention

15

Clinical features of COPD:
Pulmonary function testing:
Spirometry

  • Procedure
  • Diagnostic of obstruction
  • Suggestive of asthma excluding COPD
  • Helpful for defining therapeutic goals

  • Procedure
    • Patients take a maximally deep breath then exhale as forcefully as possible
    • The volume exhaled after 1 second, the FEV1, is the most important measure
    • The maximal volume exhaled is the forced vital capacity, or FVC
  • Diagnostic of obstruction
    • A reduction in the FEV1/FVC ratio (less than 70)
  • Suggestive of asthma excluding COPD
    • Correction to the normal range with bronchodilator treatment
  • Helpful for defining therapeutic goals
    • Partial correction, which may vary from day to day in an individual patient

16

Clinical features of COPD:
Pulmonary function testing

  • Total lung capacity 
  • Residual volume 
  • Functional residual capacity
  • Vital capacity
  • Single-breath diffusing capacity 

  • Total lung capacity
    • Increased in emphysema because the loss of elastic recoil permits the lungs to stretch to a greater maximal volume
  • Residual volume
    • May also be increased
  • Functional residual capacity
    • May also be increased
  • Vital capacity
    • May be decreased because the residual volume usually increases more than the total lung capacity
  • Single-breath diffusing capacity
    • Decreased in proportion to the severity of emphysema because of the destruction of the alveoli and loss of the alveolar capillary bed

17

Clinical features of COPD:
Arterial blood gases

  • Arterial blood gases show mild or moderate hypoxemia without hypercapnia in the early stages of COPD
  • In the later stages of the disease, hypoxemia tends to become more severe and may be accompanied by hypercapnia with increased serum bicarbonate

18

Complications of COPD:
Pneumothorax

  • Pneumothorax complicating COPD can precipitate severe dyspnea and acute respiratory failure and may be life-threatening
  • Pneumothorax should be suspected in any COPD patient who experiences sudden worsening of dyspnea

19

Complications of COPD:
Cor pulmonale

  • Chronic cor pulmonale is defined as enlargement of the right ventricle due to increased right ventricular afterload from diseases of the lungs or pulmonary circulation
  • The major cause of increased pulmonary vascular resistance in patients with COPD is vasoconstriction due to alveolar hypoxia
  • There is subsequent remodeling of the pulmonary vasculature

20

Complications of COPD:
Systemic manifestations

  • Skeletal muscle weakness, bone disease and weight loss may be associated with COPD
  • Metabolic alterations are thought to play a role in the pathogenesis of these systemic manifestations
    • There is likely a contribution from increased levels of circulating inflammatory cytokines such as tumor necrosis factor-α (TNFα) and interleukin-6 (IL-6)

21

Treatment of COPD

  • Smoking cessation
  • Medications
  • Oxygen therapy
  • Pulmonary rehabilitation
  • Surgical options
  • Long-acting bronchodilators
    • Include both anticholinergics (tiotropium) and beta2 agonists (salmeterol and formoterol)
    • Can maintain stability and pre-dose respiratory function, reduce exacerbation frequency, and improve quality of life
  • Inhaled steroids
    • Have a marginal effect on lung function
    • Reduce exacerbation frequency and improve quality of life
  • Continuous oxygen therapy in those that qualify
    • Can impact survival
    • Participation in pulmonary rehabilitation can have a major impact on functional capacity and quality of life
  • Surgical options
    • Lung volume reduction surgery
    • Lung transplantation

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