39. Causes and consequences of increased airway resistance - causes and consequences of chronic obstructive pulmonary disease (COPD) - emphysema

Characteristic of obstructive pulmonary disorders?

• non-elastic airway resistance is increased, mostly during expiration

  • can be due to extrathoracic or intrathoracic obstructions

what are extrathoracic obstructions ?

Inspiration is hampered, while expiration is mostly normal

often accompanied by stridor, a high-pitched sound on inspiration

• post-intubation hardening of the trachea

• compression of the trachea

  • goitre

  • tumor

  • laryngeal spasm

COPD?

progressive airway obstruction that may be partially be reversible

which two diseases belong to the COPD group?

chronic bronchitis

emphysema

which three criteria is used for diagnosing COPD?

FEV1 < 80% of predicted FEV1

Tiffeneau index (FEV1/FVC) < 70%

Airway obstruction not completely reversible upon administration of bronchodilator

what can COPD lead to?

chronic global respiratory failure

chronic bronchitis?

characterized by increased bronchial secretion, chronic cough and enhanced sputum production

what can cause chronic bronchitis?

• Active, chronic smoking (90% of cases)

• Occupational dust exposure

  • Silicosis

• α1 antitrypsin deficiency (most important inherited factor)

• Air pollution (smog)

• Blood group “A”

• Vitamin C deficiency

• Alcoholism

By which mechanisms does cigarette smoke damage the airways?

contains many compounds that damage the airways → e.g. polycyclic aromatic hydrocarbons which:

• damages the mucociliary clearance

• causes neutrophil inflammation of airways

• hyperplasia of goblet cells

  • increased mucous secretion

• promotes metaplasia of mucosa

• inhibits the function of Lys-oxidase

how does cigarette smoke induce lung inflammation?

activates tissue macrophages in the lungs → attract and activate neutrophils

→ neurophils release neutrophil elastase and collagenase enzymes which break down the parenchyme

what does airway inflammation by neutrophils cause?

edema and hyperplasia of the bronchial wall, which obstructs the bronchi

which enzyme has a protective role against parenchyme destruction by neutrophils?

Lysoxidase

⍺1 antitrypsin?

acute phase protein

produced by the liver during systemic inflammation

serine protase inhibitor

main function: limit the damage caused by neutrophil elastase during inflammation

blue bloaters?

patients with chronic bronchitis → cyanotic makes them blue, bloaters as they are obese (often)

usually have an underlying primary alveolar hypoventilation

how can we treat chronic bronchitis?

by muscarinic antagonists (bronchodilators)

β2 agonists (bronchodilators)

theophylline

glucocorticoids (prednisone)

cause of emphysema?

primarily: ⍺1 antitrypsin def

secondary: smoking

centrilobular emphysema?

occurs in smoking

panlobular emphysema?

⍺1 antitrypsin def.

emphysema pathomechanism?

The proteases degrade and destroy the elastic fibres in the alveolar septa. This decreases the elastic recoil of the lung, meaning that the passive process of expiration becomes harder.

Lung compliance becomes abnormally high. Destroyed elastic fibres also lead to some alveoli collapsing at expiration.

Because the alveolar septa are destroyed is the risk that bullas can burst very high. If this happens pneumothorax occurs.

risk factors for developing asthma?

• Obesity

• Male gender

• Overenthusiastic hygiene

  • Few infections during childhood

  • No exposure to bacteria or parasites

• Bad diet

which factors can trigger an asthma attack?

• Allergens

  • Perfume

  • Pollen

  • House dust mites

  • Mold

  • Aspirin

    • 3-5% of people with asthma can have asthma attacks triggered by aspirin

  • Smoking

• Infections

• Exercise

• Air pollution

• Stress and anxiety

how can we reduce asthma symptoms?

By administering:

• β2-agonists by inhalation

• Anticholinergic drugs (muscarinic M3 antagonists)

• Corticosteroids by inhalation

• Theophyllin

bronchial asthma?

asthma

disease characterized by episoes of paroxysmal reversible bronchospasm including dyspnoea with wheezing

types of asthma?

intrinsic

• unkown etiology

• non-allergic type

extrinsic

• allergic type

• evoked by many antigens