COPD

Question 1

list some obstructive lung diseases

Answer 1

• chronic obstructive pulmonary disease (chronic bronchitis, empysema)
• asthma
• bronchiectasis
• small airway disease/ bronchiolitis

all instrinsic except emphysema which is parenchyma

Question 2

explain the mechanisms of abnormal gas exchange

Answer 2

normal arterial blood fas level depends on
- effectiency of alveolar ventilation, influences by airway resistance and pulmonary compliance (tissue resistance of lungs and chest wall)
- good pulmonary blood flow
- effective elaovelar capillary gas exchange
- matching of ventilation with perfusion
changes in aforementioned will result in abnormal gas exchange, leading to symptoms of respiratory disease

Question 3

what are the normal mechanisms of gas exchange

Answer 3

ventilation
perfusion
surface area
V/Q matching

Question 4

explain the mechanics of breathing in emphysema

Answer 4

• increased compliance - destruction of alveolar septa - decreased radial traction on broncoiles and descreased static recoil of lungs –> inspiratory muscles over inflate the lungs AND increased total lung capacity
• imbalance between recoil of thorax and lung - equal pressure point is reached earlier during expiration (intrapleural and intrathoacic pressures equilibrate earlier and increased FRC)
• compensatory overinflation - increased lung volume may help compensate (increased recoil and airway enlarge, decreasing airway resistance) and BUT hyperinflation –> lowering and flattening of the diaphragm (decreased effectiveness of abdominal pressure in breathing and diaphragm contracts less effieinctly)
• early airway closure - early closure –> air trapping –> increased residual volume

Question 5

explain the effects of chronic bronchitis on airway mechanics

Answer 5

normal compliance

early airway closure –> mucous plugging obstructs airflow during expiration