29. Basic mechanisms disturbing lung function – obstruction of the airflow in the airways – types. Main pathogenetic mechanisms, causing obstruction – bronchial inflammation, bronchial hyperresponsiveness, alveolo-capillary and bronchiolar destruction.

Basic mechanisms disturbing lung function – obstruction, types

• General mechanisms disturbing lung function:

1. Obstruction
2. Restriction
3. Pulmonary blood flow deficit
4. Altered control of breathing

Obstruction

• Caused by 3 mechanisms:

1. Bronchial inflammation
2. Bronchial hyper-reactivity
3. Alveolar wall destruction

• Extra work is required by the respiratory muscles to overcome the obstruction → increased energy consumption → increased O2 consumption by the muscles → less oxygen available for other organs → hypoxia in these organs
• There is also increased residual capacity as the obstruction affects more expiration than inspiration
• There is decreased functional capacity
• The obstruction can be:
• Extrathoracic = inspiratory dyspnea
• Intrathoracic = expiratory dyspnea