Flow limitation is a respiratory phenomenon where increasing the driving pressure for airflow does not result in a corresponding increase in air flow.
Understanding Flow Limitation
Based on the provided reference, Flow limitation occurs when increased esophageal pressure is not accompanied by a flow increase. This means that during breathing, even if the pressure difference driving air into the lungs increases (indicated by increased esophageal pressure), the rate of air flowing in remains constant or fails to rise further.
The Mechanics Behind Flow Limitation
The reference explains that the occurrence of flow limitation is tied to a dynamic interaction within the airway. Specifically, it depends on the interaction between:
- Negative pleural pressure: This internal pressure tends to cause the upper airway to collapse.
- Upper airway muscle activity: These muscles work to keep the airway open and counteract the collapsing force.
When this balance is disrupted, and the negative pleural pressure overcomes the ability of the airway muscles to maintain patency during inspiration, flow limitation can occur. The airway narrows, restricting airflow despite the increased driving pressure.
