Question

• Reducing the distance from alveolus to the EPP is an indication of healthy lungs. T/F • Determining the position of the EPP is clinically important. T/F • EPP is an anatomical site that exists in both healthy individuals and patients with airway obstruction disease. T/F • Negative pressure in the airways is generated upstream the EPP. T/F . Effort-independent flow phenomenon occurs upstream the EPP. T/F . During forced expiration, the airway pressure increases downstream towards the mouth. T/F • There is a tendency for airway collapse below the EPP. T/F • EPP does not exist in healthy individuals. T/F FALSE • What happens to compliance when elastic recoil decreases? The opposite (increases)

Answer 1

Reducing the distance from alveolus to the EPP is an indication of healthy lungs. False

Air flow resistance in the airway causes pressure generated in the alveoli to drop. An equal pressure point (EPP) is formed when airway pressure equals to intraplerual pressure during expiration. At the EPP, airways that are not supported by cartilage will collapse.

In healthy lungs, the EPP will be reached in cartilaginous airways as a result of sufficient alveolar driving pressure and minimal airway resistance (the distance from alveolus to the EPP is greater).

In the case of airway obstruction, resistance to airflow will be much greater, and the pressure drop will be much steeper. The EPP will move upstream toward the alveoli and will be reached in the thin-walled bronchioles, causing airway collapse (the distance from alveolus to the EPP is lesser than the healthy lung).

Determining the position of EPP is clinically important. True

Yes, determining the position of EPP is clinically important. It’s not a problem if the EPP occurs in cartilaginous airways. However, the occurrence of EPP in the bronchioles near to alveoli could lead airway collapse and may lead immediate medical attention.

EPP is an anatomical site that exists in both healthy individuals and patients with airway obstruction disease. True

Yes. EPP exists in both healthy individuals and patients with airway obstruction disease. But the only difference it where it occurs. In healthy lungs, the EPP will be reached in cartilaginous airways and in patients with airway obstructions EPP will move upstream and will be reached in the thin-walled bronchioles, causing airway collapse.

Negative pressure in the airways is generated upstream the EPP. False

No. Negative pressure is not generated upstream the EPP. The pressure generated in the alveoli decrease due to resistance as the air moves down the air way and leading to the formation of EPP. Further pressure drop may be observed downstream the EPP.