What can cause the rales sound during lung examination?

The presence of rales, or crackling sounds, during a lung examination is typically indicative of fluid in the alveoli, which are the small air sacs in the lungs. When fluid accumulates in these spaces, it disrupts normal airflow and creates the characteristic sound of rales. This fluid may be associated with conditions such as pulmonary edema, pneumonia, or congestive heart failure.

Rales occur because air bubbles travel through fluid in the alveoli, leading to the sudden opening of collapsed airways. This phenomenon creates the distinct crackling or popping sounds that healthcare providers listen for during auscultation. Therefore, fluid in the alveoli is the most direct and relevant cause of rales in lung examinations. Understanding this connection is crucial for identifying the underlying respiratory issues that a patient may be experiencing.