Bronchial breath sounds are distinct noises produced as air moves through the windpipe and larger airways. These sounds are characterized by their loud, harsh, and tubular quality. They are high-pitched, with a noticeable pause between the inspiratory (breathing in) and expiratory (breathing out) phases. The expiratory phase lasts longer and is louder than the inspiratory phase.
Normal Locations
Bronchial breath sounds are a normal finding when heard over specific areas where large airways are close to the surface. These include the trachea (windpipe) in the neck, and over the sternum (breastbone). Specifically, they are heard over the manubrium, the upper part of the sternum, and in the anterior chest near the second and third intercostal spaces.
On the back, these sounds are detected between the shoulder blades, over the vertebrae from C7 to T3, which corresponds to the main bronchi. These sounds are heard in these locations due to the direct proximity of large airways to the chest wall. Air flowing through these wide, central passages creates turbulent vibrations that are efficiently transmitted through dense tissue and bone to the surface.
Abnormal Locations and Their Significance
Hearing bronchial breath sounds in areas beyond their normal central locations, such as over the peripheral lung fields, is an abnormal finding. Normally, peripheral lung fields produce softer, lower-pitched vesicular breath sounds, generated by air moving through smaller airways and air sacs. When bronchial sounds are heard in these peripheral areas, it suggests a change in lung tissue that allows sound to be transmitted more efficiently from larger airways.
This increased sound transmission occurs when normal air-filled lung tissue becomes denser or filled with fluid. Conditions like pneumonia, where air sacs fill with inflammatory fluid, or pulmonary edema, involving fluid accumulation, can lead to this change. Other possibilities include atelectasis (a collapsed lung) or pulmonary fibrosis (scarring and increased density of lung tissue). These changes create a more solid medium, allowing loud, high-frequency sounds from central airways to travel to the chest wall without being muffled by healthy, air-filled lung tissue. The presence of bronchial breath sounds in abnormal locations indicates an underlying issue that warrants medical evaluation.
Listening to Breath Sounds
Listening to breath sounds, known as auscultation, is a diagnostic technique performed by trained healthcare professionals. They use a stethoscope, an instrument designed to amplify internal body sounds, to listen for specific characteristics of lung sounds. The stethoscope allows a clinician to assess the frequency, intensity, duration, and quality of sounds produced by air moving through the respiratory system.
During an examination, the healthcare provider places the stethoscope on various points across the chest and back, asking the patient to breathe deeply through their mouth. This systematic approach helps them compare sounds from different lung areas and identify deviations from normal. Interpreting these sounds requires extensive medical knowledge and training to differentiate between normal variations and those that may signal an underlying health condition. If one has concerns about their breathing sounds, consulting a medical professional for a proper diagnosis and guidance is advised.