Auscultation of the lungs is used to diagnose lung disease and check lung function. This is done by listening to the lungs with a stethoscope.
What is auscultation of the lungs?
Auscultation of the lungs is used to diagnose lung disease and check lung function. This is done by listening to the lungs with a stethoscope. Auscultation of the lungs is an integral part of the physical examination. The stethoscope can be used to distinguish physiological (normal) breath sounds from abnormal, i.e. pathological breath sounds. The stethoscope head contains either a diaphragm or a funnel. The acoustic waves caused by the air currents in the lungs are picked up through these. The vibrations are transmitted through the air column in the stethoscope tube to the ear olives and thus to the examiner’s ear.
Function, effect, and goals
Auscultation of the lungs occurs primarily with the patient standing. In weak patients, the examination may also be performed while the patient is sitting with the upper body upright. The patient’s upper body should be completely free of clothing. Before the examination, the patient should cough briefly. This will loosen any viscous secretions that may be present in the lungs. During auscultation, the patient should breathe evenly and deeply. The stethoscope is placed on at least eight points in the area of the lungs. A side-by-side comparison is made. If a conspicuous sound is heard at one of the points, other points in the immediate vicinity are listened to. Auscultation is performed on the chest and back. Due to the anatomical position, the stethoscope should also be placed on the side of the chest. Auscultation phenomena are basically divided into physiological and pathological sounds. Physiological sounds are the normal flow sounds caused by air in the airways and lungs. These include tracheal breathing, which can be heard above the trachea. In the bronchial region, bronchial breathing is physiological. In the peripheral areas of the healthy lungs, vesicular breathing is audible, which occurs during the breathing process in the alveoli. It can usually be heard only during inspiration. However, in healthy, slender people and in children, it can also be heard during exhalation. Otherwise, hearing vesicular breathing during exhalation may also be a sign of infiltration of the lungs. A sure sign of infiltration and/or compaction of the lung tissue is the appearance of bronchial breathing in the peripheral areas of the lung. In fact, only vesicular breathing should be heard here. Compaction in the lung tissue directs vibrations from the bronchi to the periphery of the lung. Compaction and infiltration occur, for example, in pneumonia. A lung tumor can also lead to these sound transmissions. If infiltration is suspected, it can be tested with the bronchophony procedure. In bronchophony, the examiner places the stethoscope over the suspected infiltrated lung area and has the patient whisper the word “66.” In the case of infiltration, this word is then heard very sharply and hissing at the ear due to conduction. Another pathological phenomenon during lung auscultation is rales. Dry rales can be distinguished from moist rales and fine rales from coarse bubbles. Moist rales occur when thin fluid secretions are set in motion by the incoming and outgoing air. Small-bubble rales are said to occur when the secretion is in the small terminal branches of the bronchi. Coarse-bubble moist rales originate in the large bronchial branches. Causes of moist rales include pulmonary edema, bronchiectasis, bronchitis, and pneumonia. Dry rales, also called dry breath sounds, are caused by viscous secretions in the alveoli or bronchi. They are often audible as a whistling, wheezing, or humming sound and are occasionally titled stridor. Dry rales are characteristic of chronic obstructive pulmonary disease and bronchial asthma. In an asthma attack, these sounds are very audible; this is also referred to as an asthma concert. When the alveoli are stuck together with little secretion, crackling rales occur over the affected sections of the lungs. Crackling is audible in the initial and final stages of pneumonia.In the initial stage, this is referred to as crepitatio indux, and at the end of the pneumonia, crepitatio redux. Amphoric breathing, also known as cavernous breathing, occurs over large cavities. It sounds like blowing over the neck of a bottle. These caverns develop primarily in pulmonary tuberculosis.
Risks, side effects, and dangers
Auscultation of the lungs is an examination procedure that has no side effects and is inexpensive. Properly performed, auscultation allows for a quick and accurate examination result, which can then be verified by further imaging procedures. To avoid obtaining false results, attention should be paid to possible sources of error during the procedure. The patient’s upper body should be completely undressed. Articles of clothing can scratch the skin and thus convey supposedly pathological sounds via the stethoscope. The patient’s arms should hang down as loosely as possible and not be crossed in front of the chest. Again, scraping the arms and hands against the skin can produce sounds. Hair should be tied in a braid if possible. If hair comes into contact with the stethoscope, it will cause a loud and annoying crackling noise. The examination room should be at a pleasant temperature. If the undressed patient is cold, shivering can cause confusing background noises. Care should also be taken with the patient’s breathing. Many patients think they have to breathe in and out particularly forcefully. In extreme cases, this can lead to hyperventilation and even fainting.
