Lung Auscultation

Listening to the Lungs
The lungs are auscultated with the diaphragm on the chest piece of a stethoscope with the patient breathing slowly and deeply thorugh their mouth. The anatomical sites for lung auscultation are illustrated in below.













There are some common errors to avoid:
Listening to breath sounds through a patients gown or clothes.
Allowing tubing to rub against bed rails or patient’s clothes.
Interpreting chest hair sounds as adventitious* sounds.
Auscultating on the convenient places only

*Adventitious sounds: added sounds, or those superimposed on a patient's underlying breath sounds that usually indicate disease.

Normal breath sounds consist of those heard over the entire lung field and consist of an inspiratory and expiratory phase. They are classified as:

1. Tracheal: These breath sounds are high-pitched and loud, with a harsh and hollow (or "tubular) quality. The inspiratory and expiratory phases are of equal duration, and there is a definite pause between phases. Tracheal breath sounds usually have very little clinical usefulness.



2. Bronchial: Normally heard over the upper manubrium, these breath sounds directly reflect turbulent airflow in the main-stem bronchi. They are loud and high-pitched but not quite as harsh and hollow as tracheal breath sounds, the expiratory phase is generally longer than the inspiratory phase, and there is usually a pause between the phases.



3. Bronchovesicular: These breath sounds are normally heard in the anterior first and second intercostal spaces and posteriorly between the scapulas, where the main-stem bronchi lie. The inspiratory and expiratory phases are about equal in duration, with no pause between phases. Bronchovesicular sounds are soft and less harsh than bronchial breath sounds and have a higher pitch than vesicular sounds.



4. Vesicular: Audible over peripheral lung fields, these breath sounds are soft and low-pitched, without the harsh, tubular quality of bronchial and tracheal breath sounds. The inspiratory phase is about three times longer than the expiratory, with no pause between phases .

Breath sounds are considered abnormal if they are heard outside their usual location in the chest or if they are qualitatively different from normal breath sounds (e.g. decreased or absent). They are divided into two categories: (1) continuous; and (2) non-continuous lung sounds.

Continuous adventitious sounds are referred to as wheezes and described as either high-pitched or low pitched.Wheezes represent airway obstruction which can be caused by broncho-constriction of smooth muscle or the presence of mucus. When a wheezes occur, it is significant. They are most common with expiration. However, they can occur during inspiration and this indicates that a severe airway obstruction is present.

Discontinuous adventitious sounds are classified as either:
1. Crackles(rales) sound like brief bursts of popping bubbles. They are most commonly associated with the sudden opening of closed airways.

2. Pleural Rubs are an indication of pleural inflammation and sounds like two pieces of sandpaper rubbing together throughout each inspiration and expiration

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