Types of Breath Sounds

Breath sounds are heard over most of the lung fields. They consist of an inspiratory phase followed by an expiratory phase. There are four types of normal breath sounds:

Tracheal Bronchial Bronchovesicular Vesicular

Tracheal breath sounds are harsh, loud, high-pitched sounds heard over the extrathoracic portion of the trachea. The inspiratory and expiratory components are approximately equal in length. Although these sounds are always heard when the examiner listens over the trachea, they are rarely evaluated because they do not represent any clinical lung problems.

Bronchial breath sounds are loud and high-pitched and sound like air rushing through a tube. The expiratory component is louder and longer than the inspiratory component.

Figure 13-17 Technique for evaluating diaphragmatic motion. During inspiration (left), percussion in the right seventh posterior interspace at the midscapular line would be resonant as a result of the presence of the underlying lung. During expiration (right), the liver and diaphragm move up. Percussion in the same area would now be dull, owing to the presence of the underlying liver.

Figure 13-17 Technique for evaluating diaphragmatic motion. During inspiration (left), percussion in the right seventh posterior interspace at the midscapular line would be resonant as a result of the presence of the underlying lung. During expiration (right), the liver and diaphragm move up. Percussion in the same area would now be dull, owing to the presence of the underlying liver.

Figure 13-18 Placement of stethoscope heads. A, Correct placement of the diaphragm. Notice that the head is applied tightly to the skin. B, Placement of the bell. Notice that the bell is applied lightly to the skin.

These sounds are normally heard when the examiner listens over the manubrium. A definite pause is heard between the two phases.

Bronchovesicular breath sounds are a mixture of bronchial and vesicular sounds. The inspiratory and expiratory components are equal in length. They are normally heard only in the first and second interspaces anteriorly and between the scapulae posteriorly. This is the area overlying the carina and mainstem bronchi.

Vesicular breath sounds are the soft, low-pitched sounds heard over most of the lung fields. The inspiratory component is much longer than the expiratory component, which is also much softer and frequently inaudible.

The four types of breath sounds are illustrated and summarized in Figure 13-19.

Characteristic

Tracheal

Bronchial

Bronchovesicular

Vesicular

Intensity

Very loud

Loud

Moderate

Soft

Pitch

Very high

High

Moderate

Low

I:E ratio*

1:1

1:3

1:1

3:1

Description

Harsh

Tubular

Rustling but tubular

Gentle rustling

Normal locations Extrathoracic trachea Manubrium Over mainstem bronchi Most of peripheral lung

*Ratio of duration of inspiration to that of expiration.

Normal locations Extrathoracic trachea Manubrium Over mainstem bronchi Most of peripheral lung

*Ratio of duration of inspiration to that of expiration.

INSPIRATION EXPIRATION

Tracheal

Bronchial -

Bronchovesicular -

Tracheal

Bronchial -

Bronchovesicular -

Figure 13-19 Characteristics of breath sounds.

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