Auscultation

Auscultation of the lungs is the most important examining technique for assessing air flow through the tracheobronchial tree. Together with percussion, it also helps the clinician to assess the condition of the surrounding lungs and pleural space. Auscultation involves (1) listening to the sounds generated by breathing, (2) listening for any adventitious (added) sounds, and (3) if abnormalities are suspected, listening to the sounds of the patient's spoken or whispered voice as they are transmitted through the chest wall.

Breath Sounds (Lung Sounds). You will learn to identify patterns of breath sounds by their intensity, their pitch, and the relative duration of their inspiratory and expiratory phases. Normal breath sounds are:

Sounds from bedclothes, paper gowns, and the chest itself can generate confusion in auscultation. Hair on the chest may cause crackling sounds. Either press harder or wet the hair. If the patient is cold or tense, you may hear muscle contraction sounds—muffled, low-pitched rumbling or roaring noises. A change in the patient's position may eliminate this noise. You can

■ Vesicular, or soft and low pitched. They are heard through inspiration, continue without pause through expiration, and then fade away about one third of the way through expiration.

■ Bronchovesicular, with inspiratory and expiratory sounds about equal in length, at times separated by a silent interval. Differences in pitch and intensity are often more easily detected during expiration.

reproduce this sound on yourself by doing a Valsalva maneuver (straining down) as you listen to your own chest.

■ Bronchial, or louder and higher in pitch, with a short silence between inspiratory and expiratory sounds. Expiratory sounds last longer than inspiratory sounds.

The characteristics of these three kinds of breath sounds are summarized in the table below. Also shown are the tracheal breath sounds—very loud, harsh sounds that are heard by listening over the trachea in the neck.

Characteristics of Breath Sounds

Duration of Sounds

Intensity of

Expiratory

Sound

Pitch of

Expiratory

Sound

Locations Where Heard Normally

Vesicular* Inspiratory sounds Soft ^f--- last longer than

Relatively low

Bronchovesicular

Bronchial

Tracheal

expiratory ones.

Inspiratory and expiratory sounds are about equal.

Expiratory sounds last longer than inspiratory ones.

Inspiratory and expiratory sounds are about equal.

Intermediate Intermediate

Loud

Very loud

Relatively high

Relatively high

Over most of both lungs

Often in the 1st and 2nd interspaces anteriorly and between the scapulae

Over the manu-brium, if heard at all

Over the trachea in the neck

If bronchovesicular or bronchial breath sounds are heard in locations distant from those listed, suspect that air-filled lung has been replaced by fluid-filled or solid lung tissue. See Table 6-5, Normal and Altered Breath and Voice Sounds (p. 240).

* The thickness of the bars indicates intensity; the steeper their incline, the higher the pitch.

Listen to the breath sounds with the diaphragm of a stethoscope after instructing the patient to breathe deeply through an open mouth. Use the pattern suggested for percussion, moving from one side to the other and comparing symmetric areas of the lungs. If you hear or suspect abnormal sounds, auscultate adjacent areas so that you can fully describe the extent of any abnormality. Listen to at least one full breath in each location. Be alert for patient discomfort due to hyperventilation (e.g., light headedness, faintness), and allow the patient to rest as needed.

Note the intensity of the breath sounds. Breath sounds are usually louder in the lower posterior lung fields and may also vary from area to area. If the breath sounds seem faint, ask the patient to breathe more deeply. You may then hear them easily. When patients do not breathe deeply enough or when they have a thick chest wall, as in obesity, breath sounds may remain diminished.

Breath sounds may be decreased when air flow is decreased (as by obstructive lung disease or muscular weakness) or when the transmission of sound is poor (as in pleural effusion, pneumothorax, or emphysema).

Is there a silent gap between the inspiratory and expiratory sounds?

A gap suggests bronchial breath sounds.

Listen for the pitch, intensity, and duration of the expiratory and inspiratory sounds. Are vesicular breath sounds distributed normally over the chest wall? Or are there bronchovesicular or bronchial breath sounds in unexpected places? If so, where are they?

Adventitious (Added) Sounds. Listen for any added, or adventitious, sounds that are superimposed on the usual breath sounds. Detection of adventitious sounds—crackles (sometimes called rales), wheezes, and rhonchi— is an important part of your examination, often leading to diagnosis of cardiac and pulmonary conditions. The most common kinds of these sounds are described below:

For further discussion and other added sounds, see Table 6-6, Adventitious (Added) Lung Sounds: Causes and Qualities (p. 241).

Adventitious Lung Sounds

DISCONTINUOUS SOUNDS (CRACKLES OR RALES) are intermittent, nonmusical, and brief—like dots in time

Fine crackles (-..--Coarse crackles ( » w * brief (20-30 msec).

) are soft, high pitched, and very brief (5-10 msec). * *) are somewhat louder, lower in pitch, and not quite so

CONTINUOUS SOUNDS are > 250 msec, notably longer than crackles—like dashes in time—but do not necessarily persist throughout the respiratory cycle. Unlike crackles, they are musical.

Wheezes (WWW ) are relatively high pitched (around 400 Hz or higher) and have a hissing or shrill quality.

Rhonchi (•J'flMy ) are relatively low pitched (around 200 Hz or lower) and have a snoring quality.

Crackles may be due to abnormalities of the lungs (pneumonia, fibrosis, early congestive heart failure) or of the airways (bronchitis, bronchiectasis).

Wheezes suggest narrowed airways, as in asthma, COPD, or bronchitis.

Rhonchi suggest secretions in large airways.

If you hear crackles, especially those that do not clear after cough, listen carefully for the following characteristics. These are clues to the underlying condition:

■ Loudness, pitch, and duration (summarized as fine or coarse crackles)

Fine late inspiratory crackles that persist from breath to breath suggest abnormal lung tissue.

■ Timing in the respiratory cycle

■ Location on the chest wall

■ Persistence of their pattern from breath to breath

■ Any change after a cough or a change in the patient's position Clearing of crackles, wheezes, or rhonchi after cough suggests that secretions caused them, as in bronchitis or atelectasis.

In some normal people, crackles may be heard at the lung bases anteriorly after maximal expiration. Crackles in dependent portions of the lungs may also occur after prolonged recumbency.

If you hear wheezes or rhonchi, note their timing and location. Do they change with deep breathing or coughing?

Transmitted Voice Sounds. If you hear abnormally located broncho-vesicular or bronchial breath sounds, continue on to assess transmitted voice sounds. With a stethoscope, listen in symmetric areas over the chest wall as you:

Increased transmission of voice sounds suggests that air-filled lung has become airless. See Table 6-5, Normal and Altered Breath and Voice Sounds (p. 240).

■ Ask the patient to say "ninety-nine." Normally the sounds transmitted through the chest wall are muffled and indistinct.

Louder, clearer voice sounds are called bronchophony.

'ee." You will normally hear a muffled long E

When "ee" is heard as "ay," an E-to-A change (egophony) is present, as in lobar consolidation from pneumonia. The quality sounds nasal.

■ Ask the patient to whisper "ninety-nine" or "one-two-three." The whispered voice is normally heard faintly and indistinctly, if at all.

Louder, clearer whispered sounds are called whispered pectoriloquy.

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  • Juuso
    Why is there a gap in inspiratory expiratory phase bronchial breathing?
    3 years ago

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