Abnormal Breath Sounds

Crackles are bubbling or popping sounds that represent the presence of fluid or secretions, or the sudden. Crackles therefore are best heard during the first deep breaths at the lung bases posteriorly. Right and left cranial lung lobes. Lung crackles are abnormal breath sounds heard with a stethoscope during a physical exam. Crackling in the lungs usually reflects a buildup of fluid, mucus.

Abnormal breath sounds include:

• the absence of sound and/or
• the presence of 'normal' sounds in areas where they are normally not heard.
  • For example, bronchial (loud & tubular) breath sounds are abnormal in peripheral areas where only vesicular (soft & rustling) sounds should be heard. When bronchial sounds are heard in areas distant from where they normally occur, the patient may have consolidation (as occurs with pneumonia) or compression of the lung. These conditions cause the lung tissue to be dense. The dense tissue transmits sound from the lung bronchi much more efficiently than through the air-filled alveoli of the normal lung.

The term “adventitious” breath sounds refers to extra or additional sounds that are heard over normal breath sounds. Sources differ as to the classification and nomenclature of these sounds, but most examiners commonly use the following terms to describe adventitious breath sounds.

• pleural friction rubs

Detection of adventitious sounds is an important part of the respiratory examination, often leading to diagnosis of cardiac and pulmonary conditions.

Crackles (or rales) are caused by fluid in the small airways or atelectasis. Crackles are referred to as discontinuous sounds; they are intermittent, nonmusical and brief. Crackles may be heard on inspiration or expiration. The popping sounds produced are created when air is forced through respiratory passages that are narrowed by fluid, mucus, or pus. Crackles are often associated with inflammation or infection of the small bronchi, bronchioles, and alveoli. Crackles that don't clear after a cough may indicate pulmonary edema or fluid in the alveoli due to heart failure or adult respiratory distress syndrome (ARDS).

• Crackles are often described as fine, medium, and coarse.
• Fine crackles are soft, high-pitched, and very brief. You can simulate this sound by rolling a strand of hair between your fingers near your ear, or by moistening your thumb and index finger and separating them near your ear.
• Coarse crackles are somewhat louder, lower in pitch, and last longer than fine crackles. They have been described as sounding like opening a Velcro fastener.

Listen to crackles at the University of Loyola's website (courtesy of Dr. David Cugell, Northwestern University and the American College of Chest Physicians.)

Crackles at The R.A.L.E.® Repository, courtesy of Dr. Pasterkamp

Wheezes are sounds that are heard continuously during inspiration or expiration, or during both inspiration and expiration. They are caused by air moving through airways narrowed by constriction or swelling of airway or partial airway obstruction.

• Wheezes that are relatively high pitched and have a shrill or squeaking quality may be referred to as sibilant rhonchi. They are often heard continuously through both inspiration and expiration and have a musical quality. These wheezes occur when airways are narrowed, such as may occur during an acute asthmatic attack.
• Wheezes that are lower-pitched sounds with a snoring or moaning quality may be referred to as sonorous rhonchi. Secretions in large airways, such as occurs with bronchitis, may produce these sounds; they may clear somewhat with coughing.

Listen to wheezes at the University of Loyola's website (courtesy of Dr. David Cugell, Northwestern University and the American College of Chest Physicians.)

Wheezes at The R.A.L.E.® Repository, courtesy of Dr. Pasterkamp

Pleural friction rubs are low-pitched, grating, or creaking sounds that occur when inflamed pleural surfaces rub together during respiration. More often heard on inspiration than expiration, the pleural friction rub is easy to confuse with a pericardial friction rub. To determine whether the sound is a pleural friction rub or a pericardial friction rub, ask the patient to hold his breath briefly. If the rubbing sound continues, its a pericardial friction rub because the inflamed pericardial layers continue rubbing together with each heart beat - a pleural rub stops when breathing stops.

Listen to a pleural rub at the University of Loyola's website (courtesy of Dr. David Cugell, Northwestern University and the American College of Chest Physicians.)

Stridor refers to a high-pitched harsh sound heard during inspiration.. Stridor is caused by obstruction of the upper airway, is a sign of respiratory distress and thus requires immediate attention.

If adventitious sounds are heard, it is important to assess:

• their loudness,
• timing in the respiratory cycle,
• location on the chest wall,
• persistence of the pattern from breath to breath, and
• whether or not the sounds clear after a cough or a few deep breaths.
  • secretions from bronchitis may cause wheezes, (or rhonchi), that clear with coughing
  • crackles may be heard when atelectatic alveoli pop open after a few deep breaths

Listen to stridor at the University of Loyola's website (courtesy of Dr. David Cugell, Northwestern University and the American College of Chest Physicians.)

Stridor at The R.A.L.E.® Repository, courtesy of Dr. Pasterkamp

Instant Feedback:

Rhonchi are discontinuous popping sounds heard during inspiration.

The Lung Auscultation Course from the University of Loyola includes self evaluation case studies. Explore this excellent resource!