Interpreting Breath Sounds

Respiratory therapists use a stethoscope to listen or auscultate lung fields during the patient assessment.

Unlike a cardiologist that is attempting to interpret cardiac arrhythmias, breath sounds are indicative to knowing the PULMONARY STATUS of the patient at that particular moment.
It can be an emergency intervention, or obtained during routine patient assessment.

Locations for Auscultation


So what is the therapist hearing?
First, let’s define the basics of Normal vs. Abnormal breath sounds.


NORMAL BREATH SOUNDS, also known as VESICULAR, should be equal or BILATERAL over both lung fields.
This should include all lung fields including the periphery or the lung borders.
The movement of the air should be low pitched quiet breathing, without any high pitched sounds or crackling.
In addition, normal BRONCHIAL sounds should ONLY be heard over the trachea and the bronchi.

and include the undesirable variations:







CRACKLES:  (they sound like rice krispies) also known as RALES; can indicate fluid or secretions (mucus)
Often a clinician will say the patient sounds “wet”.
There are 3 types of crackles that may indicate specific disease states;


COARSE CRACKLES: also called RHONCHI may indicate large airway secretions (trachea, main bronchus)
Patient may need to cough, or have their airway suctioned by the RT.
This might be from an respiratory infection that produces large amounts of mucus.


MEDIUM CRACKLES:     may indicate middle airway secretions (segmental to terminal bronchi)
Bronchial hygiene may be required.
This may include postural or positional drainage, chest percussive therapy (VEST),
vibration and PEP therapy,and cough insufflation/exsufflation therapy.

FINE CRACKLES:     also called moist crepitant rales may indicate fluid in the alveoli and small airways.
This can often be attributed to conditions like pulmonary edema and congestive heart failure.
Chronic fine crackles can also point to the development of ARDS, or acute respiratory distress syndrome.
Treatment including diuretics, positive inotropes ,oxygen therapy, and mechanical
ventilation may be needed.


Note: Crackles can also be heard with the improper placement of a tracheostomy tube.
Air may leak around the stoma, and crackling will be heard under the surrounding skin.
This is called subcutaneous emphysema.


WHEEZING:     a higher pitched sound from inflammation and bronchoconstriction in the airway
Unilateral is one sided and can be the result of a foreign body obstruction
(example: child choking on a grape)
Bilateral is equal sided and is usually the result of a bronchospasm
(example: severe asthma exacerbation)

STRIDOR:  A high pitched crowing sound on INSPIRATION caused by upper airway obstruction and swelling
Important: (Marked stridor is an emergency!)
May be above the epiglottis or supraglottic, due to epiglottitis.
May be below the epiglottis or subglottic, from a disease like croup or a difficult extubation
Foreign body aspiration of food or fluids may also cause stridor in addition to wheezing.
Treatment may include racemic epinephrine, suctioning, bronchoscopy, corticosteroids,
and intubation for severe cases.


can be detected over one of both lungs.
This is the most dangerous of all breath sounds!
May indicate apnea episodes from cardiac or respiratory arrest, severe air trapping, forms of shock including sepsis,
neurological and brainstem disorders, multi-organ failure, and expiration of the patient.
Can require cardiopulmonary resuscitation (CPR) and emergency care treatment with airway care.
Unilateral absent breath sounds may indicate a pneumothorax and flail chest.
Treatment may require needle decompression of excess air/fluid & or a chest tube.
Note: Patients  that have had a pneumonectomy may have minimal to no breath sounds
in the chest over removed portion of the lobe. It can be difficult to distinguish from crackles.


PLEURAL FRICTION RUB:   a coarse, grinding or rubbing sound similar to crunching
Often caused by inflammation of the pleura (visceral and parietal) moving against each other.
May be caused by pleurisy, lung carcinoma, and tuberculosis.
Treatment may include courses of steroids, antibiotics, or antiviral meds.