Breath Sounds: Abnormal Lung Sounds and Causes

Are you ready to learn about breath sounds, lung sounds, and auscultation? I sure hope so because that is what this study guide is all about.

As a Respiratory Therapist (or student), it goes without saying that you must fully know and understand auscultation and listening to lung sounds. This is also true for nursing and medical students as well.

The good news is — we created this study guide to help make the learning process much easier for you. So if you’re ready, let’s go ahead and dive right in.


Breath Sounds

What are Breath Sounds?

These are the sounds that come from the lungs during inhalation and exhalation that can be heard during auscultation.

When an abnormality is heard in a patient’s breath sounds, this indicates that other health issues may be present, such as:

  • Asthma
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Foreign body obstruction
  • Accumulation of fluid
  • Heart failure
  • Infection
  • Inflammation of the airways
  • Pneumonia

By listening to the quality, duration, and intensity of breath sounds, healthcare professionals can learn a lot more about a patient’s condition in order to provide the most appropriate forms of treatment.

What is Auscultation?

Auscultation is a simple, non-invasive procedure that involves the use of a stethoscope to listen to the sounds produced by the body. For the sake of this guide, we’re focusing specifically on the lungs.

A stethoscope amplifies the sounds within the lungs so that we can hear and have an idea of what’s going on with the patient’s condition.

When performing lung auscultation, the bell or diaphragm of the stethoscope is placed on the patient’s chest and/or back. Both sides can be compared with one another and the sounds of each lung should be compared as well.

Types of Breath Sounds:

Whether you’re a Respiratory Therapist, student, or even if you’re a nurse or a part of a different medical profession, knowing the types of breath sounds is extremely important.

Especially for Respiratory Therapists and physicians, but arguably just as important for nurses and other professions as well.

1. Vesicular (Normal)

Vesicular is just another name for normal breath sounds. They are low-pitch sounds that you would expect to hear as air flows through an open airway.

The sounds are usually soft and can be heard throughout both the inspiratory and expiratory phases of breathing.

2. Crackles (Rales)

Crackles, also known as rales, are short, explosive, lung sounds that are commonly heard in the small or middle airways of the lungs.

When crackles are heard during auscultation, it can be associated with fluid or secretions in the lungs. Crackles can occur on both inspiration and expiration but are more common during the inspiratory phase.

There are Two Types of Crackles:

  • Fine crackles
  • Coarse crackles

Fine crackles indicate that fluid is in the smaller airways. They have a higher frequency and a shorter duration. These are often heard in patients with CHF and pulmonary edema and can be treated with diuretic medications such as Lasix.

Coarse crackles are lower in pitch and longer in duration. They are caused by secretions in the large airways. They’re often referred to as Rhonchi, which we’ll talk more about in just a bit.

3. Wheezes

Wheezes are high-pitched abnormal breath sounds that are heard as air flows through a narrowed airway. They sound kind of like a whistle and are most audible during the expiratory phase of breathing.

If bilateral wheezing is heard in both lungs, this is an indication of bronchoconstriction which can be treated with a short-acting bronchodilator like albuterol.

When wheezes are heard in only one lung, this is referred to as unilateral wheezing which indicates that a foreign body obstruction is present. In this case, a bronchoscopy is indicated. Wheezes are also heard when patients are fluid overloaded, as with CHF and pulmonary edema.

4. Rhonchi

Rhonchi is an abnormal breath sound that can be heard when air moves through larger airways that have excess amounts of mucus or secretions.

These lung sounds are often low-pitched and are audible during the expiratory phase. The main difference between rhonchi and wheezes is that rhonchi sounds are low and dull while wheezes are high and squeaky.

As a Respiratory Therapist, when you hear rhonchi, you should recommend suctioning or bronchial hygiene therapy.

5. Stridor

Stridor is a high-pitched lung sound that is heard when an upper airway obstruction is present. It is most often heard during the inspiratory phase of breathing.

Several medical conditions can cause stridor, including the following:

  • Croup
  • Epiglottitis
  • Post-extubation laryngeal edema
  • Foreign body aspiration

It can be treated with cool mist and racemic epinephrine. And in severe cases, which would be considered as a medical emergency, intubation and mechanical ventilation would be indicated.

6. Diminished Breath Sounds

These are lung sounds that are heard when there is decreased air movement in the lungs.

It’s common for patients with COPD or an acute asthma attack to have diminished breath sounds because they aren’t moving much air in and out of the lungs.

Then, after a bronchodilator is administered, if you listen to their breath sounds again, you’ll often hear wheezes. This is actually sign that the patient has improved because the bronchodilator is working and has opened up the airways some.

7. Pleural Friction Rub

A pleural friction rub is a loud grating sound that is heard over the lungs when inflamed pleura rub together. It is caused by decreased levels of fluid in the pleural space.

This lung sound is often heard in patients with pleurisy.

What are Vesicular Breath Sounds?

As mentioned earlier, vesicular breath sounds are another name for normal breath sounds. They are low-pitched and basically sound as you would expect air to sound as it flows through an open airway. 

The sounds are usually soft and can be heard throughout both phases of the breathing cycle.

What are Adventitious Breath Sounds?

Adventitious breath sounds are the abnormal sounds that occur over the lungs and airways during auscultation.

Adventitious breath sounds are commonly associated with a wide array of heart and lung conditions. The type, duration, location, and intensity of each adventitious breath sounds can help medical professionals diagnose and treat medical conditions.

This is why knowing the differences between each type of abnormal breath sound is so important for healthcare practitioners. 

What are the Causes of Abnormal Breath Sounds?

There are several causes of abnormal breath sounds. Each of which is specific to the type of breath sound the patient is experiencing.

We covered a few already, but let’s go through a few more of the specific causes of abnormal lung sounds.

  • Crackles – Lung sounds that are caused by air moving through secretions of the small or middle airways.
  • Wheezes – Lung sounds that are caused by air moving through a narrowed or constricted airway.
  • Rhonchi – A lung sound that is caused by air moving through secretions in the larger airways.
  • Stridor – A lung sound that occurs when an upper airway obstruction is present.
  • Diminished – Present when there is decreased air movement in the lungs.
  • Pleural Friction Rub – A lung sound that is heard when inflamed pleura rub together due to decreased levels of fluid in the pleural space.

There are hundreds of causes of abnormal breath sounds — these are just a few of the common examples that you should be familiar with.

What is the Treatment for Abnormal Breath Sounds?

Abnormal breath sounds are often associated with common and treatable medical conditions. As a Respiratory Therapist or medical professional, you will be required to recommend the proper medication or treatment method for each of the different types of abnormal lung sounds. 

Here are the Common Treatment Strategies for Abnormal Breath Sounds:

1. Metered-Dose Inhaler (MDI)

This is a pressurized inhaler that delivers a bronchodilator (dilates the airways), corticosteroid (suppresses inflammation), or a combination of both.

By opening the airways and suppressing the inflammatory process, it can help restore breath sounds to normal.

2. Nebulizer

This is a device that delivers an aerosolized form of medication into the alveoli of the lungs via inhalation. They are commonly used to deliver bronchodilator medications, like albuterol, which can alleviate bronchoconstriction. 

Nebulizers can help deliver other medications as well which can treat other types of abnormal breath sounds.

3. Incentive Spirometry

This is a simple, inexpensive, and effective tool that is useful in helping a patient achieve normal lung function. This device mimics natural sighing or yawning, which in turn improves lung expansion and gas exchange.

To use the device, the patient needs to place the mouthpiece spirometer in their mouth and perform deep breathing exercises.

4. Chest physiotherapy (CPT)

This is also considered a simple and effective method of normalizing abnormal breath sounds. CPT includes various techniques in order to naturally clear lung secretions through the use of vibration (or shaking), proper positioning, breathing exercises, and coughing techniques.

5. Antibiotics

Antibiotic therapy is designed to fight infections and destroy microorganisms that affect lung functionality. By fighting the infection, antibiotics also help with airway inflammation and secretions which can improve abnormal breath sounds.

Keep in mind that there are many different types of treatment for abnormal lung sounds. These are just a few common examples that you should be familiar with.

What are Bronchial Breath Sounds?

Bronchial breath sounds are hollow lung sounds that can be heard in both normal and abnormal conditions. These sounds are normal when heard over the trachea, however, they are abnormal when heard over the lung fields.

For example, let’s say you’re auscultating a patient and hear bronchial breath sounds over the right lower lobe. This is a common finding in patients with pneumonia and it indicates that consolidation is present.

What are Bronchovesicular Breath Sounds?

Bronchovesicular breath sounds are normal sounds that are heard in the mid-chest area or over the scapula. Unlike other normal breath sounds, bronchovesicular breath sounds have tubular quality.

These sounds are the combination of bronchial breath sounds heard near the trachea and vesicular sounds in the alveoli.

Bronchovesicular breath sounds have equal periods of inhalation and exhalation, so the I:E ratio is typically 1:1. However, the differences in pitch and intensity are often audible during the expiratory phase.

What are Diminished Breath Sounds?

As previously mentioned, diminished breath sounds are soft, distant lung sounds with a lower volume and intensity. These sounds are often present in patients with decreased lung volumes.

They are also present in patients with severe obstructive conditions. That isn’t to say that this is always the case. There are several causes of diminished breath sounds.

Here are Some Examples:

  • Obese patients
  • Patients with increased muscle mass
  • Patients with air or fluid around the lungs
  • Patients with an increased chest wall thickness
  • Patients with lung hyperinflation

Each of these examples make it more difficult to hear lung sounds during auscultation which is the root cause of the diminished classification. 

Also note that during diminished breath sounds, the inspiratory phase is usually much longer than the expiratory phase. This means that a patient with diminished breath sounds will have an I:E ratio of 3:1. In other words, the inspiratory phase of breathing is three times longer than the expiratory phase. 

When are Coarse Breath Sounds Heard?

Coarse breath sounds are actually a type of crackles (rales). They are clicking, bubbling, or rattling sounds that occur during the inspiratory phase of breathing when air moves through secretions that have accumulated in the larger airways.

Coarse breath sounds are typically loud and low-pitched and are longer in duration. Most patients with copious amounts of secretions exhibit coarse breath sounds during auscultation of the affected lung area.  

When are Pneumonia Breath Sounds Heard?

Pneumonia is a respiratory infection caused by harmful microorganisms and is characterized by consolidation and a productive cough. Patients with pneumonia often have greenish or yellowish secretions which, again, are indicative of an infection. 

If a patient has pneumonia, you will likely hear crackling, bubbling, or rumbling sounds during auscultation. Wheezing is also a possibility is some areas of the lungs as well.

Crackles in patients with pneumonia are often heard only on one side of the chest or when the patient is lying down. In addition to crackles and wheezes, low-pitch rhonchi sounds may also be audible during the expiratory phase of breathing.

Additionally, as previously mentioned, bronchial breath sounds are also commonly heard in patients with pneumonia.

What are Stridor Breath Sounds?

Stridor is a high-pitched lung sound that is typically created by an upper airway obstruction. It is mostly audible during inhalation but can also be heard during exhalation in patients with a deteriorating condition.

These sounds commonly occur in extubated patients as a complication of endotracheal intubation. In children, stridor is very audible when they are lying on their back in the supine position.

Other causes of stridor include croup, pertussis, aspiration, epiglottis, choking, severe anaphylactic shock, tonsillitis, laryngitis, lung cancer, deviated septum, and blood transfusion reactions.

How to Perform Auscultation?

Auscultation is a technique that is used to listen to and examine the heart and lungs. It can also be used in the abdomen and other areas of the body with major blood vessels as well. But for the sake of this article, we’re focusing strictly on the lungs.

In order to assess a patient’s lung sounds, auscultation must be performed using a stethoscope in order to hear the sounds as the patient breathes. Let’s go through the process of performing auscultation on a patient.

Here are the Steps for Performing Auscultation:

1. Explain the procedure to the patient to establish trust and rapport.
2. Stand close to the patient in order to gain access to the target area. In this case, the target area is the lungs.
3. If the diaphragm (face) of the stethoscope is cold, warm it by rubbing the surface to avoid startling the patient.
4. Place the eartips of the stethoscope in your ears and adjust them as desired. They should fit comfortably and snuggly in your ears.
5. Hold the diaphragm of the stethoscope firmly against the patient’s skin with a moderate amount of pressure. Instruct the patient to take slow, deep breaths through an open mouth.
6. As the patients breathes, listen to the sounds and try to identify their intensity, location, strength, pattern, and duration.
7. Always listen to the patient’s anterior side first. Start at the apices and then move downward towards the lung bases. Then repeat the process on the posterior side.
8. Compare the right lung to the left lung. Also compare the anterior to the posterior side.
9. Document the findings in the patient’s chart.

What is the Best Stethoscope for Auscultation?

In order to perform auscultation and listen to breath sounds effectively, you need to get your hands on a high-quality stethoscope. The 3M Littmann Classic III is hands down our favorite and is also our top recommendation for medical professionals and students.

While this one is hands-down our favorite, there are plenty of other high-quality stethoscopes on the market that deserve consideration as well.

Now that you have a good understanding of breath sounds and auscultation, let’s take it a step further by going through some more practice questions on this topic.

Dr Rohit Bhaskar, Physio
Dr Rohit Bhaskar, Physio Dr. Rohit Bhaskar, Physio is Founder of Bhaskar Health and Physiotherapy and is also a consulting physiotherapist. He completed his Graduation in Physiotherapy from Uttar Pradesh University of Medical Sciences. His clinical interests are in Chest Physiotherapy, stroke rehab, parkinson’s and head injury rehab. Bhaskar Health is dedicated to readers, doctors, physiotherapists, nurses, paramedics, pharmacists and other healthcare professionals. Bhaskar Health audience is the reason I feel so passionate about this project, so thanks for reading and sharing Bhaskar Health.

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