Rhonchi and Rales: What's the Difference?

Rhonchi and rales are lung sounds that can be heard with a stethoscope. Rhonchi are described as gurgling or bubbling sounds, while rales are described as crackling sounds. The sounds happen when air passes through accumulated fluids in the airways due to asthma, pneumonia, COPD, or other respiratory conditions.

The characteristics of lung sounds, including their pitch and whether they are heard on inhalation or exhalation, can offer clues as to the underlying cause.

This article looks at the causes of rhonchi and rales, how they differ, and what can be done to diagnose and treat them.

What Are Rhonchi?

Rhonchi are sometimes called sonorous wheezes (meaning that they sound like wheezing breaths). They are characterized by continuous, low-pitched breathing sounds that resemble snoring or gurgling. Rhonchi are heard during exhalation (when you breathe out) and are temporarily relieved by coughing.

Rhonchi are caused by the obstruction (blockage) of the larger airways of the lungs by fluid, mucus, or other secretions. These larger airways, known as bronchi and bronchioles, are supported by semi-circular rings of cartilage. The sound is created as air pockets pass roughly through the accumulated fluids.

Rhonchi are associated with obstructive lung diseases in which damage to the airways causes air to leave the lungs slower than it should as you exhale.

Examples include:

• Chronic obstructive pulmonary disease (COPD): This is a chronic, progressive lung disease that includes emphysema and chronic bronchitis.
• Bronchiectasis: This is the permanent widening of the bronchi and bronchioles.
• Asthma: This is a chronic disease that causes the airways to spontaneously narrow, swell, and produce extra mucus.
• Cystic fibrosis: This is an inherited disease in which the lungs and digestive tract produce too much mucus, blocking and damaging passages.
• Pneumonia: This is an infection of the lungs that causes tiny air sacs, called alveoli, to fill with fluid or pus.
  

What Are Rales?

Rales, also known as crackles, are small clicking, bubbling, or rattling sounds heard during inhalation (when you breathe in). They may either be high-pitched ("fine rales") or low-pitched ("coarse rales"), depending on the severity of the illness.

Rales are also caused by accumulated lung secretions but involve the alveoli rather than the larger airways. These air sacs are not supported by cartilage but are instead surrounded by lung tissues (called parenchyma). Certain diseases can cause the air sacs to collapse due to inflammation or scarring of these tissues.

Rales occur during inhalation when the air sacs suddenly snap open, causing a distinct crackling sound. Unlike rhonchi, rales are not relieved by coughing.

Rales are associated with restrictive lung diseases that mainly affect the parenchyma of the lungs. When these tissues are damaged, you cannot inhale as deeply as you should.

These include:

• Interstitial lung disease (ILD): This is an umbrella term used for a large group of diseases that cause scarring (fibrosis) of the lungs.
• Pulmonary edema: This is the swelling of the lungs due to the overload of fluid in tissues (sometimes referred to as "wet lung").
• Asbestosis: This is a condition that causes scarring of the lungs due to prolonged exposure to asbestos fibers in the air.
• Pneumonia: The infection can also cause parenchymal inflammation (sometimes referred to as "interstitial pneumonia").
• Idiopathic pulmonary fibrosis (IPF): This is a condition in which lung tissues become thick and stiff for unknown reasons.
  
• Sarcoidosis: This is a rare condition that causes small patches of granular tissue, called granulomas, to form in the organs of the body, including the lungs.
• Atelectasis: This is a condition that causes alveoli to collapse in certain areas of the lungs.
• Autoimmune diseases: Lupus and rheumatoid arthritis can both attack the lungs, causing the progressive scarring of lung tissues.

Rales can change as the underlying condition gets worse. Fine crackles are generally heard when the alveoli are affected, while coarse crackles are a sign that the larger airways are being affected. In severe cases, rales and rhonchi can be heard together.

Rhonchi vs. Rales: Key Differences

It can be hard to tell the difference between rhonchi and coarse rales. There are, however, some key differences:

Diagnosis

In addition to diagnosis, listening to breath sounds is a form of monitoring the progression of a respiratory condition. This section, however, will focus on the next steps that should be taken in pinning down a specific diagnosis after a healthcare professional identifies rhonchi or rales on auscultation.

It is worth noting that addressing any immediate breathing problems such as decreased oxygen saturation should be taken care of before obtaining diagnostic testing.

If you are experiencing rhonchi or rales for the first time, and the cause is unknown, some of the following diagnostic tests are usually beneficial in identifying the cause:

• Chest X-rays
• Sputum cultures
• Pulmonary function tests
• Bronchoscopy
• Heart studies (if heart failure is suspected)

Treatment for Rhonchi and Rales

There are no specific guidelines for the treatment of rhonchi or rales. The treatment is ultimately based on the underlying lung disease, broadly described as being either obstructive or restrictive. The resolution of the underlying cause will almost invariably ease the abnormal breathing sounds.

Rhonchi and Obstructive Lung Disease

Rhonchi are a feature of obstructive lung disease. Symptoms develop when there is either an acute flare-up of the disease (known as an exacerbation) or the onset of interstitial pneumonia.

Treatment measures may involve:

• Bronchodilators: Inhaled drugs like Proventil (albuterol) help relax the lungs and widen the airways.
• Inhaled steroids: Inhaled medicines like fluticasone reduce lung inflammation.
• Oral steroids: Oral drugs like prednisone provide rapid and sustained control of severe exacerbations.
  
• Antibiotics: These drugs are used either to treat bacterial pneumonia or prevent a secondary bacterial lung infection.
• Supplemental oxygen: This is used when you cannot get enough oxygen from regular breathing.
• Postural clearance: This technique is used to clear mucus from the lungs with a combination of huffing, coughing, and chest percussion.
• Singulair (montelukast): This is an oral drug used to prevent asthma attacks.

Rales and Restrictive Lung Diseases

Rales are associated with restrictive lung diseases and require many of the same treatments as obstructive lung diseases. With that said, the damage caused to the functional tissue of the lungs may require different interventions to improve breathing.

Depending on the severity of symptoms, the treatment may involve:

• Bronchodilators
• Inhaled steroids
• Oral steroids
• Supplemental oxygen
• Antifibrotics: Oral drugs like Ofev (nintedanib) and Pirespa (pirfenidone) can help slow lung scarring and damage caused by ILD.
• Immunosuppressants: Drugs like methotrexate or Imuran (azathioprine) can temper the immune response in people with autoimmune lung disease or severe sarcoidosis.
• Pulmonary rehabilitation: This is a supervised program that includes exercise training, health education, and breathing techniques.
• Lung transplant: This is a last-resort option for people with severe ILD or asbestosis.

Prevention

Rhonchi and rales can't always be avoided, but certain lung diseases that cause rhonchi and rales can be prevented with relatively simple measures.

Among some of the key tips:

• Stop smoking: Cigarette smoke increases the risk of almost every lung disease and can make symptoms worse. It can also increase your risk of getting pneumonia.
• Get vaccinated: There are many infections that cause pneumonia, some of which can be prevented with vaccines. These include the pneumococcal, flu, and COVID-19 vaccines. Keep on top of your recommended vaccine schedule, and catch up if you've fallen behind.
• Avoid triggers: If you have asthma, identify your triggers so that you can take steps to avoid an attack. These may include colds, allergies, smoke, fumes, aspirin, and stress. If you don't know your triggers, keep a diary to record every time you have an attack and what preceded them.
• Use your chronic medications: If you have COPD, severe asthma, or cystic fibrosis, taking your chronic medications as prescribed can prevent flare-ups and slow disease progression. This includes inhaled medications commonly used for all three conditions.

Summary

Rhonchi and rales are abnormal breathing sounds caused when air passes through accumulated fluids or secretions in the lungs.

Rhonchi occurs when you exhale, causing a low-pitched snoring or gurgling noise. The sound is caused by an obstruction in the airways and is associated with obstructive lung diseases like COPD, asthma, and cystic fibrosis. Coughing can temporarily relieve the abnormal lung sound.

Rales occur when you inhale, causing a low-pitched or high-pitched crackling noise. It is caused when collapsed alveoli suddenly snap open and is associated with restrictive lung diseases like interstitial lung disease and asbestosis. Coughing doesn't relieve the abnormal lung sound.