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Monday, March 28, 2016

Learning Basic Lungsounds

The following was written by me and published at on January 25, 2016

Lungs 101: Learning Basic Lung Sounds

I have been listening to lung sounds for 20 years now, and every so often someone wants to know what I heard and what it means. That said, here is a pithy lesson on the five basic lung sounds and what they mean. 

First, however, a few definitions. 

Auscultation: The process of listening to lung sounds.  It can be done ear to chest, although most health professionals prefer to use a stethoscope. 

Stethoscope: It's a medical device used to auscultate (hear) lung and heart sounds.

Listening to lung sounds is an important part of assessing a patient. Based on what is heard can help a caregiver both diagnose and treat patients, and determine the progression of lung diseases over time. 

There are basically only five lung sounds.  You'd think that would make listening to them easy, but that's not always the case considering every patient is different. Regardless, here are the basic five and what they might mean.

1.  Clear.
This is a normal lung sound. It means the airways are open and air is easily moving through airways.

2.  Diminished.
This means that air movement is difficult to hear. It's quite common for COPD patients to develop diminished lung sounds, perticularly in the bases, or in the lower lobes. This is most commonly found when emphysema is present, as there is less lung tissue to move air. Of course it may also be due to a COPD flare-up where airways are obstructed by bronchospasm and increased secretions. This may indicate a need for a bronchodilator (like albuterol).

3.  Rhonchi
This is the sound of air moving through secretions.  It is a low-pitched, continuous sound that is best heard on expiration. Some describe it as coarse lung sounds, as it sounds coarse. Some say it sounds like snoring. It's usually lower than a wheeze because it's occurring in the larger airways.  It is also sometimes audible, and sometimes occurs with gurgling. Quite often rhonchi clears up with a good cough. Since this is common among COPD patients, we often teach methods to make a cough more effective.

4.  Wheeze
This is a high-pitched continuous sound heard on inspiration, expiration, or both. It's most commonly heard on expiration, though.  It is the sound of air moving past an obstruction in the airway. This can occur in the large airways or smaller airways.  An obstruction in the larger airways may produce an audible wheeze.  However, obstructions in the smaller airways, as what occurs with asthma and COPD, will cause a wheeze that can only be heard by auscultation.  Wheezing is a symptoms of bronchospasm, and may clear up after using a bronchodilator.

5.  Crackles
This is often described as a discontinuous sound, like the sound of velcro being torn apart. It usually needs a further qualification.
  • Fine Inspiratory Crackles.  This is when the crackle is heard on inspiration. A cause might be the popping open of an air sac (alveoli) that had been collapsed. This is a common sound in the lung bases of people with COPD, and it can become a normal sound for them.  When crackles are heard in one lobe, this can be a sign of lobar pneumonia.
  • Coarse Crackles (Rhales):  This is when crackles are heard on inspiration and expiration, and is the sound of air moving through fluid.  The fluid can be excessive secretions the patient is unable to cough up, or it could be pulmonary edema caused by heart failure. It means that the lungs are wet (the patient has wet lungs). Usually, but not always, this lung sound is heard on both sides of the lungs equally, as fluid is not prejudiced to one side of the lung. 
People with asthma should have clear lungmsounds when their asthma is controlled, and between asthma attacks. You can have clear lungs ounds with COPD too.  After using a bronchodilator, diminished lung sounds may become clear.

Or, sometimes, as airways open up, wheezing may occur. This we consider good, as it means air is moving better, and so wheezing can now be heard. So, you see, wheezing can be good, too. So auscultating before and after rescue medicine usage is one tool we have to determine if it's working (a peak flow meter is another such tool). Of course another tool is you, because you can just tell us that you feel better.

Pneumonia is a common complication of chronic bronchitis.  Fine inspiratory crackles can often be heard before pneumonia shows up on an x-ray, allowing your physician to start treating you early. As the pneumonia improves the crackles may go away. So, in this way, you can see how auscultating lung sounds can show how your illness is progressing over time.

Keep in mind that lung sounds are subjective, so every person may describe them somewhat different. Still, the basic principles are the same. It takes some practice to be able to hear and describe the different lung sounds. Nonetheless, I hope this post gives you a little better idea of what lung sounds are and what they mean. 

To hear the lung sounds described above you can check out, "Auscultation Lesson." You can also check out UCLA's "Auscultation Assistant."

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