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Wednesday, October 20, 2010

Where to listen to lung sounds

A question I get quite a bit by nursing and respiratory students is where to listen to lung sounds. I have also learned that nursing schools and RT schools may teach a different method, depending on the experience of the teacher.

In this post, however, I will teach you the ideal way to listen to lung sounds. Note, however, that it is up to you to find the method that works best for you. As with anything in the medical field, it's an art based on a science, and therefore the final decision is up to the individual.

I notice a lot of nurses and doctors will tell you to take in a deep breath for each place the stethoscope is placed on your back. While this is a good method of hearing adventitious lung sounds, it's not the best way to listen.

Here is how I do it.

First, I tell the patient to breathe normal. This way you will hear how the lungs sound with normal breathing. Now you take your stethoscope and place it over the right base of the lung on the back of the patient. Then you listen to the left base. Then the right middle lobe. Then the right upper lobe, and then the left upper lobe. All of this while the patient is taking normal breaths.

Basically, all you want to do here is see if the lung sounds are equal on each side and if the air movement is normal, increased, or decreased.

Normal air movement: This is where you hear airflow throughout the lungs fields. If the patient is short of breath and you hear normal air flow, you can surmise there is a low chance of it being due to bronchospasm. However, you still cannot rule bronchospasm out.

Diminished lungsounds: If all the lungfields are diminished, this is often indicative of bronchospasm, loss of lung elasticity (emphysema) or other diseases that diminish air flow such as cystic fibrosis or pulmonary fibrosis. If in one lobe, it may be indicative of something blocking airflow in that lobe, such as pneumonia or lung cancer.

Increased air movement: Usually you will only hear increased air movement over one lobe of the lungs, and usually in the bases. This is indicative of fluid in that lobe. Note here that sound travels better through water, and sounds louder. This may be a sign of possible pneumonia or pleural effusion.

Equal air movement: If the air flow is the same on both sides of the lungs this is good. If airflow is diminished on the right and normal on the left, then you know you have some disease process going on and it's up to you and the doctor to determine what it is.

Bronchospasm: This is best heard during normal laminar flow, and this is why you will want the patient to breath normal. If you hear wheezes during normal breathing, chances are increased that it might be bronchospasm.

All of this should be done in only a few short moments.

Second you will want to place the stethescope back on the right base and tell the patient to take in a deep breath. During a deep breath you will hear other adventitious lung sounds, such as a cardiac wheeze, crackles, rhonchi and rhales. Or, better yet, the air movement will be good with no adventitious sounds.

Here you will hear any fine crackles you missed when the patient was taking in a normal respiration (alveoli popping open). You will also be more likely to hear rhonchi or secretions that are rolling around. This is because the deep breath causes more turbulence and this may knock secretions around.

Likewise, these secretions, or other fluid, are likely to cause a wheeze that is not a bronchospasm wheeze. This is where you will here your cardiac wheeze or your wheeze due to secretions sitting on the vocal cords. These wheezes are often audible.

If you hear a wheeze, particularly one that is audible or present with good air movement, you should then proceed to listen to the throat. If you hear a wheeze in the throat you do not have bronchospasm, but a throat wheeze (stridor) that is radiating throughout the lungfields.

You can work your way up the patients back by the standard stethoscope spots as shown in the picture. Yet, ideally, when you are having a patient take in deep breaths, all you have to do is listen to the bases. That's where you'll hear your crackles.

Hence, if you hear crackles during normal respirations, chances are you'll hear them during deep inspirations. And, if you hear crackles during normal respirations, chances are what you are hearing is secretions or fluid as opposed to fine inspiratory crackles.

Third, once you have listened to all the lung fields you will want to listen to the throat. If you hear a wheeze in the throat you know the wheeze is not bronchospasm. More than likely it's secretions sitting on or near the vocal cords. This often occurs with cardiac patients, such as CHF.

Likewise, many times if you hear a wheeze throughout the lungfields and you have good throat wheeze.

Fourth, use common sense. While good airmovement and a throat wheeze may increase the chance it's caused by secretions or fluid, it does not always rule out bronchospasm. I have heard COPD patients and asthma patients with a throat wheeze and good air movement.

Like I said, the medical field is an art based on a science.

Check out my lung lexicon for more on the lung sounds, or check out this post on how to listen to lung sounds. To learn how to hear bronchospasm, click here.


Unknown said...

Might want to edit. I don't think there is a left middle lobe to listen to.

Rick Frea said...

Yeah your right. I wrote this with a baby one arm typing with one finger. Tnanks.

auntie said...

great information, but spell check: hear, here, etc.