• Respiratory Auscultation

    Auscultation is one of the most important and effective clinical techniques for evaluating a patient's respiratory pathology. You will find description of various respiratory auscultation findings with audio examples in this article.

    Many of the audio examples here are recorded using the Littmann 3200 electronic stethoscope.

    This article has multiple pages, make sure you check them all out.

    Basics


    Let us start by looking at some requirements for an efficient auscultation:

    • A quiet environment is desirable as it makes it easier to listen to respiratory sounds.
    • The patient should be in the proper position, preferably in a sitting position, so that all the areas of chest are accessible for examination. However, the anterior areas can be examined even when the patient is lying down. In a patient who is not ambulatory or who is unable to sit up, posterior areas can be examined in a lateral postion (either left or right).
    • Stethoscope should be preferably touching the patient's bare skin. Auscultation through clothes should be avoided as far as possible. This is to avoid friction sounds that may cause confusion, especially with synthetic clothing. If the patient's chest is hairy, then moistening that chest with warm water might be helpful.
    • Always ensure patient comfort. Auscultation can easily be carried out while the patient is breathing normally. Requests for deep breathing should be as infrequent as possible, as they can tire the patient. Remember that we tend to examine the respiratory system of a patient in a great detail only when we suspect that he or she has a respiratory disease. It is inappropriate to expect that patient to breathe harder for a long time!

    While auscultating, THREE simple questions have to be answered:

    • Is the intensity of breath sounds increased, normal, or decreased?
    • Is the character of breath sounds normal or abnormal?
    • Are there any abnormal or adventitious sounds?

    Answers for all these questions should be documented along with the areas in which they are noticed.

    Mechanism of Breath Sound Production


    How are breath sounds produced?

    Breath sounds are produced in the major airways - trachea and major bronchi. It is a common misconception that these sounds are produced in the alveoli. But they are not. The velocity of air in the alveoli is not significant enough to produce turbulance and audible sounds.

    What is the character of the breath sound that is produced?

    You will know if you have auscultated at the trachea. It is bronchial breath sound. But aren't we told that the 'normal' breath sound is vesicular? YES!

    • The breath sound normally produced at the trachea is bronchial.
    • The breath sound normally heard on the chest wall, respiratory areas, is vesicular.

    Now, here is the explanation - The bronchial breath sounds produced at the major airways have to travel all across the tissues (through air in the bronchi, bronchioles, alveolar walls, etc) to reach the body surface from where they are auscultated. While they are being transmitted through these tissues, some (high) frequencies of sound are absorbed (attenuated) and the character of the sound changes. This changed (attenuated) sound is termed vesicular breath sound.

    If you remember this basic concept, we shall discuss about the genesis of abnormal sounds in each condition in subsequent pages of this article.

    Normal Breath Sounds


    Vesicular Breath Sounds


    This is the normal breath sound and is heard over most of the lungs. It is soft and low-pitched (low frequency) and the expiratory phase is shorter than the inspiratory phase. The expiratory phase is shorter because the breath sounds produced in the latter 2/3 of expiration are mainly composed of high-pitched sounds which are filtered out. It is compared in character to the rustling of dry leaves.

    Listen to this audio of vesicular breath sounds:




    The term vesicular breath sound was coined by Laennec, the inventor of the stethoscope. He named it so due to his belief that they were produced by air flowing through the alveoli.

    But it is not so. as we have learnt before in the previous page. We are dealing with a misnomer here.

    The
    mp3 audio clips used in this article can be downloaded from our downloads section. Please remember that these are for teaching-learning purposes only.
    Comments 39 Comments
    1. physiostudent's Avatar
      physiostudent -
      Greatly informative and takes you through the basics brilliantly.Cheersphysiostudent
    1. Christine's Avatar
      Christine -
      Brilliant. Studying pulmonary auscultation for a uni assignment. Great work
    1. Natasha's Avatar
      Natasha -
      thanks for the informative article.It tackles the nuances of resp auscultation in a very lucid manner.Good for beginners
    1. Manju CA, RN's Avatar
      Manju CA, RN -
      Excellent.It is a very good article for nurses to know about various Lung sounds.
    1. Mary's Avatar
      Mary -
      Wow, this is my dream come true... I want more auscultation explanations!
    1. Che's Avatar
      Che -
      Recommended site for identifying lung sounds. Thumbs up!
    1. Popcorn's Avatar
      Popcorn -
      Super Thank you!
    1. majid zakir's Avatar
      majid zakir -
      awesome...big help.
    1. pgv's Avatar
      pgv -
      thanx you very much,it's a great work.
    1. Paras bhardwaj's Avatar
      Paras bhardwaj -
      Thank you,Breath sounds explained here are really helpful.
    1. Luci's Avatar
      Luci -
      I find it incredibly difficult to distinguish between all of the above, so this was really helpful, thank you
    1. Mark's Avatar
      Mark -
      Daria loves this site and all articles
    1. Lew's Avatar
      Lew -
      Thanks for all the audio clips in this article. Best I have heard on the internet.
    1. ANIRUDDHA LAHA's Avatar
      ANIRUDDHA LAHA -
      THANKS for giving me such nice audio clips.
    1. Subhashini's Avatar
      Subhashini -
      Thanks for this wealth of information on breath sounds!
    1. Unregistered's Avatar
      Unregistered -
      Thank you - nurse working in minor illness - different doctors can use different terms for the same thing - was getting confusing! Great to have some clarity! Very helpful.
    1. klvn26's Avatar
      klvn26 -
      Thank you Sir for the explanations and sound clips..i still find it tough to differentiate them though...hopefully will be able to do so with experience, will work on it ^^
    1. Unregistered's Avatar
      Unregistered -
      Really great..
    1. Aneurysm's Avatar
      Aneurysm -
      What I love the most in your explanation is the attention to detail. You know what mistakes we commonly do as undergraduates and have focused on that... not many people write with this clarity. Please do write on more such topics. Thanks!
    1. erixo75's Avatar
      erixo75 -
      I'm a IMG preparing for USMLE step 2 CK, this is really useful for every year media questions are increasingly being incorporated. Thanks a million !
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