The points of auscultation are:
- Apical zone: just below the clavicles and above the cardiac silhouette (audible on the front and back);
- Mid zone: level of the hilar structures (audible on the front, sides and back);
- Lower zone: bases (audible on the sides and back).
The bell of the stethoscope is generally used to detect high-pitched sounds such as wheezing in the upper portions of the lung, while the diaphragm is used to detect low-pitched sounds throughout chest.
The optimal position for chest auscultation is with the patient sitting upright. However, the patient's clinical condition needs to be considered during the examination and for prone patients, access to the back is difficult, so you may shift your auscultation points to the lateral walls of the chest as close to the back as is practical.
The procedure
- Ensure your stethoscope has been cleaned and that you are wearing appropriate PPE
- Alert the patient to your intent and gain informed consent. Chest auscultation requires the chest and back to be exposed, so measures should be taken to protect the patient's privacy and dignity.
- Warm the chest piece of the stethoscope against your own skin (if cool) to avoid startling the patient.
- Position the ear tips in your ears so they point slightly forward (towards your nose).
- Place the chest piece of the stethoscope directly on the patient's skin using gentle pressure.
- On the front and back, listen to breath sounds for a full inspiration/expiration cycle on both sides of the chest at each level. This technique allows you to compare one side of the chest with the other in a systematic manner and detect any asymmetry.
- Start with the anterior chest in the Apical zone.
- On the back, methodically listen to the apices/upper zone, the mid lung fields and the base of the lungs. Avoid the scapula as lung sounds cannot be heard through bone.
- To assess the lateral chest start with the upper lobe move to the middle lobe, and finally the lower lobe at the bottom on the right hand side. Repeat on the left side noting that there are only two lobes (upper and lower lobe)
- Record the findings of chest auscultation in the patient record.
It is important to record:
- Locations auscultated – for example, "anterior, posterior and lateral chest assessed"
- Quality and location of sounds – If there are abnormal sounds, how loud were they, and where did you hear them?
Normal "Vesicular" breath sounds are the sound of the vocal cords vibrating during inspiration and expiration. These sounds are audible when listening to the chest with a stethoscope as they are transmitted through the bronchial tree. You should be familiar with them, and able to distinguish between baseline normal sounds and abnormal or adventitious breath sounds.
There are several abnormal/adventitious sounds but the main ones to be aware of are:
- Wheeze - a high pitched sound that often occurs on expiration, but can also occur on inspiration. Wheezing is often louder than usual breath sounds and in some patients it is audible from some distance or when the patient breathes through the mouth and indicates some degree of obstruction in the lower airways. Often associated with asthma or allergic reactions.
- Stridor - a harsher lower pitched sound than a wheeze and more usually heard on inspiration usually results from an upper airway obstruction such as laryngeal edema or the presence of a foreign body or secretions in the airways.
- Crackles - small "popping" sounds are generated within the small airways; they predominantly occur during the inspiratory phase as collapsed airways spring open, but can happen on expiration. Clinical conditions where crackles maybe present include pneumonia, pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), lung infection and heart failure.
- Absent breath sounds or a lack of audible breath sounds on auscultation are often caused by lung disorders that inhibit the transmission of sounds, for example, a pneumothorax, pleural effusion or areas of lung consolidation (fluid filling the alveoli). All these conditions prevent airflow reaching parts of the lung due to a pathological change in the function of the lung.
