Auscultation is a fundamental technique in healthcare that involves listening to the internal sounds of the body, typically using a stethoscope. This non-invasive procedure assesses a patient’s respiratory health by evaluating the sounds of airflow through the trachea and bronchial tree. Correctly performing lung auscultation is a foundational skill for identifying normal function and detecting potential abnormalities.
Preparation and Proper Auscultation Technique
Before beginning the examination, it is important to ensure a quiet environment to accurately hear the subtle sounds of air moving within the lungs. The patient should preferably be sitting upright, which allows for better lung expansion and easier access to the posterior chest. If a patient cannot sit, they can be turned side-to-side while lying down to access the different lung fields.
The stethoscope’s diaphragm, the larger, flatter side, is generally used for lung sounds, as it is better suited for detecting the higher-pitched sounds of airflow. It is crucial to place the diaphragm directly onto the patient’s skin, avoiding clothing or hair, as friction can create inaccurate or confusing sounds.
The patient must be instructed to breathe deeply through their mouth, allowing the nurse to hear a full cycle of inspiration and expiration at each listening point. The nurse should coach the patient and allow them to set the pace to prevent dizziness or hyperventilation.
Key Anatomical Zones for Listening
The systematic approach to auscultation involves comparing symmetrical points on the left and right sides of the chest, moving from top to bottom. This side-to-side comparison allows for the immediate detection of differences in sound intensity or quality between the two lungs. The assessment covers the anterior, lateral, and posterior surfaces of the chest to evaluate all lung lobes thoroughly.
Anterior Chest Landmarks
Listening to the anterior chest is primarily focused on the upper and middle lobes of the lungs. The assessment begins at the apex of the lungs, slightly above the clavicles, or collarbones. The nurse then moves down the chest, listening over the second intercostal space to assess the upper lobes. Further down, the fourth intercostal space is an important area for evaluating the right middle lobe and the left upper lobe. Throughout the anterior examination, the stethoscope should be placed between the ribs. Avoid listening directly over the sternum, ribs, or breast tissue.
Lateral Chest Landmarks
The lateral, or side, chest surfaces provide the best access to the lower lobes of the lungs, often referred to as the bases. The examination moves from the axilla, or armpit, down to the lower rib cage along the midaxillary line. Listening points around the sixth intercostal space in the midaxillary region are particularly useful for assessing the right and left lower lobes. The patient may need to lift their arms or cross them over their chest to fully expose the lateral chest wall for proper stethoscope placement.
Posterior Chest Landmarks
The posterior chest is the largest area for auscultation and provides the most comprehensive view of the lower lobes. To optimize sound quality, the patient should lean forward with their arms resting in their lap or crossed over their chest. This positioning helps separate the scapulae, allowing the nurse to place the stethoscope directly on the chest wall.
The posterior examination starts just above the scapulae to listen to the lung apices. The nurse then proceeds in a ladder-like pattern, moving down the back between the spine and the scapula. The area between the seventh cervical vertebra (C7) and the tenth thoracic vertebra (T10) covers the upper lobes down to the extensive area of the lower lobes.
Understanding Basic Sound Categories
Once the correct locations are identified, the nurse listens for normal breath sounds and any additional, or adventitious, sounds. Normal breath sounds are categorized by their pitch, intensity, and location on the chest.
Vesicular sounds are soft, low-pitched, and breezy, heard over most of the peripheral lung fields, with inspiration being longer and louder than expiration. Bronchial sounds are loud, high-pitched, and hollow, heard over the trachea, with the expiratory phase being as long as or longer than the inspiratory phase. Bronchovesicular sounds have a medium pitch and intensity, with equal inspiration and expiration phases, and are typically heard over the main bronchi, such as between the scapulae posteriorly.
Adventitious sounds are abnormal noises that occur in addition to the expected breath sounds, often indicating a change in the airways or lung tissue.
- Crackles, also called rales, are brief, non-musical, popping sounds caused by the sudden opening of previously collapsed airways or the movement of fluid.
- Wheezes are continuous, high-pitched, musical sounds, typically heard on expiration, resulting from air being forced through narrowed airways.
- Rhonchi are low-pitched, continuous, snoring or gurgling sounds that may clear with a cough, suggesting secretions in the larger airways.
- Stridor is a high-pitched, harsh sound heard loudest over the neck, indicating an obstruction in the upper airway.