Lung sound auscultation is a fundamental skill in emergency medical services (EMS), involving the use of a stethoscope to listen to the airflow within a patient’s lungs. As an Emergency Medical Technician (EMT), this rapid, non-invasive assessment provides immediate insight into a patient’s respiratory status and the underlying cause of breathing difficulty. The ability to quickly and accurately assess lung sounds guides immediate treatment decisions. This article details the specific anatomical locations on the chest wall required for effective auscultation.
Clinical Rationale for EMT Auscultation
EMTs perform lung auscultation to identify or rule out life-threatening conditions that manifest as abnormal breath sounds. Wet, crackling sounds, often termed rales, in both lungs indicate the presence of fluid, highly suggestive of conditions like congestive heart failure (CHF) or pulmonary edema. This finding justifies the immediate use of interventions such as Continuous Positive Airway Pressure (CPAP) to help push the fluid out of the alveoli.
A high-pitched whistling sound, known as wheezing, is a sign of bronchospasm, where the lower airways are constricted, common in asthma or chronic obstructive pulmonary disease (COPD). Conversely, a complete absence or significant reduction of sound in one lung field suggests a severe lack of air movement, which could be the result of a collapsed lung (pneumothorax) following trauma. Recognizing these specific sound patterns provides the clinical justification for administering bronchodilators or preparing for advanced airway management. The assessment also determines the effectiveness of any respiratory treatments administered during transport.
Anterior and Lateral Auscultation Landmarks
The anterior and lateral chest sites are the most accessible for initial assessment, particularly when a patient is sitting upright or lying supine. To begin, place the stethoscope diaphragm just above the clavicle in the supraclavicular area to listen to the apex of the lungs. Moving inferiorly, the next placement should be in the second intercostal space, adjacent to the sternum, along the midclavicular line.
This positioning assesses the upper lobes of both the right and left lungs, allowing comparison between the two sides. The next points move down to the fourth intercostal space along the midclavicular line. This location is important on the patient’s right side, as it is the primary spot for listening to the right middle lobe.
The final anterior and lateral sites focus on the lower lung lobes, where fluid accumulation is often first heard. For the most inferior and lateral assessment, the stethoscope is moved to the sixth intercostal space along the midaxillary line. Assessing these points ensures all three lobes of the right lung and the two lobes of the left lung have been evaluated. The stethoscope must be placed directly on the skin, avoiding clothing and bony prominences.
Posterior Sites and Proper Auscultation Technique
While the anterior chest provides valuable information, the posterior surface offers the largest and most reliable area for listening to the lower lobes. The patient should be sitting upright, if possible, with their arms crossed in front or resting in their lap. This maneuver helps pull the scapulae away from the midline, exposing more lung tissue for auscultation.
The posterior assessment begins by listening to the lung apices just above the scapulae, near the mid-shoulder line. The EMT then follows a systematic ladder pattern, moving down the back and comparing the left side to the right side at each level. Placement must be positioned between the vertebral column and the medial border of the scapula, avoiding the bone which muffles sound.
The lower lobes are primarily heard from the posterior chest, assessed by listening from the T3 vertebra down to approximately the T10 level. At each point, the EMT must press the diaphragm firmly against the skin to create a seal and block environmental noise. Instruct the patient to breathe deeply through their mouth, as this increases air movement and makes subtle abnormal sounds easier to detect. The technique relies on comparing corresponding sites bilaterally, ensuring the EMT listens for a full inspiration and expiration cycle at every location.