Mastering Respiratory Auscultation: The Clinical Skills Quiz

Wheezes are generated by air flowing through narrowed airways (like whistling). Because airways naturally narrow slightly during expiration, wheezes are typically heard in the expiratory phase first. This is the classic finding in asthma and COPD. They are distinguished from crackles (discontinuous) and rhonchi (low-pitched snoring).

Vesicular sounds are the expected finding over peripheral fields. If you hear Bronchial or Tracheal sounds in the periphery, it is abnormal (indicating consolidation). Bronchovesicular sounds are intermediate and are normally only heard near the sternum or between the scapulae.

This is a crucial concept in respiratory physiology. Breath sounds are generated by turbulent airflow in the large airways (trachea and major bronchi). Airflow in the distal alveoli is too slow and laminar to produce sound. The 'vesicular' sound we hear is actually the sound from the large airways that has been filtered and attenuated by the lung tissue.

Vesicular breath sounds are the 'standard' sounds of healthy lungs. They are soft, low-pitched, and continuous (like rustling leaves). The inspiratory phase is longer and louder than the expiratory phase because the lung tissue filters out the high-frequency sounds of expiration.

Listening through clothing is a common error that introduces friction artifacts, which can mimic crackles or rhonchi. For accurate diagnosis, the stethoscope diaphragm must be placed directly on the skin. Wetting chest hair with warm water can also help reduce friction noise in hirsute patients.

Crackles are short, discontinuous, non-musical sounds typically heard on inspiration. They are generated by two mechanisms: the explosive opening of small airways that were closed during expiration (Fine Crackles) or air bubbling through secretions (Coarse Crackles). They are distinct from the continuous musical sounds of wheezes.

Polyphonic wheezes consist of multiple musical notes heard simultaneously. This indicates that many airways of different sizes are narrowed at the same time. This generalized obstruction is the hallmark of conditions like Asthma or COPD. In contrast, a Monophonic wheeze (single note) suggests a single focal obstruction, such as a tumor or foreign body.

Stridor is a loud, high-pitched inspiratory sound heard best over the trachea. It indicates a critical narrowing of the upper airway (e.g., from a foreign body, anaphylaxis, or infection). Unlike wheezes (which are usually expiratory and lower in the chest), stridor is an immediate red flag for potential airway compromise.

Bronchial breath sounds are loud, high-pitched, and have a distinctive 'hollow' quality. A key identifying feature is the pause (gap) between inspiration and expiration, and the fact that the expiratory phase is as long as (or longer than) the inspiratory phase. While normal over the manubrium, hearing this over peripheral lung fields indicates pathology like consolidation.

Decreased breath sounds occur when airflow is blocked (Asthma, Atelectasis) or when something blocks sound transmission (Pleural Effusion, Pneumothorax, Emphysema). Pulmonary Edema, however, is typically characterized by the presence of crackles (added sounds) due to fluid in the alveoli, rather than the silence of decreased breath sounds.

Normally, the two layers of the pleura slide smoothly against each other. In conditions like Pleuritis, the surfaces become inflamed and roughened. The friction between these rough surfaces during breathing creates a 'creaking' or 'rubbing' sound, audible during both inspiration and expiration. It typically disappears if a pleural effusion develops, separating the layers.

Egophony (or 'goat voice') is a key sign of consolidation (e.g., pneumonia or effusion). When the patient says 'eeee', the consolidated lung tissue filters out lower frequencies but transmits higher frequencies effectively. This changes the sound heard through the stethoscope to a nasal, bleating 'aaaa'.

The term was coined by René Laennec, the inventor of the stethoscope. He believed the soft rustling sounds were produced by air entering the vesicles (alveoli). We now know this is physiologically incorrect—the sounds are generated in the larger airways—but the term 'vesicular' has persisted in medical terminology due to historical tradition.

In a normal lung, spoken words are muffled and indistinct because air-filled alveoli scatter the sound. In Bronchophony, the sound is transmitted clearly and loudly. This occurs because fluid or solid tissue (as seen in consolidation or pneumonia) conducts sound waves much more efficiently than air. If '99' sounds clear through the stethoscope, it suggests underlying pathology.

Squawks (also known as squeaks) are short, inspiratory wheezes that are almost always accompanied by crackles. They are distinct from rhonchi (low-pitched snoring sounds) or stridor (loud tracheal sounds). Squawks are typically associated with interstitial lung diseases like hypersensitivity pneumonitis, where the sudden opening of airways creates a short musical sound.