1.9 : Physical Assessment of the Respiratory Tract IV: Auscultation

Auscultation is a crucial component of the physical assessment of the respiratory tract. It offers valuable insights into airflow through the bronchial tree and potential lung obstructions. This process involves careful listening to breath, voice, and adventitious sounds, which can reveal a wealth of information about a patient's respiratory health.

Breath Sounds

Breath sounds are categorized into vesicular, bronchovesicular, and bronchial.

• Vesicular sounds are soft, low-pitched, and rustling, typically heard over all lung areas except the major bronchi. They have a 3:1 ratio, with inspiration three times longer than expiration.

• Bronchovesicular sounds are of medium pitch and intensity, heard over the mainstem bronchi on either side of the sternum and posteriorly between the scapulae. They exhibit a 1:1 ratio, with inspiration equal to expiration.

• Bronchial sounds are louder and higher-pitched and resemble air blowing through a hollow pipe. They have a 2:3 ratio and a gap between inspiration and expiration.

The location, quality, and intensity of these sounds provide vital clues about a patient's respiratory health. For instance, diminished or absent breath sounds may signal bronchial obstruction, pleural effusion, or tissue separation from the air passages.

Voice Sounds

Voice sounds, or vocal resonance, are produced in the larynx and transmitted to the thorax as they pass through the bronchi and alveolar tissue.

In normal physiology, voice sounds are faint and indistinct. However, respiratory pathologies that increase lung density, such as pneumonia and pulmonary edema, can alter this response.

Three distinct abnormal voice sounds are bronchophony, egophony, and whispered pectoriloquy. Bronchophony is characterized by intense and clear vocal resonance. At the same time, egophony involves distorted voice sounds, often transforming the sound of the letter "E" into a heard "A." Whispered pectoriloquy describes the ability to clearly and distinctly hear whispered sounds that should not usually be heard.

Adventitious Sounds

Adventitious sounds are additional, abnormal sounds that may indicate a condition affecting the bronchial tree and alveoli. These include crackles, wheezes, rhonchi, pleural friction rubs, and stridor.

• Crackles, also known as rales, are brief, popping lung sounds heard during inspiration. They can be fine or coarse and are caused by fluid in the small airways or alveoli, which is seen in conditions like pneumonia, heart failure, and pulmonary fibrosis.

• Wheezes are continuous sounds, usually heard during expiration, caused by narrowed airways from asthma, COPD, or bronchitis.

• Rhonchi are low-pitched, gurgling sounds that are often clear with coughing. They indicate secretions or obstructions in larger airways, as seen in chronic bronchitis and cystic fibrosis.

• Pleural friction rubs are low-pitched, grating sounds heard during both inspiration and expiration. They are caused by inflamed pleural surfaces rubbing together and are common in pleuritis, pulmonary embolism, and infections like pneumonia.

• Stridor is a high-pitched sound heard over the neck, indicating a narrowing of the upper respiratory tract. This sound warrants emergent attention due to its potential implications for patient safety.

In conclusion, auscultation provides a comprehensive assessment of the respiratory tract, enabling healthcare professionals to diagnose and monitor respiratory conditions effectively. Carefully analyzing breath sounds, voice sounds, and adventitious sounds can reveal subtle changes in a patient's respiratory health, facilitating early intervention and treatment.