When a healthcare professional listens to the lungs with a stethoscope, they assess the quality of air movement, which reveals valuable diagnostic information. Normal breath sounds are quiet, but the presence of adventitious sounds signals a potential problem within the airways. Rhonchi are common abnormal sounds, originating from air turbulence within the larger respiratory passages. Recognizing this specific sound is important for identifying an underlying respiratory illness.
Defining Rhonchi: Description and Characteristics
Rhonchi are continuous, coarse, and rumbling sounds produced during the breathing cycle. They are often compared to a deep snore or a gurgling noise, sometimes described as a low-pitched moan. These prolonged sounds are distinct from the short, popping noises known as crackles. Rhonchi are typically heard over the larger airways of the lungs, such as the main bronchi.
Classified as a continuous adventitious sound, rhonchi last for at least 250 milliseconds or longer. They may be audible during both inhalation and exhalation, though frequently more prominent during the expiratory phase. The low-pitched nature of the sound helps clinicians differentiate it from the higher-pitched whistle of a wheeze.
The Physiological Mechanism of Rhonchi Production
The sound of rhonchi is generated when air is forced to move through a partially blocked or narrowed large airway. This obstruction alters the smooth, laminar flow of air, causing it to become chaotic and turbulent. The resulting turbulent airflow creates vibrations in the airway walls and the thick secretions that are causing the blockage.
Because the obstruction is occurring in the wider-diameter bronchi, the air column is relatively large, which produces a lower-frequency, or low-pitched, sound. The obstruction is most frequently caused by a buildup of viscous material, such as mucus or fluid, lining the inner walls of the air passages. Bronchospasm, or muscle contraction in the airway walls, can also contribute to the narrowing and turbulent flow.
Common Underlying Conditions Associated with Rhonchi
Rhonchi are a direct indicator of excessive secretions within the large conducting airways. Several conditions cause this buildup of mucus or fluid that partially obstructs the air pathway:
- Acute bronchitis: An inflammation of the bronchial tubes is a frequent cause, where the body produces thick mucus in response to an infection.
- Chronic Obstructive Pulmonary Disease (COPD): Features persistent inflammation and hypersecretion of mucus that permanently narrows the airways. This chronic buildup creates a consistent environment for turbulent airflow and rhonchi production.
- Pneumonia: An infection that inflames the air sacs and can lead to rhonchi, particularly when the infection causes significant inflammation and fluid accumulation in the larger bronchi.
- Cystic fibrosis: A genetic disorder causing the body to produce unusually thick, sticky mucus that readily clogs the airways.
Clinical Significance and Next Steps
The most significant clinical feature of rhonchi is their tendency to be movable, or changeable, with a directed cough. Since the sound is caused by secretions within the larger airways, a strong cough often dislodges or moves the mucus. This movement can temporarily clear the obstruction, resulting in a reduction or disappearance of the rhonchi sound upon re-auscultation.
The ability of the sound to clear with a cough helps distinguish rhonchi from fixed sounds, like wheezes, which are caused by airway wall narrowing that is not easily moved. Management focuses on treating the underlying cause and helping the patient clear secretions.
Increased hydration is often recommended to thin the mucus, making it easier to mobilize and cough up. Directed coughing techniques can also maximize the efficiency of secretion clearance. Depending on the diagnosis, medication may be necessary, such as bronchodilators to open the airways or mucolytics to further thin the mucus. If rhonchi are accompanied by symptoms like fever, shortness of breath, or a persistent, worsening cough, a medical professional should be consulted immediately for a full diagnosis and treatment plan.