When a healthcare provider listens to a patient’s chest with a stethoscope, they are listening for the sounds of air moving through the lungs. Normal breath sounds are soft and continuous, but various abnormal sounds indicate underlying respiratory issues. Two common abnormal sounds are rhonchi and wheezing. Understanding the difference between these two sounds is important because each points toward a distinct physiological problem within the air passages.
The Mechanics of Airflow Obstruction
The fundamental difference between rhonchi and wheezing lies in the nature and location of the physical obstruction causing the sound. Airflow obstruction in the lungs leads to turbulence, which produces the audible vibrations heard on the chest wall.
Rhonchi result from the movement of air through fluid, mucus, or thick secretions that have built up in the larger, more central airways, like the main bronchi. Air passing over this material causes the airway walls to vibrate, creating a low-pitched sound. Wheezing is caused by the actual narrowing or constriction of the small airways, known as the bronchioles, in the deeper parts of the lungs. This constriction forces the air through a much smaller opening, producing a high-pitched vibration of the airway walls themselves.
Rhonchi: Sound and Common Causes
Rhonchi are continuous, low-pitched sounds that resemble snoring, rumbling, or gurgling. The sound is often heard best during expiration, but it can sometimes be audible during both inhalation and exhalation. This low-pitched character results from the sound originating in the larger, more stable airways, which are supported by cartilage.
A distinguishing characteristic of rhonchi is that the sound can often change or temporarily clear after a strong cough. This happens because the physical act of coughing moves the thick mucus or secretions responsible for the obstruction. Rhonchi are frequently associated with conditions that produce excessive mucus, such as acute bronchitis, pneumonia, or Chronic Obstructive Pulmonary Disease (COPD).
Wheezing: Sound and Common Causes
Wheezing is a continuous, high-pitched sound that is often described as a whistle or a musical squeak. This high-pitched quality is caused by the extreme narrowing of the smaller airways, creating a rapid flow of air through a restricted space. Wheezing is most typically heard when a person exhales because the airways naturally narrow during this phase of the breathing cycle.
The underlying cause of wheezing is usually bronchoconstriction, which is the tightening of the muscles around the airways, or inflammation that causes the airway walls to swell. Asthma is the most common cause of wheezing, as it involves reversible episodes of airway inflammation and muscle spasm. Other common causes include COPD, severe allergic reactions, or a foreign object partially obstructing a lower airway.
When to Seek Medical Care
Any abnormal lung sound should be evaluated by a healthcare professional to determine the underlying cause and appropriate treatment plan. Certain symptoms, however, signal a severe restriction of airflow that requires immediate medical attention.
- Cyanosis, which is a bluish discoloration of the lips or fingernails, indicates dangerously low oxygen levels.
- Immediate care is necessary if a person is struggling to speak in full sentences due to shortness of breath or if they are breathing very rapidly and shallowly.
- For individuals with asthma, wheezing that does not improve after using a prescribed rescue inhaler is a sign of a life-threatening emergency.
- Other red flags include nasal flaring or the skin between the ribs pulling inward, known as intercostal retractions, which demonstrate the body is working excessively hard to breathe.