Abnormal Breathing Sounds Types, Meaning and Causes

The passage of air through the main respiratory airways of the lung produces breathing sounds with every inspiration (inhaling of air into the lungs) and expiration (exhaling the air in the lungs). These sounds can either be soft and inaudible (as is the case of a resting or sleeping person), or loud and clearly audible (like after exercise). These changes in the volume and nature of the breathing sounds are normal and not a cause for concern. However, when the noises are loud, unusual in nature or sound like distress then it has to be investigated by a medical professional to identify the underlying cause.

What are abnormal breathing sounds?

The pitch and loudness of the sounds produced during breathing depend on the velocity of the air moving in and out of the bronchi (the major respiratory tubes through which the air reaches the lungs), as well as the condition of the airways through which the air is flowing. Any obstruction to the flow of air through the airways of the lungs results in abnormal breathings sounds.

These abnormal sounds, also known as adventitious breathing sounds, can be detected by placing a stethoscope over the chest region (a process known as auscultation). Sometimes, these sounds are loud enough to be heard without a stethoscope. The quality of the abnormal breathing sounds can help in the diagnosis of the primary underlying problem in the respiratory tract.

Types of Abnormal Breathing Sounds

There are multiple types of abnormal breathing sounds produced in various conditions. Some of the common abnormal breathing sounds are described below:

  1. Wheezing: Wheezing is a high-pitched, whistling sound that is a common feature of abnormal respiratory conditions like asthma and chronic obstructive pulmonary diseases (COPD). Wheezing sounds can usually be heard while exhaling the air during the breathing cycle.Wheezing sounds are caused by an obstruction to the airflow caused by the constriction of the lung airways. The obstruction to the air flow could result from the presence of a solid mass within the airways, presence of a mucus plug, or an allergic spasm of the bronchial walls.
  2. Stridor: They are high-pitched whistling sounds that are monotonous in nature. These abnormal breathing sounds are often confused with wheezing. Unlike wheezing, however, stridor is usually heard during the inspiration phase of the breathing cycle. Stridor is caused by an obstruction to the flow of air in the upper respiratory tract. The obstructed regions commonly include the trachea and the pharynx. Inflammation of these structures (example, in tracheitis, laryngitis, pharyngitis) is usually the culprit. Sometimes, paralysis of the vocal cords or obstruction due to a foreign object might also produce stridor.
  3. Crackles or rales: Crackles or rales are crackling, popping, clicking, bubbling or rattling noises made during inspiration. Based on the characteristics of the sound, crackles are classified as dry or moist, and fine or course. These abnormal sounds can be heard in conditions such as bronchiolitis, pulmonary edema, pulmonary fibrosis, asthma, tuberculosis, bronchitis, pneumonia and COPD. Usually, auscultation using a stethoscope is needed to be able to hear these sounds.
    Crackles or rales are thought to occur due to the sudden opening of closed or collapsed airways by the inspired air. In addition, the bubbling sounds are a result of the inspired air mixing into the mucus secretions accumulated in the airways.
  4. Pleural friction rub: This is a creaking sound that is produced when the pleural membranes lining the lung cavity rub against each other during breathing movements. This sound is usually associated with pain during breathing. The sound can be confused with the pleuropericardial rub, in which the pleural membrane rubs against the pericardial membrane surrounding the heart. The abnormal sounds due to pleural friction rub are found in conditions such as pleuritis, pleural fibrosis, mesothelioma, pneumonia, abscess in the lungs and pulmonary infarction. Usually, a stethoscope is required to hear these sounds properly.
  5. Pneumothorax click: This refers to the abnormal clicking sound heard when the pleural membranes near the heart rub against each other with each heart beat. It is caused by the uncoupling of the lung from the chest walls due to an abnormal accumulation of air in the space between the pleural membranes. Usually, the clicking sounds are also accompanied by chest pain and shortness of breath.
  6. Stertor: Stertor is the term used to describe the coarse sounds of snoring or gasping that are caused by partial closure of the upper respiratory airways in the pharynx region. This abnormal breathing sound is frequently found in obstructive sleep apnea. Stertor usually occurs when the affected individual is in deep sleep.

Meaning of Abnormal Breathing Sounds

As described, there are different kinds of abnormal breathing sounds that result from different causes. The presence of these sounds means that there is some disturbance in the airway or lungs, although there are instances where it can arise from surrounding structures and be mistaken for a respiratory problem.  Abnormal breathing sounds can either be temporary (example, a foreign object stuck in the airways, mucus accumulation in common cold and other conditions) or chronic (example, asthma and COPD).

Abnormal breathing sounds are caused by various factors such as physical obstruction of airways, mucus aggregation, inflammation of airways, infections, and accumulation of fluid in the lungs. Regardless of the nature of the abnormal breathing sounds, it is advisable to get further tests done to find the underlying cause and begin appropriate therapeutic measures. Especially in cases where sudden and severe breathing difficulties arise, one is advised to immediately rush to the doctor.

Treatment for Abnormal Breathing Sounds

In case of medical emergencies, such as occlusion of airways by a foreign object or severe difficulty in breathing, treatment is aimed at first restoring normal breathing activity. For example, in breathing difficulties caused by asthma attacks or anaphylactic reactions, it is imperative to counter the potentially lethal allergic reactions and restore normal breathing.

In non-emergency conditions, the physician will first take a detailed history of the respiratory and other accompanying symptoms. A physical examination, especially auscultation with a stethoscope, is then conducted to decipher the nature of the abnormal breathing sounds. The characteristics of the abnormal breathing sounds can help the physician in determining the exact underlying cause.

Further tests would then be prescribed to establish the potential cause of the abnormal breathing sounds. These tests can include blood tests, sputum tests, X-rays, pulmonary function tests and CT-scans. A specific line of treatment is then decided upon in order to deal with the underlying primary condition that is causing the abnormal breathing sounds.

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