Wheezing (rhonchi) is a breathing noise caused by narrowing of the airways or the presence of pathological contents in them. Wheezing occurs mainly in the bronchi, less often in cavities that have a bronchial connection (cavity, abscess).
Since wheezing is caused by rapid air movement, it is best heard at the beginning of inhalation and at the end of exhalation. The mechanism of wheezing consists of two components.
- The presence in the lumen of the bronchi of more or less dense masses driven by an air stream.
- Changes in the condition of the bronchial wall, and therefore their lumen, for example, narrowing of the bronchial lumen, which may be a consequence of the inflammatory process and spasm. This circumstance can explain the frequent appearance of wheezing in bronchitis, broncho-obstructive syndrome and bronchial asthma.
Rene Laennec described the phenomenon, which he called wheezing, as follows: “In the absence of a more specific term, I used this word, designating as wheezing all the noises produced during breathing by the passage of air through all those fluids that may be present in the bronchi or lung tissue. These noises also accompany a cough when there is one, but it is always more convenient to examine them while breathing.”
Regardless of the type, wheezing occurs during inhalation and exhalation and changes when coughing. The following types of wheezing are distinguished.
- Dry wheezing in the lungs: low, high.
- Moist rales in the lungs: fine-bubble (voiced and unvoiced), medium-bubble, large-bubble.
Dry wheezing in the lungs
Dry wheezing occurs when air passes through the bronchi, in the lumen of which there is a fairly dense content (thick viscous sputum), as well as through bronchi with a narrowed lumen due to swelling of the mucous membrane, spasm of the smooth muscle cells of the bronchial wall or the growth of tumor tissue. Wheezing can be high and low, whistling and buzzing in nature. They are always audible throughout inhalation and exhalation. The level and degree of narrowing of the bronchi can be judged by the height of wheezing. A higher sound timbre (rhonchi sibilantes) is characteristic of obstruction of small bronchi, a lower one (rhonchi sonori) is noted when medium and large bronchi are affected. At the same time, the difference in the timbre of wheezing when bronchi of different calibers are involved is explained by different degrees of resistance to the air stream passing through them.
The presence of dry wheezing usually reflects a generalized process in the bronchi (bronchitis, bronchial asthma), so they are usually heard over both lungs. Determination of unilateral dry rales over a certain area, especially in the upper segments, as a rule, indicates the presence of a cavity in the lung (most often a cavity).
Moist wheezing in the lungs
When less dense masses (liquid sputum, blood, edematous fluid) accumulate in the bronchi, when an air stream passing through them produces a characteristic sound effect, traditionally compared to the sound of bursting bubbles when air is blown through a tube lowered into a vessel with water, moist rales are formed.
The nature of moist rales depends on the caliber of the bronchi where they occur. There are fine-bubble, medium-bubble and large-bubble rales, which occur in the bronchi of small, medium and large calibers, respectively. When bronchi of different sizes are involved in the process, rales of different sizes are detected.
Most often, moist wheezing is observed in chronic bronchitis, as well as in the stage of resolution of an attack of bronchial asthma; At the same time, fine-bubble and medium-bubble rales are not sonorous, since their sonority decreases when passing through a heterogeneous environment.
It is important to detect sonorous moist rales, especially fine-bubble ones, the presence of which always indicates that there is a peribronchial inflammatory process, and better transmission of sounds arising in the bronchi to the periphery is due in this case to compaction (infiltration) of the lung tissue. This is especially important for identifying foci of infiltration in the apex of the lungs (for example, with tuberculosis) and in the lower parts of the lungs (for example, foci of pneumonia against the background of blood stasis due to heart failure).
Voiced medium-bubble and large-bubble rales are detected less frequently. Their occurrence indicates the presence in the lungs of partially fluid-filled cavities (cavities, abscesses) or large bronchiectasis communicating with the respiratory tract. Their asymmetric localization in the area of the apexes or lower lobes of the lungs is characteristic of these pathological conditions, while symmetrical wheezing indicates stagnation of blood in the vessels of the lungs and the entry of the liquid part of the blood into the alveoli.
With pulmonary edema, moist coarse rales can be heard at a distance.
Crepitus
Among the many auscultatory signs, it is very important to distinguish between crepitation – a peculiar sound phenomenon similar to crunching or crackling observed during auscultation.
Crepitation occurs in the alveoli, most often when there is a small amount of inflammatory exudate in them. At the height of inspiration, many alveoli come apart, the sound of which is perceived as crepitus; it resembles a slight crackling sound, usually compared to the sound that occurs when rubbing hair between your fingers near the ear. Listen for crepitus only at the height of inspiration and regardless of the cough impulse.
- Crepitation, first of all, is an important sign of the initial and final stages of pneumonia (crepitatio indux and crepitatio redux), when the alveoli are partially free, air can enter them and cause them to come apart at the height of inspiration. At the height of pneumonia, when the alveoli are completely filled with fibrinous exudate (stage of hepatization), crepitus, like vesicular breathing, naturally is not heard.
- Sometimes crepitus is difficult to distinguish from fine-bubble ringing wheezing, which, as stated above, has a completely different mechanism. In order to distinguish these sound phenomena, which indicate different pathological processes in the lungs, it should be borne in mind that wheezing is heard during inhalation and exhalation, and crepitus is only heard at the height of inspiration; After coughing, wheezing may temporarily disappear. You should avoid using the unfortunately still widespread incorrect term “crepitating wheezing,” which confuses the phenomena of crepitation and wheezing, which are completely different in origin and place of occurrence.
An audible alveolar phenomenon, very reminiscent of crepitus, can also occur with deep inspiration and with some changes in the alveoli that are not of a classic pneumonic nature. It is observed in the so-called fibrosing alveolitis. In this case, the sound phenomenon persists for a long time (for several weeks, months and years) and is accompanied by other signs of diffuse pulmonary fibrosis (restrictive respiratory failure).