Lung wheezing

Wheezing (rhonchi) - respiratory noises caused by narrowing of the respiratory tract or the presence of pathological contents in them. Wheezing occurs mainly in the bronchi, less often - in cavities with bronchial communication (cavern, 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.

1. The presence in the lumen of the bronchi of more or less dense masses set in motion by the air stream.
2. Changes in the condition of the bronchial wall, and consequently, 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 occurrence of wheezing in bronchitis, broncho-obstructive syndrome and bronchial asthma.

René Laennec described the phenomenon he called wheezing as follows: "In the absence of a more specific term, I have used this word, designating as wheezing all the noises produced during breathing by the passage of air through all the liquids that may be present in the bronchi or lung tissue. These noises also accompany coughing, when it is present, but it is always more convenient to examine them during 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.

[ 1 ]

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, have a whistling and buzzing character. They are always audible throughout the entire inhalation and exhalation. The pitch of wheezing can be used to judge the level and degree of narrowing of the bronchi. A higher timbre of sound (rhonchi sibilantes) is characteristic of obstruction of small bronchi, a lower one (rhonchi sonori) is noted with damage to the bronchi of medium and large calibers. At the same time, the difference in the timbre of wheezing when involving bronchi of different calibers is explained by the different degree of resistance to the air flow 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. The detection of unilateral dry wheezing over a certain area, especially in the upper segments, usually indicates the presence of a cavity in the lung (most often a cavern).

[ 2 ], [ 3 ]

Moist rales in the lungs

When less dense masses (liquid sputum, blood, edematous fluid) accumulate in the bronchi, and when the air stream passing through them produces a characteristic sound effect, traditionally compared to the sound of bursting bubbles when blowing air through a tube lowered into a vessel with water, moist wheezing is formed.

The nature of wet rales depends on the caliber of the bronchi where they occur. There are small-bubble, medium-bubble and large-bubble rales, which occur in small, medium and large-caliber bronchi, respectively. When bronchi of different calibers are involved in the process, wheezing of different calibers is detected.

Most often, wet wheezing is observed in chronic bronchitis, as well as in the resolution stage of an asthma attack; in this case, small-bubble and medium-bubble wheezing are not sonorous, since their sonority decreases when passing through a heterogeneous environment.

Of great importance is the detection of 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 the compaction (infiltration) of the lung tissue. This is especially important for identifying foci of infiltration in the apex of the lungs (for example, in tuberculosis) and in the lower parts of the lungs (for example, foci of pneumonia against the background of blood stagnation due to heart failure).

Voiced medium-bubble and large-bubble rales are detected less frequently. Their occurrence indicates the presence of partially fluid-filled cavities in the lungs (cavern, abscess) or large bronchiectasis communicating with the respiratory tract. Their asymmetric localization in the area of the apex or lower lobes of the lungs is characteristic of these pathological conditions, while symmetrical wheezing indicates blood stagnation in the pulmonary vessels and the entry of the liquid part of the blood into the alveoli.

In case of pulmonary edema, moist, large-bubble wheezing can be heard from a distance.

Crepitus

Among the many auscultatory signs, it is very important to distinguish crepitation - a peculiar sound phenomenon, similar to crunching or crackling, observed during auscultation.

Crepitation occurs in the alveoli, most often when they contain a small amount of inflammatory exudate. At the height of inspiration, many alveoli separate, the sound of which is perceived as crepitation; it resembles a light crackling, usually compared to the sound of rubbing hair between the fingers near the ear. Crepitation is heard only at the height of inspiration and regardless of the cough impulse.

• Crepitation is primarily 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 at the height of inspiration cause them to dehisce. At the height of pneumonia, when the alveoli are completely filled with fibrinous exudate (the stage of hepatization), crepitation, like vesicular breathing, is naturally not heard.
• Sometimes crepitus is difficult to distinguish from fine-bubble sonorous rales, which, as noted above, have 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 only at the height of inhalation; after coughing, wheezing may temporarily disappear. It is necessary to avoid using the unfortunately still widespread incorrect term "crepitating wheezing", which confuses crepitus and wheezing, which are completely different in origin and place of occurrence.

The alveolar sound phenomenon, very similar to crepitus, can also occur with deep inspiration and with some changes in the alveoli that are not of a classical 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).

[ 4 ], [ 5 ], [ 6 ], [ 7 ]