Crepitation and pleural friction noise are pathologies that occur in the work of the respiratory tract. This article will highlight the differences between these two violations. First, consider what crepitus is.
Crepitation
This phenomenon appears at the height of inspiration in the form of a crackle and resembles the sound obtained by rubbing a small tuft of hair over the ear. The main condition for the formation of crepitus is the accumulation of a viscous secret or fluid in the lumen of the alveoli. In this case, the walls of the alveoli stick together in the exhalation phase, and at the height of inhalation, when the air pressure in the lumen of the bronchi is maximally increased, they come apart with great difficulty. Therefore, crepitus is heard only in the final phase of breathing.
Causes of pathology
Crepitation is observed in the following cases:
- when lung tissue becomes inflamed in the first and third stages of lobar pneumonia;
- with infiltrative pulmonary tuberculosis;
- with congestion occurring during the pulmonary circulation, which resulted in a weakening of the contractile function of the muscle in the left ventricle;
- whenpulmonary infarction.
Crepitus with a decrease in the elasticity of the lung tissue is most often heard at the first deep breath in the lower lateral parts of the lungs in elderly people. Transient crepitus may also occur with compression atelectasis.
Diagnosis of crepitus
The acoustic properties of crepitus can often resemble small bubbling moist rales, which are formed during the accumulation of liquid secretion in the bronchioles or in the smallest bronchi. Therefore, its difference from wheezing is of great importance in terms of diagnosis. The presence of inflammation in the lungs is indicated by persistent crepitus, and the inflammatory process only in the bronchi or congestion in the lungs is indicated by small bubbling rales.
Differential diagnostic signs of crepitus:
- wheezing is heard both on inhalation and exhalation, after coughing they may intensify or disappear;
- crepitus is heard only at the height of inspiration, its strength and character after coughing does not change.
Pleural rub
Under physiological conditions, the parietal or visceral pleura have a smooth surface and constant wet lubrication. Therefore, in the process of breathing, their sliding occurs silently. Pathological conditions of various etiologies lead to the fact that there is a change in the physical properties of the petals and conditions are created that contribute to their stronger friction against each other. As a result, a peculiar additional sound arises,called pleural friction noise.
Reasons
One of the conditions for the appearance of such noises is the unevenness or roughness of the pleura when it is inflamed. These noises appear due to the deposition of fibrin or subsequently inflammation and the subsequent development of scars (connective tissue), adhesions between the sheets. The surface of the pleura sheets becomes uneven when cancerous nodules or tuberculous tubercles are shed on them. There is a friction noise of the pleura and with a sharp dryness of the sheets, due to the rapid loss of a large amount of fluid by the body during severe, uncontrollable diarrhea or massive blood loss.
Diagnosis
A pleural friction rub is heard both on inspiration and on expiration. It differs in volume, strength, place of definition, duration of existence. With a sharp dehydration of the body or at the initial stage of development of dry pleurisy, the noise is more gentle, quiet and resembles in its timbre the sound that occurs when there is friction between pieces of silk fabric. During the period of active treatment of dry pleurisy, it changes its character and the friction noise of the pleura resembles crepitus or small bubbling wheezing, and in some cases the crunch of snow. The friction noise of the pleural sheets becomes coarser with exudative pleurisy. It reminds not only the sound of snow, but also the creak of a leather belt. Usually, such low-frequency vibrations can be determined by palpation.
Duration
Duration may vary. With rheumatism, for example, noise may be observed for a couple of hours, and then an abyssand reappear after a while. With dry pleurisy, which has a tuberculous etiology, pleural friction noise can be heard continuously for several days, and with exudative pleurisy - more than a week. In a number of patients, after they have suffered pleurisy, rough cicatricial changes in the pleura and an uneven surface of the sheets may appear. This can result in noise being heard for many years.
Listening places
Listening places can also be different. It depends on where the focus of inflammation is located. In the lower lateral part of the chest, it is most often detected, since here the lungs move as much as possible during breathing. With rare exceptions, it can be heard in the area where the top of the lungs is located. This happens when the tuberculous process develops in them and inflammation spreads to the pleural sheets. If the inflammatory focus is localized in the pleura, which is in contact with the heart, so-called pleuropericardial murmurs may appear, heard not only during inhalation and exhalation, but also during diastole and systole of the heart. They are heard more distinctly, in contrast to intracardiac murmurs, at the height of a deep breath, when the pleural sheets are more tightly attached to the heart.
So, it's worth summing up, what are the main differences between pleural friction noise and crepitus:
- When crepitus, wheezing disappears for a while or changes its character after coughing, and the friction noise does not change and does not disappear after it.
- If enoughpress hard with a stethoscope on the chest, the pleural friction noise increases, and the nature of wheezing in this case will not change.
- Crepitus is heard only at the height of inspiration, and pleural murmur - in both phases of breathing.
- When oral and nasal breathing is stopped, the pleural noise due to the displacement of the diaphragm and sliding of the sheets can be heard by the ear, and crepitus due to the fact that there is no movement of air through the bronchi, is not audible.
