Auscultation topography
According to the principle of symmetry, the physician moves the stethoscope sequentially across paired points on the chest to detect local changes in sound transmission.
- On the anterior surface, auscultation covers the lung apices (above the clavicles), the subclavian regions, and the lower sections along the midclavicular and anterior axillary lines.
- On the posterior surface, auscultation encompasses the supraspinous fossae (projection of the upper lobes), the interscapular space, and the subscapular regions where the lung bases are projected.
Vesicular breath sounds
This is the primary breath sound normally heard over the vast majority of the pulmonary parenchyma. The term was introduced by René Laënnec.
Mechanism of formation: The sound is generated during inspiration when air rapidly fills the alveoli. Their elastic walls quickly expand and vibrate. The vibrations of millions of alveoli merge to create a soft, gentle, and uniform sound resembling a quiet breeze.
Phase characteristics:
- Inspiration (inspirium) is heard throughout (long phase).
- Expiration (expirium) is either completely inaudible or captured only at the very beginning (short phase).
The presence of vesicular breath sounds confirms that this lung segment is ventilated and the feeding bronchi are patent. Furthermore, the quality of sound transmission directly depends on the homogeneity of the lung tissue: the more homogeneous it is, the better the sound resonates.
Bronchial breath sounds
Mechanism of formation: This type of breath sound is generated when an air jet passes at high velocity through anatomical constrictions, such as the vocal cords or the upper trachea. Harsh sound vibrations lacking softness are produced. Laënnec described this phenomenon as the sound of air passing 'into an empty and wide space'.
Phase characteristics:
- Inspiration is short and harsh.
- Expiration is prolonged, loud, and predominates over inspiration.
Normal localization: Because heterogeneous lung tissue dampens coarse oscillations, physiological bronchial breathing is heard only over the projection of the trachea (in the jugular notch) and in the interscapular region at the level of the 7th cervical vertebra (especially in asthenic individuals). The appearance of such breathing in other zones indicates the formation of pathological cavities or lung tissue consolidation.
Changes in vesicular breathing
In clinical practice, three main variants of changes in normal breathing are distinguished: intensification, weakening, and the acquisition of a harsh tone.
- Enhanced breathing: The amplitude and volume of the sound increase. It occurs with significant physical exertion or hyperthyroidism.
- Harsh breathing: Inspiration and expiration become equal in loudness, and the timbre acquires a roughness. This is a consequence of uneven thickening of the bronchial walls during exudative inflammation and bronchospasm. It is characteristic of bronchitis (an elongated harsh expiration is particularly prominent).
- Weakened breathing: Graphically, the phases become shorter and quieter. It occurs for several reasons:
- Impaired sound transmission (a barrier of fluid in hydrothorax or gas in pneumothorax).
- Alteration of alveolar structure (inflammation, fibrosis).
- Loss of tissue elasticity (emphysema).
- Reduced respiratory excursion (obesity, adhesions, pain syndrome in rib fractures or pleurisy).
- Atelectasis (obstructive due to bronchial occlusion by a tumor, or compression due to lung compression).
An extreme and dangerous degree of weakening is "silent lung"—the complete absence of respiratory sounds. It develops in status asthmaticus due to generalized bronchospasm and obstruction of small bronchi by secretion, requiring immediate mechanical restoration of airway patency (e.g., bronchoscopy).
Adventitious breath sounds
In addition to basic sounds, additional sound phenomena may be auscultated in pathology:
- Dry rales: Divided into low (bass, buzzing) and high (discant, wheezing). High rales often indicate bronchial asthma or laryngeal stenosis.
- Moist rales: Divided by the caliber of the formed bubbles into large-, medium-, and fine-bubbling. Fine-bubbling rales, in turn, can be sonorous (consonating—a sign of lung tissue consolidation around the affected bronchus) and non-sonorous (non-consonating).
Briefly: answers to topical questions
In which pathological conditions does harsh breathing appear?
Harsh vesicular breathing is described in conditions associated with uneven thickening of the bronchial walls; it is especially pronounced in exudative inflammation and bronchospasm. According to sources, it occurs in:
- bronchitis;
- bronchial obstruction syndrome;
- bronchiectasis — against the background of harsh breathing, sonorous fine-bubbling moist rales are auscultated;
- interstitial (atypical) pneumonia;
- focal pneumonia with a superficial location of the focus;
- hemorrhagic fever with renal syndrome.
Which sound phenomena belong to additional (adventitious) respiratory sounds?
Additional respiratory sounds include pathological sound phenomena, each of which has a strictly defined source and mechanism of occurrence. Main types:
- Rales (rhonchi) — formed in the airways.
- Crepitation (crepitatio) — is exclusively an alveolar phenomenon.
- Pleural friction rub — occurs when the pleural leaves are affected.
- Pleuropericardial rub.
What is the pathogenetic difference between sonorous (consonating) and non-sonorous moist rales?
The pathogenetic difference lies in the conditions of sound conduction by the surrounding lung tissue.
| Characteristic | Sonorous moist rales | Non-sonorous moist rales |
|---|---|---|
| Mechanism | Consolidated tissue around the bronchus conducts sound better from the bronchi to the periphery | Loudness decreases due to sound passing through a "heterogeneous" air medium, in emphysema or absence of tissue consolidation |
| Clinical significance | Indicate peribronchial inflammation and lung tissue consolidation; fine-bubbling sonorous rales indicate a focus of infiltration around small bronchi | More common in chronic bronchitis or during the resolution stage of a bronchial asthma attack. |
In which diseases does pathological bronchial breathing appear outside physiological zones?
Pathological bronchial breathing occurs with lung tissue consolidation or the presence of cavities, provided the patency of the ventilating bronchus is preserved. Main etiological factors:
- Infiltrative processes: lobar pneumonia, pulmonary tuberculosis, pulmonary thromboembolic infarction.
- Atelectasis: compression atelectasis, initial stages of obstructive atelectasis.
- Cavitary formations: cavity, emptied abscess, large "dry" bronchiectasis (provided there is communication with the bronchus).
How does crepitation differ from fine-bubbling moist rales?
Crepitation and fine-bubbling rales have different formation mechanisms and differ in auscultatory signs.
| Sign | Crepitation | Moist fine-bubbling rales |
|---|---|---|
| Localization of formation | Alveoli | Bronchi of various calibers |
| Respiratory phases | Auscultated only at the height of inspiration | Heard on both inspiration and expiration |
| Effect of coughing | Stable, does not change after coughing | May change in timbre, quantity, or temporarily disappear |
Normally, vesicular breathing can be compared to the sound of the letter "F" (long inspiration, short expiration), and bronchial to the sound of "H" (coarse sound, long and loud expiration).
Class and exam questions
Why is expiration during normal vesicular breathing barely audible?
The sound of vesicular breathing is born at the moment of expansion of the elastic walls of the alveoli on inspiration. On expiration, the tension of the walls quickly drops, so sound vibrations are caught only at the very beginning of the expiration phase.
Does bronchial breathing always indicate pathology?
No, it is normal if it is auscultated over the larynx, trachea (jugular notch), and in the interscapular space. At any other points, its presence indicates a pathological process.
What is harsh breathing and in which diseases does it occur?
This is a variant of vesicular breathing in which inspiration and expiration are equal in loudness, and the timbre becomes harsh due to uneven thickening of the bronchial walls. It is most commonly auscultated in bronchitis.
What is the danger of the "silent lung" syndrome?
This is a critical condition in which, due to total bronchospasm and viscous sputum, air completely stops flowing into the alveoli. Respiratory sounds disappear, conservative therapy often fails, and emergency mechanical clearance of the bronchi is required.
What else to study on this topic
- Mechanisms of moist and dry rales formation
- Differences between consonant and non-consonant fine moist rales
- Pathogenesis of obturation and compression atelectasis
- Graphical recording of respiratory sounds (phonopulmonography)
- Impact of asthenic chest structure on the auscultatory pattern
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