In clinical practice, lung sounds are most commonly assessed with no strict control over air flow, 1 because patients are simply asked to breathe deeply with an open mouth. One concern when using lung auscultation as a screening tool is the influence of air flow on respiratory acoustics. 1 Lung sounds may thus be useful screening markers for lung diseases in the general population. 1 Both normal and adventitious lung sounds are directly related to the movement of air, changes within lung morphology, and the presence of secretions, 1, 3 and they have been used as clues for diagnosing lung diseases. 2 The presence of adventitious lung sounds often indicates a pulmonary disorder, although they can also be present in healthy people. 2 Adventitious lung sounds are additional sounds superimposed on normal lung sounds, which can be continuous with a musical character (ie, wheezes), or discontinuous and explosive (ie, crackles). 2 Normal lung sounds are generated by the air flow in the respiratory tract and are characterized by broad-spectrum noise. Lung sounds fall into 2 main categories, normal and adventitious sounds. These advantages of lung auscultation are especially important in primary care settings and in resource-constrained settings, where technologies for diagnostic tests, such as radiography and spirometry, are not available. Lung auscultation is a simple and noninvasive way to assess the function of the respiratory system, 1 and it does not require special resources beyond a stethoscope.
During spontaneous breathing, increased mean intensity and median frequency during expiration were associated with an increased reporting of heart/lung diseases ( P =.
Dyspnea was more frequently reported when expiratory wheezes were present, but this association was only statistically significant during standardized breathing ( P =. The mean intensity and median frequency of normal lung sounds were significantly higher during standardized breathing than during spontaneous breathing, both at inspiration (23.1 dB vs 20.1 dB and 391.6 Hz vs 367.3 Hz) and expiration (20 dB vs17.6 dB and 376.3 Hz vs 355 Hz).
Nine subjects were identified with both methods (kappa = 0.32). Expiratory wheezes were heard in 18 subjects (15.5%) during spontaneous breathing and in 23 subjects during standardized breathing (19.8%). Only 5 subjects were identified with both methods (kappa = 0.13). RESULTS: Inspiratory crackles were heard in 19 subjects (16.4%) during spontaneous breathing and in 18 subjects during standardized breathing (15.5%).
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