From the Guidelines
During an asthma exacerbation, the most characteristic breath sound is wheezing, a high-pitched, musical sound produced when air moves through narrowed airways, as noted in guidelines for managing asthma exacerbations 1. The primary breath sounds associated with asthma exacerbation include:
- Wheezing, typically heard during expiration but may also be present during inspiration in more severe cases
- Rhonchi, low-pitched, snoring-like sounds due to secretions in the larger airways
- Prolonged expiratory phase of breathing due to narrowed airways
- Decreased breath sounds or "silent chest" in severe cases, indicating a medical emergency
- Crackles (rales) might occasionally be heard if there is associated inflammation and fluid in the smaller airways
These breath sounds occur because during an asthma exacerbation, bronchospasm, inflammation, and mucus hypersecretion cause airway narrowing, leading to turbulent airflow that produces these characteristic sounds, as described in the management of asthma exacerbations 1. The severity of asthma exacerbations is categorized based on symptoms, signs, and functional lung assessment, including percent predicted FEV1 or PEF, which determines treatment 1. In clinical practice, recognizing these breath sounds is crucial for diagnosing and managing asthma exacerbations effectively, prioritizing morbidity, mortality, and quality of life as outcomes.
From the Research
Breath Sounds in Asthma Exacerbation
- Wheezing is a common breath sound heard in asthma exacerbation, which is caused by airway narrowing and obstruction 2
- Forced expiratory wheeze (FEW) may be an early sign of airway obstruction in patients with bronchial asthma 2
- Bronchial sounds, which are higher than normal breathing sounds, may indicate airway narrowing or airway inflammation 2
- The frequency and intensity of lung sounds increase with airway narrowing, and automated analysis of lung sounds may be used to detect subtle changes in the future 2
Characteristics of Breath Sounds
- The narrower the airways are, the higher the frequency of breathing sounds is 2
- Inspiratory and expiratory wheezes may have the same mechanism of generation as a flutter/flow limitation mechanism, either localized or generalized 2
- Airway wall oscillation and vortex shedding in central airways are the most likely mechanisms of the generation of expiratory wheezes 2
Clinical Assessment
- Assessment of exacerbation severity and lung function is crucial in managing asthma exacerbations 3, 4
- Physical examination parameters, such as breath sounds, are used to classify the severity of asthma exacerbations 3
- The presence of wheezing and other abnormal breath sounds can indicate the severity of airway obstruction and guide treatment decisions 3, 4