From the Guidelines
Wheezing and rales/crackles are distinct abnormal breath sounds that indicate different underlying pathologies, with wheezing being a high-pitched sound associated with bronchial obstruction and rales/crackles being brief, discontinuous sounds associated with alveolar or lower airway disease. The distinction between wheezing and rales/crackles is crucial in clinical practice, as it can guide diagnosis and treatment decisions [@\1@]. Wheezing is typically heard during expiration and sometimes inspiration, and is characteristic of conditions involving bronchial obstruction or narrowing, such as asthma, COPD, bronchitis, or foreign body aspiration. On the other hand, rales/crackles are brief, discontinuous popping sounds created when previously collapsed or fluid-filled alveoli suddenly open during inspiration, and are commonly associated with conditions like pneumonia, pulmonary edema, pulmonary fibrosis, and bronchiectasis [@\1@]. The key distinction lies in their acoustic properties and timing: wheezes are continuous, musical sounds often heard on expiration, while crackles are discontinuous, non-musical sounds typically heard during inspiration. Proper identification of these sounds during auscultation helps clinicians narrow down potential diagnoses and guide appropriate treatment decisions, as illustrated by the American Thoracic Society's clinical practice guidelines for the diagnostic evaluation of infants with recurrent or persistent wheezing [@\1@]. In clinical practice, the management of wheezing and rales/crackles depends on the underlying cause, with some conditions requiring conservative therapy and others requiring more invasive interventions, such as positive airway pressure or surgery [@\1@]. For example, infants with wheezing due to tracheomalacia, bronchomalacia, or tracheobronchomalacia may be managed by observation alone if wheezing is the only abnormality or the associated symptoms are mild, while those with life-threatening airway obstruction or respiratory failure may require more aggressive interventions [@\1@]. Overall, the accurate identification and differentiation of wheezing and rales/crackles is essential for providing high-quality patient care and improving outcomes [@\1@].
From the Research
Wheezing versus Rales/Crackles
- Wheezing is a high-pitched whistling sound produced by airflow through narrowed airways, often associated with asthma and chronic obstructive pulmonary disease (COPD) 1.
- Rales, also known as crackles, are abnormal sounds heard during auscultation, indicating the presence of fluid or inflammation in the lungs.
- The key difference between wheezing and rales/crackles lies in their underlying causes and the sounds they produce: wheezing is typically a high-pitched sound associated with airway narrowing, while rales/crackles are lower-pitched sounds associated with fluid or inflammation in the lungs.
Diagnosis and Treatment
- Initial tests for wheezing typically include a chest x-ray and pulmonary function testing with bronchodilator challenge 1.
- Bronchodilators can produce modest short-term improvement in clinical features of mild or moderately severe bronchiolitis, particularly in children with first-time wheezing 2.
- Advanced imaging to evaluate for malignancy should be considered in patients older than 40 years with a significant history of tobacco use and new-onset wheezing 1.
- A trial of short-acting beta agonists can be considered while awaiting formal evaluation 1.
Bronchodilator Therapy
- Nebulized bronchodilators are widely regarded as the optimal treatment for maintenance therapy in patients with severe COPD 3.
- The effectiveness of bronchodilator therapy can be assessed through physiological, functional, and quality of life-related measurements 3.
- Short-term trials of bronchodilator drugs can be used to assess patients with stable COPD, but the equivalence of the FEV1 response to beta-agonists and anticholinergic drugs is uncertain 4.
- The prehospital use of aerosolized bronchodilators is feasible and most useful in patients with mild or moderately severe symptoms 5.