From the Guidelines
Inspiratory sounds, particularly stridor, are a hallmark sign of exercise-induced laryngeal dysfunction (EILD), which can be differentiated from exercise-induced bronchoconstriction (EIB) by the presence of inspiratory symptoms and stridor during exercise. Inspiratory sounds are the noises heard during the inhalation phase of breathing, and in the context of EILD, they can be abnormal, indicating upper airway obstruction 1. Normal inspiratory sounds are soft, low-pitched, and have a rustling quality when heard over most lung fields. However, in patients with EILD, inspiratory stridor is a key feature, which is a high-pitched sound resulting from upper airway obstruction 1.
Key Features of Inspiratory Sounds in EILD
- Inspiratory stridor is the signature clinical feature suggesting EILD rather than EIB 1
- The onset of breathing difficulties occurs and peaks during exercise with EILD, rather than peaking after exercise with EIB 1
- Inspiratory stridor with throat tightness during maximal exercise resolves within approximately 5 minutes of discontinuation of exercise in patients with EILD 1
- Direct observation of vocal cord adduction by means of laryngoscopy and flattening or truncation of the inspiratory portion of the spirometric flow-volume loop are the hallmarks for diagnosis of EILD 1
Diagnosis and Management
- Diagnosis can be made directly by using continuous laryngoscopy during exercise challenge 1
- Spirometry and laryngoscopy with sound recording can be performed during exercise, detecting minor and major aryepiglottic and vocal cord abnormalities 1
- Medications used to treat asthma, such as b2-agonists, are ineffective to prevent or reverse EILD 1
- Empiric pharmacologic treatment of GERD in juveniles with VCD has been recommended because posterior laryngeal changes associated with GERD are common in these patients 1
From the Research
Inspiratory Sounds
- Inspiratory sounds can be an important indicator of respiratory health, and analyzing these sounds can help in diagnosing obstructive airway disease (OAD) 2.
- A study published in 2009 found that patients with acute dyspnea due to OAD had distinguishing features when studied with a computerized acoustic-based imaging technique, including a lower peak inspiratory to peak expiratory vibration energy values (peak I/E vibration ratio) and a lower inspiratory time to expiratory time (I/E time ratio) compared to patients without OAD and normal controls 2.
- The use of azithromycin in patients with chronic obstructive pulmonary disease (COPD) has been shown to reduce exacerbations and improve lung function, but its effect on inspiratory sounds is not directly addressed in the available studies 3, 4, 5.
- However, a study on azithromycin in treatment of patients with asthma and C. Pneumoniae infection found that treatment with azithromycin significantly improved asthma symptoms and lung function, which may be related to changes in inspiratory sounds 6.
Azithromycin Therapy
- Azithromycin therapy has been shown to be effective in reducing exacerbations of COPD and improving lung function in patients with severe COPD 3, 4, 5.
- The therapy is recommended for use in COPD patients who are at risk for recurrent exacerbations, but concerns about adverse effects have limited its widespread adoption 5.
- The available studies do not provide direct evidence on the effect of azithromycin on inspiratory sounds, but they suggest that the therapy may have a positive impact on respiratory health, which could be related to changes in inspiratory sounds 3, 6, 4, 5.