From the Guidelines
Expiratory Hum Definition
An expiratory hum is not directly defined in the provided evidence, however, a related concept, the forced expiratory technique (FET), also known as huffing, is described as a maneuver that consists of one or two forced expirations without closure of the glottis starting from mid-lung to low lung volume, followed by relaxed breathing 1.
Characteristics of FET
This technique is used as an alternative to coughing in patients with chronic airway disease, such as COPD, CF, and bronchiectasis, to minimize airway collapse during coughing and improve secretion clearance 1. The intrapulmonary pressures during FET are lower than those during coughing, which may lead to less airway compression and better sputum clearance 1.
Effectiveness of FET
Studies have shown that huffing is as effective as directed cough in moving secretions proximally from all regions of the lung in patients with COPD 1. Additionally, huffing with postural drainage or positive expiratory pressure (PEP) improved sputum clearance in patients with CF compared to no treatment 1.
Clinical Application
While the evidence does not directly address the expiratory hum, the description of the forced expiratory technique (FET) or huffing provides insight into a related respiratory maneuver used to enhance secretion clearance in patients with obstructive airway diseases 1.
From the Research
Definition of Expiratory Hum
There is no direct evidence in the provided studies to define an expiratory hum.
Related Concepts
- Wheezes are defined as high-pitched, continuous, adventitious lung sounds [ 2, 3 ]
- Wheezes are produced by oscillation of opposing airway walls whose lumen is narrowed 3
- Wheezes can be heard in several diseases, not only asthma, and are usual clinical signs in patients with obstructive airway diseases 2
Adventitious Lung Sounds
- Wheezing is the most widely reported adventitious lung sound in the English language 4
- Adventitious lung sounds, including wheezes, can be used to assess airway obstruction 2, 4
Analysis of Wheezes
- Computer-based analyses of wheeze signals have been extensively used for parametric analysis, spectral analysis, identification of airway obstruction, feature extraction, and diseases or pathology classification 5
- Wheeze sound analysis using computer-based techniques can be used for the identification of disease severity level or pathology 5