**2.3 Different etiologies, types, and characteristics of pathological respiratory patterns**

If structural and/or functional changes occur, then adequate air transport to and from the lungs can be compromised. There are different etiologies, types, and pathological respiratory patterns in which wearable systems may assist in the characterization of movement patterns [1]. This capacity helps in the analysis of the health condition of patients, providing important additional information.

Thoracic mobility is related to the integrity of the nerve pathways and respiratory muscles [13]. In clinical practice, thoracic and abdominal amplitude measurements during respiratory movement may provide information on changes in the respiratory system or eventual diseases [17]. Some paradoxical movements may occur when patients present weakness, muscle paralysis, or chronic obstructive pulmonary disease (COPD), with pulmonary hyperinflation, among other commitments [18]. Another example is Cheyne-Stokes breathing, which is a type of central sleep apnea with an unstable breathing pattern throughout the night. It can cause changes in respiratory frequency and depth of patients with congestive heart failure [19].

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*Breathing Monitoring and Pattern Recognition with Wearable Sensors*

**2.4 Pulmonary auscultation: sounds in healthy and diseased lungs**

tion allows obtaining significant data from lung sounds. Normal pulmonary sounds are classified into:

than expiration, with a pause between events [21].

similar, with no pause between events [22].

with no pause between events [21].

titious noises, are classified into:

expiration [21].

respiratory cycle [22].

breathing [21].

Other impairments may cause changes in the thoracic and abdominal mobility relation such as dyspnea, orthopnea, alternate breathing, forced expiration, etc. Wearable systems capable of monitoring the contribution of different muscles and changes in mobility patterns can help monitor the evolution of the respiratory

Lung sounds occur because of air turbulence in the larger airways [15, 20]. They are the results of pulmonary vibrations and the respective airways transmitted to the thoracic wall. Sounds that occur during natural breathing differ depending on where they are acquired as well as the moment of the ventilatory cycle [20]. So, controlling where to place wearable devices and their sampling frequency and dura-

• Tracheal sound: it is audible in the region of the trachea from cervical to sternal height, having an intense and tubular sound. Inspiration is slightly shorter

• Bronchial sound: it is audible in the region of the bronchi, at the height of the sternal manubrium, having less intensity than the tracheal sound. The duration of inspiration and expiration is similar, with a pause between events [22].

• Bronchovesicular sound: it is audible in the first and second intercostal spaces and between the scapulae. The duration of inspiration and expiration is

• Vesicular murmur: it is audible in the peripheral regions of the lungs, having less intensity than the bronchial sound. Inspiration is longer than expiration,

The anatomical structures may influence the sound heard during normal

• Wheezing: it occurs with the oscillations of the bronchial pathways [22].

• Rhonchus: similar to snoring, it can be heard during inspiration and/or

• Crackles: they are discontinuous sounds, presented in a short and explosive manner, usually classified considering their duration and loudness, during the

There are other sounds and more details about each of them, and wearable systems contribute to distinguishing the different sounds in clinical practice.

The concepts presented in this section are very important for understanding the respiratory system in healthy and unhealthy conditions. Depending on the event one aims to observe, this information helps to identify the best location for sensor placement. It also contributes to a better interpretation of the respiratory signals obtained.

Pathological changes in the lungs directly affect the perception of lung sounds from the airways to the thoracic surface. Abnormal lung sounds, also called adven-

*DOI: http://dx.doi.org/10.5772/intechopen.85460*

functional condition of a person.
