Comparison of Respiratory Muscle Activations During Dyspnea Reduction Positions in Individuals

Chronic obstructive pulmonary disease is a common, preventable and treatable disease characterized by persistent respiratory symptoms and airway limitation due to airway and/or alveolar abnormality, which is affected by many factors that cause abnormal lung development resulting from exposure to harmful gases or particles. Chronic obstructive pulmonary disease is known as the fourth most common cause of death in the world and is expected to rise to third place by the end of 2020. Physiopathological changes such as airflow limitation, bronchial fibrosis, increased airway resistance, ciliary dysfunction, gas exchange abnormalities and air trapping occur in chronic obstructive pulmonary disease. While smoking is the most common risk factor in chronic obstructive pulmonary disease; Occupational dust and chemicals, air pollution, lung growth and development, genetic predisposition such as age and gender, and exposure to environmental effects. Symptoms such as shortness of breath (dyspnea), cough, and sputum are common in chronic obstructive pulmonary disease.

Chronic and progressive dyspnea is the most characteristic symptom of chronic obstructive pulmonary disease. About 30% of individuals with chronic obstructive pulmonary disease have a productive cough. These symptoms can vary from day to day and may precede airflow limitation for years. Significant airflow limitation may also be present without chronic dyspnea, cough, and sputum production. Although chronic obstructive pulmonary disease is defined based on air restriction, individuals with chronic obstructive pulmonary disease usually make the decision to seek treatment based on the effect of symptoms on functional status. Dyspnea, which is the main symptom of chronic obstructive pulmonary disease, is the main cause of disability and anxiety associated with the disease. Typical chronic obstructive pulmonary disease patients define dyspnea as a feeling of increased breathing effort, heaviness in the chest, and air hunger.

Today, it has been shown that there are many underlying causes of dyspnea. In chronic obstructive pulmonary disease patients, minute ventilation and dead space ventilation due to increased workload increase respiratory motor output in association with an increase in carbon dioxide production. As a result, individuals feel short of breath. Simple mechanical distention of the airways during exhalation, which is defined as dynamic airway compression, is another cause of dyspnea in patients with chronic obstructive pulmonary disease. Different positions and breathing patterns affect the perception of dyspnea in individuals with chronic obstructive pulmonary disease. In current studies, individuals with chronic obstructive pulmonary disease have an increased perception of shortness of breath in the supine position (orthopnea); It was observed that the perception of shortness of breath decreased in pursed lib (pursed lip) breathing and dyspnea reduction positions. Therefore, pursed lip breathing and breathlessness reduction positions are frequently used in the treatment of individuals with chronic obstructive pulmonary disease. Leaning forward, comfortable sitting, leaning forward, standing with the back leaning, high side lying are the most commonly used positions to reduce dyspnea.

It has been shown that the forward bending position, one of the dyspnea-reducing positions, improves the length-tension relationship and function of the diaphragm muscle, decreases the activity of the sternocleidomastoideus, scalene muscles, improves thoracoabdominal movement, and helps to reduce shortness of breath. Pursed-lip breathing, on the other hand, increases tidal volume, leading to increased rib cage movement and accessory muscle recruitment during inspiration and expiration.

Compared to healthy individuals, individuals with chronic obstructive pulmonary disease have an increased electromyographic activation of respiratory muscles. In chronic obstructive pulmonary disease patients, there is an increase in respiratory muscle activation and shortness of breath due to the imbalance between the workload and capacity of the respiratory muscles. In current studies, it has been observed that the severity of dyspnea perception and respiratory muscle activations are related.

There are studies in the literature showing that electromyographic activations of respiratory muscles increase in individuals with chronic obstructive pulmonary disease and that the severity of the perceived shortness of breath is associated with muscle activation. However, no study has been found comparing respiratory muscle activations during pursed lip breathing and normal breathing in dyspnea reduction positions and supine position used in the treatment and management of chronic obstructive pulmonary disease. The aim of this study is to evaluate the effects of different dyspnea reduction positions on respiratory muscle activations separately, to compare respiratory muscle activation during normal breathing, respiratory control and pursed lip breathing during these different positions, and to classify muscle activations according to the severity of chronic obstructive pulmonary disease.