The Effect of Inspiratory Muscle Training on Breathing Pattern and Functionality in Patients With Chronic Heart Failure.

Diaphragmatic thickness measured by ultrasound is a non-invasive, widely used method to assess diaphragm structure in patients with chronic heart failure. Thickness is measured between the pleural and peritoneal lines at end-expiration and end-inspiration

Dysfunctional breathing refers to abnormal breathing patterns that are often related to the heart's inability to supply blood effectively, affecting respiratory function. Dysfunctional breathing will be assessed with the Hi-Lo breathing test, an observational clinical test used to assess breathing pattern and diaphragm function. The clinician observes and palpates whether the movement is greater under the upper chest hand (Hi) or lower abdomen hand (Lo).The test is scored as "Yes" if upper chest (apical) breathing predominates and "No" if normal diaphragmatic breathing is present.

Functional ability refers to how well patients can perform daily activities and maintain independence despite their cardiac condition. It will be assessed with the 6-Minute Walk Test (6MWT), a simple and effective tool that evaluates the maximum distance a person can walk in six minutes. The outcome reflects the integrated response of the cardiovascular system mainly, and exercise tolerance.

It is a measure of the strength of inspiratory muscles, primarily the diaphragm. MIP is a reliable and reproducible measure that does not depend on the patient's respiratory flow.

Functional dyspnea will be measured with the Medical Research Council (MRC) Dyspnea scale, a simple grading system to evaluate the functional disability due to dyspnea. The scale ranges from 1 to 5, where 1 indicates breathlessness only with strenuous exercise and 5 indicates breathlessness that prevents leaving the house or occurs when dressing or undressing. Higher scores represent worse functional status (more severe dyspnea).

Quality of life will be evaluated with the Short Form Survey, a questionnaire with 12-items, that measures quality of life in terms of physical and mental health. It generates scores typically ranging from 0 to 100, with higher scores indicating better health status and quality of life.