Magnetic Stimulation of Diaphragm in Chronic Obstructive Pulmonary Disease

Effect of Repetitive Peripheral Magnetic Stimulation on Diaphragm Muscle Thickness, Symptoms and Functional Capacity in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease characterized by persistent airflow limitation and respiratory symptoms due to airway and/or alveolar deterioration caused by severe exposure to harmful particles or gases and host factors. Exercise intolerance and decreased functional capacity develop as a result of the disorders that occur in COPD.

The aim of this study is to evaluate the effectiveness of repetitive peripheral magnetic stimulation (rPMS), an easy and inexpensive method to increase diaphragm strength as an adjunct to the pulmonary rehabilitation (PR) program applied in COPD, and to investigate the effect of this method on exercise capacity, diaphragm muscle thickness and symptoms.

COPD is a life-threatening public health problem that starts with shortness of breath, continues with exacerbations, and the prognosis gradually worsens. In COPD patients, respiratory functions decrease due to changes in the airways in the advanced stages of the disease; dyspnea, cough, and sputum emerge as three important symptoms. Respiratory function limitations and symptoms caused by the disease also cause physical and psychological disorders such as peripheral muscle weakness, exercise intolerance, decreased quality of life, depression, and anxiety in patients. Diaphragm dysfunction also develops in COPD. In severe COPD, changes occur in the sarcomere length, enzyme activity, and mitochondrial density of diaphragm muscle fibers. Recurrent COPD attacks also negatively affect diaphragm dysfunction. Due to diaphragm dysfunction, patients' exercise tolerance and daily living activities decrease even more after attacks; their quality of life decreases. The aim of treatment and care in COPD is to prevent progression, reduce symptoms, prevent and/or treat recurrent acute attacks, protect respiratory functions in the long term and prevent functional decline, increase exercise capacity, reduce complications and protect and increase quality of life. Since drug therapy alone is insufficient to achieve these goals, rehabilitation practices should also be a part of the treatment in addition to drug therapy.

Oxygen therapy, nutritional support, pulmonary rehabilitation (PR) approaches are also among the supportive and palliative treatment methods. In the last twenty years, the negative effects of systemic symptoms on the functions of patients in COPD patients have accelerated the development and use of PR. The main goals of PR are to reduce symptoms, bring the person's functional and emotional status to the best possible level, increase participation in daily life and quality of life, and reduce health-related expenses by reversing or stabilizing the systemic effects of the disease. PR has been shown to be the most effective non-pharmacological intervention to improve health status in COPD patients. The main component of PR programs is exercise; which includes aerobic exercise, strengthening exercises, inspiratory muscle training, controlled breathing techniques, bronchial hygiene techniques, stretching exercises, relaxation exercises, as well as water exercises, pilates and yoga programs. There are also daily life activity practices and assistive device training exercises.

Considering the weakness of peripheral muscle and diaphragm muscle strength in COPD patients, alternative strengthening methods for these muscles are important. rPMS is a physical therapy method based on the interaction between a high-intensity electromagnetic field and the human body. The electromagnetic field is generated by a coil placed in the applicator. Depending on the frequency of stimulation and the intensity of the electromagnetic field, it has analgesic, muscle relaxant or muscle strengthening effects. The rPMS method, which is one of the alternative treatment methods that strengthens the diaphragm, does not require direct contact with the skin. Since it can be applied over clothes, the patient does not need to undress or prepare the skin. It is not painful like other invasive methods, so the patient's compliance will be higher and the possibility of abandoning the treatment is less. The rPMS application is fast and easy to use, because there is no need to connect a stimulating electrode to the patient.

In this study, it is planned to investigate the hypothesis that adding rPMS of the diaphragm to the PR program in individuals with COPD would lead to more improvement in exercise capacity, diaphragm muscle thickness, and consequently, symptoms.

In line with this hypothesis, the aim of the study was to evaluate the effectiveness of repetitive peripheral magnetic stimulation (rPMS) to increase diaphragm strength in addition to the PR program applied in COPD, and to investigate the effect of this method on exercise capacity, diaphragm muscle thickness and symptoms.

This is a prospective, randomized, sham-controlled, single-blind, experimental study. Patients who admitt to Ankara University Medical Faculty Hospital Physical Medicine and Rehabilitation Clinic for PR and have stable COPD diagnosis will be invited to the study. This study will be conducted within the scope of good clinical practices and written informed consent forms will be obtained from all patients. The sociodemographic information, smoking history, duration of COPD, presence of co-morbidities, regularly used medications, and other medical history of the patients will be recorded. Patients will be randomized into two groups. Both groups will receive 24 sessions of standard PR programs. Intervention group will also receive repetitive peripheral magnetic stimulation (rPMS) to strengthen the diaphragm muscle. Patients will be evaluated at baseline and at the end of the program. The assessments will include cardiopulmonary exercise test (CPET) for dynamic respiratory functions and VO2max and six-minute walk test to determine functional exercise capacity, Saint George Respiratory Questionnaire (SGRQ) for health specific quality of life, Transitional Dyspnea Index (TDI) measuring changes in shortness of breath, Modified Medical Research Council (mMRC) Dyspnea Scale and diaphragm muscle thickness measurement with ultrasonography.

Inclusion Criteria:

1. Having been diagnosed with COPD at least 6 months ago
2. Being over 18 years of age
3. Having the cognitive ability to understand the questions and fill out the questionnaires
4. Agreeing to participate in the study

Exclusion Criteria:

1. Presence of chest wall deformity
2. Presence of pacemaker/defibrillator
3. Pregnancy
4. Presence of acute respiratory tract infection and/or pneumonia
5. Suspicion of underlying hemidiaphragmatic paresis (defined as elevation of one hemidiaphragm >2.5 cm compared to the other on chest radiography)
6. Known history of inflammatory rheumatologic or neuromuscular disease that may affect the mechanics of the diaphragm (cerebrovascular accident, spinal cord injury, epilepsy, peripheral neuropathy, and muscle diseases, etc.)
7. Suspected paraneoplastic or myopathic syndromes and/or use of medications known to alter muscle structure and/or function, including oral corticosteroids
8. History of recent thoracic and/or abdominal surgery
9. History of COPD exacerbation within the last 4 weeks
10. COPD disease is accompanied by bronchial asthma, interstitial lung diseases, lung neoplasia, metabolic diseases (diabetes mellitus, uremia and liver failure)
11. Body mass index greater than 40
12. Presence of contraindications for exercise program (uncontrolled atrial/ventricular arrhythmia, resting systolic blood pressure ≥ 200 mm Hg or diastolic blood pressure ≥ 110 mm Hg, severe aortic stenosis, recent history of embolism, decompensated heart failure, cardiac ischemic event within the last four weeks)
13. Presence of systemic disease and/or musculoskeletal disease that may prevent exercise