Investigation of the Effects of Respiratory Muscle Training Combined With Otago Exercises in Elderly Patients Undergoing Coronary Artery Bypass Graft Surgery

Coronary artery bypass graft (CABG) surgery aims to revascularize the myocardium by bypassing one or more coronary arteries narrowed or occluded due to atherosclerosis. Procedures such as sternotomy, cardiopulmonary bypass, general anesthesia, and pleural drain placement can lead to postoperative complications including hypersecretion, hypoxemia, decreased pulmonary compliance, reduced exercise capacity, and impaired lung function. These complications may cause prolonged immobilization and additional pulmonary issues. Moreover, protein catabolism after cardiovascular surgery leads to muscle protein loss, which is exacerbated by immobilization, slowing protein synthesis and accelerating muscle fiber breakdown and cell death, thereby contributing to muscle loss progression. Postural balance also decreases following CABG, potentially leading to reduced functional activities, increased fall risk, morbidity, and mortality. CABG negatively impacts patients' quality of life and causes functional limitations. Anxiety about disease recurrence and fear of death after discharge contribute to psychological stress for patients and relatives, further impairing recovery.

Frailty is closely associated with cardiopulmonary diseases and is common after CABG surgery. A study evaluating 180 bypass patients with an average age of approximately 69 years found that 23.3% were frail. High frailty scores post-CABG correlate with adverse outcomes such as prolonged hospital stays and rehospitalization within 30 days.

Inspiratory muscle training (IMT) is a method designed to strengthen inspiratory muscles by providing airway resistance during breathing. Effective IMT requires appropriate intensity, duration, and frequency. Training at or above 30% of maximal inspiratory pressure (MIP) for 20-30 minutes daily, five days a week, over 5-12 weeks produces structural changes in respiratory muscles.

Previous studies demonstrated that IMT improves inspiratory muscle strength, functional capacity, psychosocial status, and quality of life in patients undergoing CABG surgery. Additionally, moderate to high-intensity IMT combined with aerobic and strengthening exercises during cardiac rehabilitation increases exercise capacity, inspiratory muscle strength, and quality of life more than sham IMT combined with similar exercises.

High-intensity intermittent IMT has recently shown beneficial results in cardiovascular and pulmonary diseases. In heart failure patients, high-intensity intermittent IMT performed in cycles of loading and rest improved dyspnea, frailty, fatigue, inspiratory muscle strength, respiratory muscle endurance, exercise capacity, and quality of life, compared to sham IMT. Similar positive effects were observed in patients with bronchiectasis and elderly individuals undergoing home-based IMT, with improvements in inspiratory muscle function, balance, and physical performance.

IMT has demonstrated effectiveness in reducing dyspnea, improving respiratory muscle strength, pulmonary function, functional capacity, daily living activities, and quality of life in patients with chronic obstructive pulmonary disease, chronic kidney disease, chronic heart failure, and in healthy populations. It also enhances postural stability due to the diaphragm's mechanical role in lumbar stabilization.

The Otago exercise program, developed in New Zealand to prevent falls, is a home-based training protocol including warm-up, strengthening, balance, and walking exercises. Performed three times weekly with progressively increasing intensity, it improves lower extremity muscle strength, balance, and mobility in elderly individuals.

Few studies have investigated the combination of IMT and the Otago exercise program. Recent research in healthy adults and diabetic patients indicates that combined training improves balance, inspiratory muscle function, mobility, respiratory function, muscle strength, and endurance more than either intervention alone.

This prospective, randomized, controlled, single-blind study will evaluate the effects of the Otago exercise program combined with high-intensity IMT on elderly patients undergoing CABG surgery. The study will be conducted at Istanbul University-Cerrahpaşa Cardiology Institute, Department of Cardiovascular Surgery.

• Maximum expiratory pressure [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Forced vital capacity (FVC) massessment [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Assessment of functional capacity [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Evaluation of muscle strength [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Assessment of functional mobility [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Balance assessment [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Assessment of anxiety and depression level [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Frailty assessment [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Assessment of quality of life [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Forced expiratory volume in one second (FEV1) assessment [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• FEV1/FVC ratio [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]
• Forced expiratory flow 25-75% (FEF25-75) assessment [Time frame: The baseline assessment will be conducted at 2 weeks post-surgery. Following the completion of the 8-week intervention protocol, the final assessment will be performed at 10 weeks post-surgery.]