Effect of Synchronized Transcutaneous Electrical Diaphragm Stimulation Using Surged Faradic Current Combined With Inspiratory Muscle Training on Diaphragm Function and Clinical Outcomes in Patients With COPD

Ethical clearance was obtained from the Institutional Ethics Committee before commencement of the study. A total of 54 CKD patients were screened, of whom 42 participants fulfilling the eligibility criteria were included in the study. Written informed consent was obtained from all participants. Baseline assessment was performed using Pulmonary Function Tests (FEV₁, FVC and FEV₁/FVC ratio), 6-Minute Walk Test (6MWD, VO₂max) and Daily Fatigue Impact Scale (D-FIS).

The 42 participants were randomly allocated into two equal groups of 21 participants each.

Group A - Renal Rehabilitation :

Participants received a structured renal rehabilitation programme consisting of aerobic training, resistance training and inspiratory muscle training for 3 days per week for 12 weeks.

Each session started with 5-10 minutes of warm-up, followed by the training programme and ended with 5-10 minutes of cool-down.

• Aerobic Training: Aerobic exercise included cycle ergometer. Exercise intensity was maintained at approximately 40-60% of maximum heart rate and RPE 11-13. Aerobic exercise was initially performed for approximately 20-30 minutes and progressively increased by 5 minutes every 2 weeks according to tolerance, up to a maximum of 60 minutes.

• Resistance Training: Exercises were performed for major upper- and lower-limb muscle groups using free weights. The initial resistance was approximately 50% of 10RM, with 10 repetitions per set. Exercises included functional lower-limb and upper-limb strengthening such as sit-to-stand, knee extension, heel raises, biceps curls and shoulder exercises. Rest intervals of approximately 1-2 minutes were provided between exercises/sets. Resistance was progressively increased according to the participant's tolerance and ability to complete the prescribed repetitions with proper technique.

• Inspiratory Muscle Training: IMT was performed using a Threshold Inspiratory Muscle Trainer. Participants performed 5 sets of 10 breaths per session, with 1minute rest between sets. Training intensity was progressively increased according to MIP: 50% MIP during weeks 1-3, 60% during weeks 4-6, 70% during weeks 7-9 and 80% during weeks 10-12, as tolerated.

During all sessions, exercise intensity was individualized according to vitals stability, patient tolerance and clinical condition. Heart rate, blood pressure, SpO₂, fatigue and symptoms were monitored throughout the intervention.

Group B - Conventional Physiotherapy with standard medical care :

Group B received conventional physiotherapy with standard medical care, consisting of general upper- and lower-limb mobility exercises, diaphragmatic breathing exercises, stretching and active range-of-motion exercises for 30-40 minutes per session, 3 days per week for 12 weeks.

Multidisciplinary Care

• Nephrologist: Conducted the initial CKD assessment, staging, medication review, blood pressure assessment and medical clearance before starting rehabilitation (Week 1). Medical review was repeated at Week 4, Week 8 and Week 12, or earlier if clinically indicated, to assess medical problems and exercise safety.
• Renal dietitian: Provided individualized renal dietary counselling at Week 1, including appropriate protein and energy intake, sodium, potassium, phosphorus and fluid management according to CKD stage and laboratory findings. Dietary follow-up was conducted at Week 4, Week 8 and Week 12 to reinforce dietary adherence and modify recommendations when required.
• Nurse: Monitored vital signs and exercise-related symptoms during every rehabilitation session throughout Weeks 1-12. The nurse also provided patient education, reinforced adherence to the exercise programme and coordinated with the rehabilitation team. Additional monitoring was performed whenever clinically required.

At the end of 12 weeks, all participants were reassessed using the same outcome measures. Pre- and post-intervention data were recorded and statistically analyzed to determine the effect of renal rehabilitation on pulmonary functions, functional capacity and fatigue.

Inclusion criteria

• Participants were medically diagnosed with moderate COPD (GOLD stage II-III) and were 40-70 years of age. Eligible participants included both males and females who were clinically stable, had the ability to understand and follow study instructions, and had a maximal inspiratory pressure (MIP) below 60 cmH₂O in males or below 50 cmH₂O in females

Exclusion criteria

• Patients were excluded if they had an acute COPD exacerbation, a cardiac pacemaker, unstable cardiovascular disease such as recent myocardial infarction or unstable angina, uncontrolled hypertension, or recent fractures.