Effects of Inspiratory Muscle Training on Maximal Inspiratory Pressure, Cardiopulmonary Capacity, and Quality of Life in Patients With Heart Failure
试验速览
- 阶段
- 不适用
- 状态
- Enrolling By Invitation
- 入组人数
- 60
- 试验地点
- 1
- 主要终点
- Change in Maximal Inspiratory Pressure (MIP)
研究概览
简要总结
The purpose of this study is to compare the effects of three different modalities of inspiratory muscle training (IMT) in patients diagnosed with chronic heart failure who exhibit reduced or mid-range left ventricular ejection fraction (LVEF < 50%). Patients will be recruited from cardiac rehabilitation programs and must be clinically stable before entering the protocol.
The study has a total duration of 8 weeks and is divided into two distinct phases. During the first 2 weeks, participants will undergo a familiarization phase to learn the proper breathing techniques with the devices and to complete baseline resting and functional clinical evaluations. The following 6 weeks will comprise the effective training phase, consisting of 3 weekly sessions of high-intensity inspiratory training.
Participants will be randomly assigned to one of three parallel groups:
- Group 1 (Pressure-Threshold IMT): Participants will train using a mechanical pressure-threshold device at an initial high-intensity load of 60% of their baseline maximal inspiratory pressure (MIP).
- Group 2 (Electronic Flow-Resistive IMT): Participants will train at a high-intensity load of 60% of their baseline MIP utilizing the PowerBreathe KH2 electronic device, which provides a dynamic, flow-dependent automated resistance.
- Group 3 (Control / Sham IMT): Participants will perform the same breathing protocol but using a mechanical device set at a low, non-training intensity of 15% of their baseline MIP.
For all three groups, training volume is standardized to 5 sets of 8 repetitions (40 inspiratory efforts per session). To ensure progressive overload, training intensity will be increased by 10% of the initial baseline MIP value every 2 weeks.
The main outcomes to be evaluated before and immediately after the 8-week period include maximal inspiratory muscle strength, structural changes in respiratory muscles (diaphragmatic and parasternal intercostal thickening fraction measured via ultrasound), cardiac autonomic balance (heart rate variability), and health-related quality of life. Additionally, dynamic responses such as respiratory and locomotor muscle oxygenation (measured continuously via Near-Infrared Spectroscopy [NIRS] during a respiratory metabolic reflex provocation test) and overall cardiopulmonary exercise capacity (measured via an incremental cycle ergometer test) will be analyzed.
This study aims to determine which training modality provides the most effective physiological adaptations to optimize rehabilitation in this population.
详细描述
This clinical trial aims to explore the underlying physiological mechanisms and comparative systemic adaptations of mechanical pressure-threshold versus electronic flow-resistive inspiratory muscle training (IMT) in patients with Heart Failure with Reduced Ejection Fraction (HFrEF). Patients with HFrEF frequently exhibit respiratory muscle weakness, which triggers an early activation of the inspiratory muscle metaboreflex. This reflex increases sympathetic vasoconstrictor drive to active locomotor muscles, accelerating peripheral fatigue, exacerbating dyspnea, and limiting overall exercise tolerance.
To systematically address these mechanisms, the protocol is structured into a precise multi-stage timeline distributed over 8 consecutive weeks:
- Methodological Familiarization and Baseline Testing (Weeks 1-2):
To eliminate the confounding "learning effect" and ensure internal data validity, the first two weeks are exclusively dedicated to patient technical habituation. Participants will learn proper diaphragmatic breathing techniques, device interface seal (using flanged mouthpieces and nose clips), and device manipulation under submaximal loads. Concurrently, baseline clinical profiling will be conducted, including spirometry, maximal inspiratory pressure (MIP), resting cardiac autonomic balance through Heart Rate Variability (HRV), and central vascular stiffness via Pulse Wave Velocity (PWV). 2. High-Intensity Standardized Intervention (Weeks 3-8):
The formal training phase lasts 6 weeks with a frequency of 3 supervised sessions per week, totaling 18 effective sessions. To preserve biomechanical quality and prevent disproportionate dyspnea or early neuromuscular fatigue in this clinical population, the training volume is strictly set to 5 sets of 8 repetitions (40 breathing efforts per session), separated by standardized resting intervals.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- Double (Care Provider, Outcomes Assessor)
盲法说明
To minimize performance bias, the clinical staff supervising the daily training sessions (care providers) will remain completely blinded to group allocations, as devices and digital interfaces will be pre-configured and delivered using coded identifiers. Furthermore, the external investigator responsible for primary data acquisition and testing (cardiopulmonary exercise testing and diaphragmatic ultrasound) will remain strictly blinded to group assignments. Finally, the statistician conducting the analysis in R will handle all datasets using randomized codes, which will be broken only after processing all outcomes.
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Documented clinical diagnosis of chronic Heart Failure with Reduced Ejection Fraction (HFrEF) according to the European Society of Cardiology (ESC) guidelines.
- •Left Ventricular Ejection Fraction (LVEF) less than or equal to 40% documented by echocardiography within the last 12 months.
- •Clinically stable condition for at least 3 months prior to enrollment, with no hospitalizations or major changes in optimized medical therapy.
- •New York Heart Association (NYHA) functional class I to IV.
- •Evidence of inspiratory muscle weakness, defined as a baseline Maximal Inspiratory Pressure (MIP) < 70% of the predicted value for age and sex.
- •Age greater than or equal to 18 years.
- •Patient must be capable of understanding the protocol instructions and must provide signed written informed consent.
排除标准
- •Presence of primary severe pulmonary or respiratory diseases (e.g., Chronic Obstructive Pulmonary Disease [COPD] GOLD stage III or IV, active asthma, severe pulmonary hypertension, or restrictive lung disease).
- •Recent myocardial infarction, unstable angina, or coronary artery bypass graft (CABG) surgery within the last 6 months.
- •Severe uncorrected valvular heart disease or complex, uncontrolled ventricular arrhythmias.
- •Orthopedic, neurological, or musculoskeletal limitations that prevent the safe execution of an incremental cardiopulmonary exercise test on a cycle ergometer or the performance of the isometric handgrip protocol.
- •Cognitive impairment or psychological conditions that limit the ability to follow instructions, maintain correct diaphragmatic breathing technique, or properly seal the training device mouthpiece.
- •Current participation in another structured physical rehabilitation or formal sports training program that could confound the systemic results of the intervention.
- •Any acute infectious, inflammatory, or medical condition that, in the investigator's opinion, poses a safety risk during high-intensity training.
结局指标
主要结局
Change in Maximal Inspiratory Pressure (MIP)
时间窗: Baseline (Week 0) and post-intervention (Week 9).
Maximal Inspiratory Pressure (MIP) will be assessed from residual volume using a calibrated digital manometer according to standardized international guidelines. The highest value obtained from at least three reproducible maneuvers (varying less than 10%) will be recorded to quantify changes in volitional inspiratory muscle strength
Change in Peak Oxygen Consumption (VO2 peak)
时间窗: Baseline (Week 0) and post-intervention (Week 9).
Peak oxygen consumption will be evaluated during a incremental symptom-limited cardiopulmonary exercise test (CPET) on a cycle ergometer using a breath-by-breath metabolic cart to assess changes in aerobic capacity.
Change in Health-Related Quality of Life via Minnesota Living with Heart Failure Questionnaire (MLHFQ)
时间窗: Baseline (Week 0) and post-intervention (Week 9).
Changes in disease-specific health-related quality of life will be assessed using the unabbreviated Minnesota Living with Heart Failure Questionnaire (MLHFQ). The total score ranges from 0 to 105, where a higher score indicates a worse health-related quality of life and greater symptom limitation.
次要结局
- Change in Ventilatory Efficiency (VE/VCO2 slope)(Baseline (Week 0) and post-intervention (Week 9).)
- Change in Multi-Muscle Tissue Oxygen Saturation Kinetics (SmO2)(Baseline (Week 0) and post-intervention (Week 9).)
- Change in Diaphragmatic and Parasternal Intercostal Ultrasound Parameters(Baseline (Week 0) and post-intervention (Week 9).)
- Change in Inspiratory Muscle Endurance Time(Baseline (Week 0) and post-intervention (Week 9).)
研究者
Gabriel Ignacio Garrido Cerda
Principal investigator and Doctoral Candidate, PhD in Rehabilitation Sciences at Andres Bello University
Universidad Nacional Andres Bello