Effects of Inspiratory Muscle Training on Dyspnea Perception During Exercise in Patients With COPD
Condition: COPD; Severe Systemic Illness-induced Respiratory Muscle Wasting
MeSH terms: Dyspnea; Respiratory Aspiration; Muscular Atrophy
Study type: Interventional

Summary: 
      Patients with chronic obstructive pulmonary disease are often limited in their exercise
      capacity by intolerable shortness of breath (dyspnea). Patients are breathing at high lung
      volumes during exercise which forces inspiratory muscles to work at a high percentage of
      their maximal capacity. This increased inspiratory effort has been shown to be independently
      related to symptoms of dyspnea during exercise in previous research. Eight weeks of high
      intensity variable flow resistive inspiratory muscle training is hypothesized to reduce
      inspiratory effort and to decrease neural drive to inspiratory muscles. These factors are
      hypothesized to jointly contribute to delaying the occurrence of intolerable symptoms of
      dyspnea and to improve exercise tolerance in these patients.
    

Detailed description: 
      We want to study whether a highly intense inspiratory muscle training program improves
      exercise capacity by reducing inspiratory effort, improving pulmonary mechanics and delaying
      the development of intolerable symptoms of dyspnea during cycle exercise. Eight weeks of high
      intensity variable flow resistive inspiratory muscle training is hypothesized to reduce
      inspiratory effort and to decrease neural drive to inspiratory muscles. The ratio of
      inspiratory effort to volume displacement should improve, and reductions of inspiratory
      capacity during exercise should be delayed. These factors are hypothesized to jointly
      contribute in delaying the occurrence of intolerable symptoms of dyspnea and to improve
      exercise tolerance in these patients.

      We will study physiological mechanisms by which inspiratory muscle training exerts its
      effects on dyspnea reduction and exercise capacity. In this clinical trial patients will be
      randomly allocated into either an intervention or a control group. The intervention group
      will receive a highly intense inspiratory muscle training program that will improve
      inspiratory muscle function. The control group will receive a sham training that will not
      result in physiological benefits.

      During the 8-week training period patients will have to attend the hospital once weekly for a
      short visit to perform a training session under supervision. Before the training intervention
      patients will be assessed twice and then again once after the 8-week program. This means that
      this trial will involve a total of 11 visits (3 long visits (approximately 4h) for
      assessments and 8 short visits (approximately 30 minutes) for supervised training sessions)
      over a period of 2-3 months. Assessments of pulmonary function, inspiratory muscle function,
      exercise capacity, daily physical activity and symptoms of dyspnea during exercise will be
      performed. Pulmonary mechanics and inspiratory muscle activation during exercise will also be
      assessed.

      Stable COPD patients with pronounced inspiratory muscle weakness (Pi,max < 70cmH2O or <70%
      predicted) will be eligible to participate in the study. Exclusion criteria will be diagnosed
      psychiatric or cognitive disorders, progressive neurological or neuromuscular disorders and
      severe orthopedic problems having a major impact on exercise capacity.

      Patients in both the intervention and the placebo group will follow an eight-week IMT
      program. They will receive either high intensity IMT (intervention group) or sham IMT
      (placebo group). Interventions will be presented to patients as strength training
      (intervention group) or endurance training (placebo group). Measurements of primary and
      secondary endpoints will be performed before and after 8 weeks of IMT. All tests will be
      performed by an experienced investigator that will be blinded to group allocation.

      Total training load for both groups will be two to three daily sessions of 30 breaths (3-4
      minutes per session), on 7 days per week, for 8 weeks. IMT will be performed using a variable
      flow resistive loading device(POWERbreathe®KH1, HaB International Ltd., Southam, UK).

      Differences in primary and secondary outcomes between groups after 8 weeks of IMT will be
      compared adjusting for baseline differences in an analysis of covariance (ANCOVA).

      Dyspnea perception on a 10-point Borg Scale (BORG CR10) at identical ventilation during the
      constant work rate cycling test after the intervention will be the primary outcome. To detect
      a difference of one point in the dyspnea perception on a 10-point Borg Scale at identical
      ventilation during the constant work rate cycling test after the intervention between
      subjects, assuming a standard deviation of the changes in dyspnea perception between baseline
      and follow-up measurement of 1 point with a degree of certainty (statistical power) of 80%
      and a risk for a type I error (a) < 5%, a sample size of 16 patients for each group is
      needed. These estimates are based on previous work on dyspnea perceptions during exercise.
    

Intervention name(s): Inspiratory Muscle Strength Training; Inspiratory Muscle Endurance Training
Intervention type(s): Device; Device
Intervention description(s): IMT will be performed using a variable flow resistive loading device (POWERbreathe®KH1, HaB International Ltd., Southam, UK). The device is able to store training parameters of up to 40 sessions. Most training sessions during this RCT will be performed by patients at their homes without supervision. The intervention group (strength IMT) will perform two daily sessions of 30 breaths. Measurements of Pi,max will be performed every week and training loads will be increased continuously to maintain at least 40-50% of the actual Pi,max values. Each week, one training session will be performed under supervision. Training load will be increased during this session.; IMT will be performed using a variable flow resistive loading device (POWERbreathe®KH1, HaB International Ltd., Southam, UK). The device is able to store training parameters of up to 40 sessions. Most training sessions during this RCT will be performed by patients at their homes without supervision. The sham group (endurance IMT) will perform three daily sessions of 30 breaths and will train at a constant inspiratory load of no more than 10% of their initial Pi,max. Each week, one training session will be performed under supervision.
Other intervention name(s): Electronic Variable Flow Resistive Loading IMT Device; POWERbreathe®KH1, HaB International Ltd., Southam, UK; Electronic Variable Flow Resistive Loading IMT Device; POWERbreathe®KH1, HaB International Ltd., Southam, UK
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Inspiratory Muscle Training; COPD; Inspiratory Muscle Function; Dyspnea