High-intensity Inspiratory Muscle Training as a Pre-cardiac Rehabilitation After CABG Surgery

Sponsor

University of Illinois at Chicago (Other)

Overall Status

Not yet recruiting

CT.gov ID

NCT06127147

Collaborator

TUBİTAK (Other)

Enrollment

Location

Arms

Anticipated Duration (Months)

6.3

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

Background/aim: The success of coronary artery bypass graft (CABG) surgery depends on the long-term patency of the grafts used. Many factors can lead to endothelial dysfunction, especially depending on the vascular properties of arterial grafts. Endothelial function determines the long-term patency of bypass grafts and the occurrence of atherosclerotic disease. On the other hand, repeated large fluctuations in inspiratory pressures during high-intensity inspiratory muscle training (IMT) protocols can induce shear stress in the systemic circulation and hemodynamic changes that stimulate adaptations in the large elastic arteries and heart. Thus, it may provide improvements in nitric oxide-mediated endothelial function by stimulating some changes in cardiovascular functions. The aim of this study is to investigate and interpret whether high-intensity inspiratory muscle training, beyond the usual care after CABG surgery, improves endothelial function and arterial stiffness.

Methods: The study was designed as a randomized controlled trial. Patients will be allocated for inspiratory muscle training (IMT) with 60% of maximum inspiratory pressure (MIP) or sham inspiratory muscle training (Sham-control), for 4 weeks. In both groups, before and after 4-week training, cardiovascular functions will be measured and compared.

Condition or Disease	Intervention/Treatment	Phase
Coronary Artery Bypass Graft CABG	Device: IMT Device: Sham-IMT	N/A

Detailed Description

Background: The success of coronary artery bypass graft (CABG) surgery depends on the long-term patency of the grafts used. Many factors can lead to endothelial dysfunction, especially depending on the vascular properties of arterial grafts. Endothelial function determines the long-term patency of bypass grafts and the occurrence of atherosclerotic disease. Many physio-pathological events that cause the initiation and maintenance of vascular damage by endothelial dysfunction are triggered, and this, together with risk factors, reduces the success rate in CABG surgeries. Also, endothelial dysfunction can promote arterial stiffness that causes elevations in systolic blood pressure due to increased vascular resistance. Inspiratory muscle training is basically training consisting of repeated inspirations against resistance. Inspiratory muscle training has also been applied to patients with chronic disease or as an additional therapy for cardiac rehabilitation and it has proven to be safe in these groups. Few studies in the literature examined the effects of both preoperative and postoperative inspiratory muscle training in patients undergoing cardiac surgery. Most of them have investigated the effect of low-intensity inspiratory muscle training. There are only three studies in the literature examining the effects of high-intensity inspiratory muscle training after CABG surgery. However, these studies did not reveal the direct effects of inspiratory muscle training on vascular functions. On the other hand, repeated large fluctuations in inspiratory pressures during high-intensity inspiratory muscle training protocols can induce shear stress in the systemic circulation and hemodynamic changes that stimulate adaptations in the large elastic arteries and heart. Thus, it may provide improvements in nitric oxide-mediated endothelial function by stimulating some changes in cardiovascular functions. To the best of our knowledge, the effects of inspiratory muscle training after CABG surgery on endothelial function and arterial stiffness have not been investigated in the literature yet.

Aim: The aim of this study is to investigate and interpret whether high-intensity inspiratory muscle training, beyond the usual care after CABG surgery, improves endothelial function and arterial stiffness.

Methods: The study was designed as a randomized controlled trial. After coronary artery bypass graft surgery, patients will be invited to the study. The demographic and clinical characteristics of the patients will be recorded after consent is obtained from the volunteer patients who meet the inclusion criteria. Subsequently, patients will be randomly divided into two groups for inspiratory muscle training (IMT) with 60% maximum inspiratory pressure (MIP) or sham inspiratory muscle training (Sham-control), for 4 weeks. In both groups, before and after 4-week training, resting blood pressure (systolic/diastolic), resting heart rate, endothelial function, arterial stiffness, functional exercise capacity, the severity of dyspnea and inspiratory muscle functions will be measured.

Study Design

Study Type:

Interventional

Anticipated Enrollment :

44 participants

Allocation:

Randomized

Intervention Model:

Parallel Assignment

Masking:

Double (Participant, Outcomes Assessor)

Primary Purpose:

Treatment

Official Title:

Effects of High-intensity Inspiratory Muscle Training as a Pre-cardiac Rehabilitation Intervention on Cardiovascular Functions in Patients After Coronary Artery Bypass Graft Surgery

Anticipated Study Start Date :

Nov 20, 2023

Anticipated Primary Completion Date :

May 20, 2024

Anticipated Study Completion Date :

Jun 20, 2024

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Study Group Patients who will perform inspiratory muscle training (IMT) with %60 of MIP intensity	Device: IMT The IMT protocol will consist of high-intensity daily training - 2 sets of 30 breaths with a 1-minute rest between sets, twice a day for 4 weeks using an IMT Threshold device (Threshold IMT Philips® Respironics, Inc). The intensity of the training will be set to 60% of each patient's maximal inspiratory pressure.
Sham Comparator: Sham Group Patients who will perform Sham-IMT	Device: Sham-IMT The sham IMT protocol will consist of high-intensity daily training - 2 sets of 30 breaths with a 1-minute rest between sets, twice a day for 4 weeks using an IMT Threshold device (Threshold IMT Philips® Respironics, Inc) without intensity.

Arm

Intervention/Treatment

Experimental: Study Group

Patients who will perform inspiratory muscle training (IMT) with %60 of MIP intensity

Device: IMT

The IMT protocol will consist of high-intensity daily training - 2 sets of 30 breaths with a 1-minute rest between sets, twice a day for 4 weeks using an IMT Threshold device (Threshold IMT Philips® Respironics, Inc). The intensity of the training will be set to 60% of each patient's maximal inspiratory pressure.

Sham Comparator: Sham Group

Patients who will perform Sham-IMT

Device: Sham-IMT

The sham IMT protocol will consist of high-intensity daily training - 2 sets of 30 breaths with a 1-minute rest between sets, twice a day for 4 weeks using an IMT Threshold device (Threshold IMT Philips® Respironics, Inc) without intensity.

Outcome Measures

Primary Outcome Measures

inspiratory muscle function [4 weeks]
maximal inspiratory pressure (MIP) is the highest pressure measured during inspiration will be used.
endothelial function [4 weeks]
flow-mediated dilation (FMD) ultrasound measurements of brachial artery flow-mediated dilatation will be performed.
arterial stiffness [4 weeks]
arterial stiffness will be assessed by measuring pulse wave velocity.

Secondary Outcome Measures

functional exercise capacity [4 weeks]
maximal distance in 6 minute walk test will be used.
dyspnea [4 weeks]
The modified Medical Research Council (mMRC) Dyspnea Scale, which have 5 points (0 to 4) will be used. High scores presented worsen dyspnea.

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years and Older

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Inclusion Criteria:

Aged >18 years old
Be able to walk independently.
Had coronary artery bypass graft (CABG) surgery
Sufficient English language comprehension and cognitive ability to understand the study protocol, give informed consent and follow instructions.

Exclusion Criteria:

Being a current smoker (or tobacco).
Having a diagnosed chronic disease such as inflammatory bowel disease/irritable bowel syndrome, cerebrovascular diseases, COPD, chronic kidney disease requiring dialysis, neurological disorders, or diseases that may affect motor/cognitive function [multiple sclerosis, Parkinson's disease, polio, Alzheimer's disease, dementia, or other brain diseases of ageing])
Getting a score below 24 on the Standardized Mini Mental Test
Using antipsychotic medications commonly used to treat schizophrenia or schizoaffective disorders (i.e., haloperidol)
Having had any other previous cardiothoracic operation except CABG (e.g. Pneumonectomy, lobectomy, etc.)
Having a history of unstable-angina
Having had pneumonia in the last 3 months