Breathing & Blood Pressure
Study Details
Study Description
Brief Summary
The purpose of this study is to determine the effect of obesity on cardiovascular responses during various breathing maneuvers.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
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Detailed Description
Adults with higher body mass can have trouble breathing during exercise, which could be due to high respiratory muscle workloads. These breathing muscles can require a lot of energy, which takes away energy from other (e.g., leg) muscles. Participating in this study will help us understand how the heart and blood vessels respond during brief exercise and during various breathing maneuvers.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Adults without obesity body mass index below 30 kg/m^2 |
|
| Adults with obesity body mass index above 30 kg/m^2 |
Outcome Measures
Primary Outcome Measures
- Blood pressure during respiratory muscle testing [Up to one week]
Systolic and diastolic blood pressure measured in the laboratory at rest, during eucapnic voluntary hyperpnea, and during inspiratory muscle strength training
- Blood pressure during exercise [Up to one week]
Systolic and diastolic blood pressure measured in the laboratory at rest, during handgrip exercise, and during an incremental aerobic exercise test
Secondary Outcome Measures
- Laboratory-measured blood pressure [Up to one week]
Systolic and diastolic blood pressure measured in the laboratory
- Ambulatory blood pressure [Up to one week]
Systolic and diastolic blood pressure measured at home using an automated monitor
- Flow-mediated dilation (FMD) [Up to one week]
Flow-mediated vasodilation will be assessed using continuous measures of brachial artery diameter and velocity via duplex Doppler ultrasound. The brachial artery will be imaged in the longitudinal plane proximal to the medial epicondyle using a high-frequency linear-array probe. Shear rate (sec-1) will be calculated as [(blood flow velocity (cm*s-1) *4)/blood vessel diameter (mm)] The image will be recorded throughout a 60-s baseline, a 300-s ischemic stimulus (250 mmHg), and 180 seconds post deflation. FMD will be expressed as % dilation (final diameter-baseline diameter/baseline diameter x100) and also normalized to the shear stimulus. Allometric scaling will be used if appropriate, including if there are baseline differences in artery diameter between groups
- Arterial stiffness [Up to one week]
The investigators will assess pulse wave velocity (PWV) using a high-fidelity strain-gauge transducer to obtain the pressure waveform at the carotid and femoral artery. Distances from the carotid artery sampling site to the femoral artery (upper leg instrumented with a thigh cuff), and from the carotid artery to the suprasternal notch will be recorded. PWV will be expressed as cm/s.
- Cardiovagal baroreflex sensitivity [Up to one week]
The investigators will assess cardiovagal baroreflex sensitivity (ms/mmHg) using 1) the sequence method by calculating the slope between increases and decreases in R-R interval (ms) and systolic blood pressure (mmHg); and 2) during the Valsalva maneuver.
- Inspiratory muscle strength [Up to one week]
Peak inspiratory pressure measured in the laboratory
- Inspiratory muscle endurance [Up to one week]
Time until exhaustion during an respiratory muscle endurance test
- Dyspnea in daily life [Up to one week]
Participants will complete the modified Medical Research Council scale (numerical scores of 0-4, with 4 being the greatest breathlessness).
- Rate of oxygen uptake during eucapnic voluntary hyperpnea [Up to one week]
Participants will wear a facemask that will allow for collection of expired air in a system capable of measuring oxygen concentration as well as flow and volume. Thus, the system will report the rate of oxygen uptake (ml of oxygen per minute) and the expiratory flow (ml of total air volume per minute).
Other Outcome Measures
- Forced expiratory volume in one second (FEV1) [Up to one week]
The investigators will measure this variable using spirometry
- Forced vital capacity (FVC) [Up to one week]
The investigators will measure this variable using spirometry
- Rate of oxygen uptake and minute ventilation during aerobic exercise [Up to one week]
Participants will wear a facemask that will allow for collection of expired air in a system capable of measuring oxygen and carbon dioxide concentrations as well as flow and volume. Thus, the system will report the rate of oxygen uptake (ml of oxygen per minute) and the expiratory flow (ml of total air volume per minute).
- Rating of perceived exertion and breathlessness during aerobic exercise [Up to one week]
Participants will report their rating of perceived exertion (numerical scores of 6-20, with 20 being the greatest exertion) and breathlessness (numerical scores of 0-10, with 10 being the greatest breathlessness) based on two validated scales at rest and during an incremental aerobic exercise test.
- Rating of perceived exertion and breathlessness during handgrip exercise [Up to one week]
Participants will report their rating of perceived exertion (numerical scores of 6-20, with 20 being the greatest exertion) and breathlessness (numerical scores of 0-10, with 10 being the greatest breathlessness) based on two validated scales at rest and during handgrip exercise
- Muscle sympathetic nerve activity (MSNA) and sympathetic transduction [Up to one week]
The investigators will directly record MSNA using an active tungsten microelectrode using standard microneurography techniques. MSNA will be expressed as bursts per minute. Further, the investigators will measure common femoral artery blood flow using ultrasound and mean blood pressure. This will allow determination of sympathetic transduction (the vasoconstrictor and pressor effects of MSNA) expressed as changes in blood pressure (mmHg) or changes in vascular conductance (ml/min/mmHg).
Eligibility Criteria
Criteria
Inclusion Criteria:
• Body mass index values of 18-40 kg/m^2
Exclusion Criteria:
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Not weight stable (<5% change in body mass over the past six months)
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Overt cardiovascular, neurological, renal, liver, and/or metabolic illness (e.g., diabetes mellitus)
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Current, or history of uncontrolled, Stage 2 hypertension (blood pressure >140 / 90 mmHg; anti-hypertensive medications are permitted)
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Diagnosed obstructive sleep apnea
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Previous bariatric surgery
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Diagnosis or signs (e.g., values below the lower limit of normal) of overt airway disease(s)
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Current or recent (regular use within the past 6 months) use of tobacco or nicotine products (e.g., cigarettes, vaping)
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Per the POWERbreathe® company:
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Patients who have undergone recent abdominal surgery and those with abdominal hernia.
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Asthma patients who have a very low symptom perception and suffer from frequent, severe exacerbations or with an abnormally low perception of dyspnoea.
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If a patient is suffering from a ruptured eardrum or any other condition of the ear.
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Patients with marked elevated left ventricular end-diastolic volume and pressure.
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Patients with worsening heart failure signs and symptoms after a respiratory/inspiratory muscle training (IMT) session
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If you are suffering from a cold, sinusitis, or respiratory tract infection, we advise that you do not use your POWERbreathe IMT device.
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Individuals who are not yet adults (infants, children, teenagers)
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Pregnant (self-reported and urine pregnancy test conducted), lactating (self-reported), or post-menopausal (self-reported) females
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Prisoners
Contacts and Locations
Locations
No locations specified.Sponsors and Collaborators
- Florida State University
Investigators
- Principal Investigator: Joseph Watso, PhD, Florida State University
Study Documents (Full-Text)
None provided.More Information
Additional Information:
Publications
None provided.- STUDY00003469