Blood Pressure
Conditions
Brief summary
To determine if 24-hr ambulatory blood pressure monitoring effects endothelial function, we will measure flow-mediated dilation before and after the blood pressure monitoring (ischemia conditioning).
Detailed description
Reestablishing blood flow (reperfusion) to organs that had their blood supply restricted (ischemia) can cause damage to the vasculature via injury and tissue death resulting in endothelial dysfunction. This ischemia-reperfusion (blood flow occlusion and resupply) triggered injury can be reduced or prevented by preceding brief periods of ischemia called preconditioning. Properly-performed preconditioning can exert a powerful protection against a subsequent sustained period of ischemia in a variety of organs in the body including the heart, kidney, and skeletal muscle. Preconditioning protocol involves repeated brief inflation and deflation of a blood pressure cuff. In many of human cardiovascular research studies, it is common to measure endothelial function and ambulatory (24-hour) blood pressure. The ambulatory blood pressure device takes repeated blood pressure readings every 15-30 minutes during the daytime and 30-60 minutes at night. It is possible that repeated bouts of inflation/deflation of the blood pressure cuff could induce preconditioning effects and influence endothelial function. Therefore, in the proposed study we aim to address this hypothesis.
Interventions
DEVICEAmbulatory (24-hour) Blood Pressure
Unlike casual blood pressure measurements, 24-hour ambulatory blood pressure monitoring provides an insight into blood pressure changes in everyday life and an estimate of the overall blood pressure load exerted on the cardiovascular system over 24 hours. Blood pressure recordings over a 24-hour period of normal daily activity will be made using a noninvasive ambulatory monitor (Spacelabs, Redlands, WA). The ambulatory system will be calibrated against a mercury sphygmomanometer, and the cuff will be programmed to inflate automatically every 15 min from 6 AM to 11 PM and every 20 min between 11 PM and 6 AM. For each individual subject, the nighttime period will be defined as the time when the subject goes to bed at night until rising in the morning. Daytime will be defined as the remainder of the 24-hour period. Daytime and nighttime states will be monitored by an Actiwatch (Mini-MItter, Bend, OR), a watch-like device placed on the wrist that measures gross motor activity.
Sponsors
University of Texas at Austin
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
OTHER
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
30 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
Adults aged between 30 to 60 years old.
Exclusion criteria
Exclusion from the study may be due to: i) pregnancy (by asking the subjects when the last time she had menstruation; we do have simple testing kits available if a subject is unsure about her status); ii) a recent illness, recent surgery, or any medical intervention in the 48 hours before any of the study days; iii) personal history of diabetes (fasting blood glucose \> 126 mg/dL), heart disease, or other cardiovascular problems.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change From Baseline in Flow Mediated Dilation After 24 Hour Ischemic Conditioning With Blood Pressure Cuff | Baseline, Post 24 hour conditioning | Flow-mediated dilatation (FMD) is a common and non-invasive method to assess vascular endothelial function by measuring the Brachial artery's responsiveness (diameter percent increase) following a brief period of occlusion. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Ambulatory (24-hour) Blood Pressure Ambulatory (24-hour) Blood Pressure: Unlike casual blood pressure measurements, 24-hour ambulatory blood pressure monitoring provides an insight into blood pressure changes in everyday life and an estimate of the overall blood pressure load exerted on the cardiovascular system over 24 hours. Blood pressure recordings over a 24-hour period of normal daily activity will be made using a noninvasive ambulatory monitor (Spacelabs, Redlands, WA). The ambulatory system will be calibrated against a mercury sphygmomanometer, and the cuff will be programmed to inflate automatically every 15 min from 6 AM to 11 PM and every 20 min between 11 PM and 6 AM. For each individual subject, the nighttime period will be defined as the time when the subject goes to bed at night until rising in the morning. Daytime will be defined as the remainder of the 24-hour period. | 22 |
| Total | 22 |
Baseline characteristics
| Characteristic | Ambulatory (24-hour) Blood Pressure |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 22 Participants |
| Age, Continuous | 41 years STANDARD_DEVIATION 8 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 8 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 14 Participants |
| Region of Enrollment United States | 22 participants |
| Sex: Female, Male Female | 10 Participants |
| Sex: Female, Male Male | 12 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 22 |
| other Total, other adverse events | 0 / 22 |
| serious Total, serious adverse events | 0 / 22 |
Outcome results
Primary
Change From Baseline in Flow Mediated Dilation After 24 Hour Ischemic Conditioning With Blood Pressure Cuff
Flow-mediated dilatation (FMD) is a common and non-invasive method to assess vascular endothelial function by measuring the Brachial artery's responsiveness (diameter percent increase) following a brief period of occlusion.
Time frame: Baseline, Post 24 hour conditioning
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Intervention | Change From Baseline in Flow Mediated Dilation After 24 Hour Ischemic Conditioning With Blood Pressure Cuff | 6.6 percentage of baseline | Standard Deviation 2 |