The Venous Distension Reflex and Orthostatic Hypertension
Milton S. Hershey Medical Center
30 participants
Mar 10, 2020
INTERVENTIONAL
Conditions
Summary
This research is being done to find out whether distension of veins in legs will cause a rise in blood pressure (orthostatic hypertension).
Eligibility
Inclusion Criteria3
- Are capable of giving informed consent
- Are of any race or ethnicity
- Are fluent in written and spoken English
Exclusion Criteria15
- Are 18 years of age
- For subjects with elevated standing BP
- Systolic BP (SBP) during standing is at least 10 mmHg \> the supine SBP
- Patients with a diagnosis of stage I hypertension without other chronic diseases may be INCLUDED
- For normal subjects without elevated standing BP
- The change in SBP by standing is within ± 5 mmHg from the supine SBP
- Matched gender, similar age and BMI (within 10%) to participants with elevated standing BP
- Free of acute or chronic medical conditions
- Age \< 18 years of age
- Are a pregnant or nursing woman
- Are a prisoner or institutionalized individual or unable to consent
- Have chronic diseases (e.g. heart, lung, neuromuscular disease, or cancer) other than stage I hypertension
- Have orthostatic hypotension or a history of syncope
- Current smoker
- History of blood clots
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Interventions
In Visit 1, the anti-shock trousers will be inflated to 20, 40, or 60 mmHg. BP will be measured 3 times from the brachial artery. Then the table will be tilted head up to a maximum of 70o for up to 10 min, while BP will be measured from the brachial artery at 1 min intervals. The tilt table is returned to 0o and the resting supine baseline BP will be collected. Then, the anti-shock trousers will be inflated to a different pressure (20, 40, or 60 mmHg) and the head up tilt will be repeated. Repetitions at the various pressures will be performed in a random order with suitable resting intervals in between the tilting bouts.
In Visit 1, the anti-shock trousers will NOT be inflated. Auscultatory BP will be measured 3 times from the brachial artery. Thereafter, the table will be tilted head up to a maximum of 70o for up to 10 min, while BP will be measured from the brachial artery at 1 min intervals.
In Visit 2, a cuff will be placed on the thigh of a leg that is sealed in an airtight pressure tank. After the cuff is inflated to 250 mmHg, the pressure in the tank will be reduced to -100mmHg for 2 minutes. The application of negative pressure creates a suction effect on the leg, and leads to an overall increase in pressure gradient across the blood vessel wall and induces vascular distension.
In Visit 2, a cuff will be placed on the thigh of a leg that is sealed in an airtight pressure tank. The cuff is inflated to 250 mmHg for 2 minutes, but the pressure in the tank is not changed.
Locations(1)
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NCT03496792