The Venous Distension Reflex and Orthostatic Hypertension
ConditionBlood Pressure
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorMilton S. Hershey Medical Center
About this trial
This research is being done to find out whether distension of veins in legs will cause a rise in blood pressure (orthostatic hypertension).
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Are capable of giving informed consent
Are of any race or ethnicity
Are fluent in written and spoken English
Whose history and physical exam did not uncover any
Disqualifiers
Are 18 years of age
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
The change in SBP by standing is within ± 5 mmHg from the supine SBP
Trial design
Design model
Parallel
Treatments tested in this trial
Tilt + external pressure
Other interventionIn 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.
Tilt + no external pressure.
Other interventionIn 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.
Limb occlusion + negative pressure
Other interventionIn 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.
Limb occlusion + no negative pressure
Other interventionIn 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.
Treatment groups
30 Participants
are divided into 4 treatment groupsGroup A: Tilt + external pressureExperimental treatment 1 intervention
Group B: Tilt + no external pressurePlacebo comparator 1 intervention
Group C: Limb occlusion + negative pressureExperimental treatment 1 intervention
Group D: Limb occlusion + no negative pressurePlacebo comparator 1 intervention
Trial outcomes
Primary outcomes
1
Muscle Sympathetic Nerve Activity (MSNA) in bursts/min or arbitrary units/min
MSNA provides direct recordings of sympathetic nerve activity directed to blood vessels in skeletal muscle.
Time frame
Recorded continuously during Visit 2, the 4-5 hr Negative Pressure study visit.Secondary outcomes
1
Blood pressure in mmHg
Cuffs placed on a finger and arm will monitor blood pressure.
Time frame
Recorded continuously during the 4-5 hr visit.2
Heart rate in beats per minute
Electrocardiogram (ECG) patches attached to a Cardiocap will monitor heart rate.
Time frame
Recorded continuously during the 4-5 hr visit.Sponsors and contacts
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Source ClinicalTrials.gov