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NCT Number: NCT00748059

The Pathophysiology of Orthostatic Hypotension

The purpose of this study is to determine the cause of low blood pressure in selective patients who have problems with their involuntary (autonomic) nervous system. These patients frequently have had symptoms throughout their life, and their disorder might have a genetic basis. The biochemical, physiological and pharmacological procedures in this study should help us define the problem and perhaps lead to more effective treatment.

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Key information

Conditions

Autonomic Nervous System Diseases Cardiovascular Diseases Dizziness Dopamine Beta-Hydroxylase Deficiency Hypotension Hypotension, Orthostatic Nervous System Diseases Neurologic Manifestations Orthostatic Hypotension Orthostatic Intolerance Pathological Conditions, Signs and Symptoms Primary Dysautonomias Sensation Disorders Signs and Symptoms Vascular Diseases dopamine beta hydroxylase deficiency

Age range

12 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

Vanderbilt University

Nashville, Tennessee, 37232, United States

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • severe orthostatic hypotension and other autonomic symptoms but do not meet criteria for standard diagnosis
  • non-smokers
  • drug-free
  • able to give informed consent
  • free of pulmonary, renal, hematopoietic, hepatic and cardiac disease

Exclusion criteria

  • medications affecting the autonomic nervous system
  • any chronic illness
  • anemia (Hct<30)
  • women of childbearing age who are pregnant or nursing
  • smokers

Treatment and study plan

Standing or upright tilt

Procedure

stand upright or tilt table test

Microneurography

Procedure

Recording from sympathetic nerve

QSweat

Procedure

quantitative sweat testing

neck cuff stimulation

Device

Blood pressure receptors in the neck arteries may be stimulated by applying suction through a collar around the neck.

phenylephrine,isoproterenol,nitroprusside,propranolol,edrophonium,atropine,tyramine

Drug

IV Pharmacological Testing

phenylephrine 12.5 - 400 ug, isoproterenol 0.1 - 0.4 ug or higher until desired effect, nitroprusside 0.1 - 1.6 ug/kg, propranolol 1.1 mg/min, edrophonium maximum of 10 mg, atropine .01 mg/kg, tyramine 250-4000 ug or higher until desired effect

clonidine,yohimbine,metoclopramide,alpha-methyldopa

Drug

Oral Pharmacological Testing

clonidine 0.1-0.3 mg, yohimbine 5-10 mg, metoclopramide 10 mg, alpha-methyldopa 62.5 mg, placebo

BodPod

Procedure

Determination of body composition

Eye exam

Procedure

Examination of pressure in the eye and eyelid fatiguability. The following eyedrops might be used:

  • 0.5% proparacaine (Alcaine, Allergan, Inc)
  • Fluress (0.4% benoxinate hydrochloride, fluorescein sodium, Akorn, Inc)
  • 0.5%, 1% tropicamide (Mydriacyl, Alcon)
  • Over-the-counter preservative-free artificial tears
  • 0.25%, 2.5% and 10% phenylephrine (Bausch and Lomb)
  • 1% cyclopentolate hydrochloride (Alcon)

Sleep study

Procedure

Recording of sleep pattern overnight

Pain response testing

Procedure

Subjects will rate the quality and intensity of 2 pain tasks.

Metabolic chamber

Procedure

Determination of metabolic rate via 24hr stay in whole-room indirect calorimeter

Brain function studies

Procedure

Questionnaires and computer tasks, an EEG and an MRI may be used to assess brain function.

Bicycle Exercise Test

Procedure

Blood pressure and heart rate may be monitored while exercising on a stationary bicycle.

Primary outcomes

  1. hemodynamic changes with standing

    Time frame: following test

Secondary outcomes

  1. blood and urine hormones

    Time frame: after test

  2. blood volume

    Time frame: during supine and/or upright postures

  3. sympathetic nerve activity

    Time frame: during stimulation of sympathetic nervous system

  4. quantitative sweat testing

    Time frame: 2 hours

  5. Eye function

    Time frame: once

  6. Sleep efficiency

    Time frame: once

  7. Metabolic rate

    Time frame: once

  8. Pain response

    Time frame: once

  9. Responses on questionnaires and computer tasks designed to assess brain function

    Time frame: once

Sponsors and collaborators

Lead sponsor

Vanderbilt University Medical Center

Other

Registry information

Important dates

Study start
1996
Primary completion
2020
Study completion
2020
First posted
Sep 8, 2008
Registry last updated
May 12, 2021

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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