Try our beta test site
IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more...

The Pathophysiology of Orthostatic Hypotension

This study is ongoing, but not recruiting participants.
Information provided by (Responsible Party):
David Robertson, Vanderbilt University Identifier:
First received: September 5, 2008
Last updated: April 19, 2017
Last verified: April 2017
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.

Condition Intervention Phase
Autonomic Nervous System Diseases
Orthostatic Hypotension
Dopamine Beta-Hydroxylase Deficiency
Orthostatic Intolerance
Procedure: Standing or upright tilt
Procedure: Microneurography
Procedure: QSweat
Device: neck cuff stimulation
Drug: phenylephrine,isoproterenol,nitroprusside,propranolol,edrophonium,atropine,tyramine
Drug: clonidine,yohimbine,metoclopramide,alpha-methyldopa
Procedure: BodPod
Procedure: Eye exam
Procedure: Sleep study
Procedure: Pain response testing
Procedure: Metabolic chamber
Procedure: Brain function studies
Procedure: Bicycle Exercise Test
Phase 1

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: No masking
Primary Purpose: Screening
Official Title: The Pathophysiology of Orthostatic Hypotension

Resource links provided by NLM:

Further study details as provided by Vanderbilt University Medical Center:

Primary Outcome Measures:
  • hemodynamic changes with standing [ Time Frame: following test ]

Secondary Outcome Measures:
  • blood and urine hormones [ Time Frame: after test ]
  • blood volume [ Time Frame: during supine and/or upright postures ]
  • sympathetic nerve activity [ Time Frame: during stimulation of sympathetic nervous system ]
  • quantitative sweat testing [ Time Frame: 2 hours ]
  • Eye function [ Time Frame: once ]
  • Sleep efficiency [ Time Frame: once ]
  • Metabolic rate [ Time Frame: once ]
  • Pain response [ Time Frame: once ]
  • Responses on questionnaires and computer tasks designed to assess brain function [ Time Frame: once ]

Estimated Enrollment: 25
Study Start Date: December 1996
Estimated Study Completion Date: December 2017
Estimated Primary Completion Date: December 2017 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: A
Patients with Orthostatic Hypotension
Procedure: Standing or upright tilt
stand upright or tilt table test
Procedure: Microneurography
Recording from sympathetic nerve
Procedure: QSweat
quantitative sweat testing
Device: neck cuff stimulation
Blood pressure receptors in the neck arteries may be stimulated by applying suction through a collar around the neck.
Drug: phenylephrine,isoproterenol,nitroprusside,propranolol,edrophonium,atropine,tyramine

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

Drug: clonidine,yohimbine,metoclopramide,alpha-methyldopa

Oral Pharmacological Testing

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

Procedure: BodPod
Determination of body composition
Procedure: Eye exam

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

  1. 0.5% proparacaine (Alcaine, Allergan, Inc)
  2. Fluress (0.4% benoxinate hydrochloride, fluorescein sodium, Akorn, Inc)
  3. 0.5%, 1% tropicamide (Mydriacyl, Alcon)
  4. Over-the-counter preservative-free artificial tears
  5. 0.25%, 2.5% and 10% phenylephrine (Bausch and Lomb)
  6. 1% cyclopentolate hydrochloride (Alcon)
Procedure: Sleep study
Recording of sleep pattern overnight
Procedure: Pain response testing
Subjects will rate the quality and intensity of 2 pain tasks.
Procedure: Metabolic chamber
Determination of metabolic rate via 24hr stay in whole-room indirect calorimeter
Procedure: Brain function studies
Questionnaires and computer tasks, an EEG and an MRI may be used to assess brain function.
Procedure: Bicycle Exercise Test
Blood pressure and heart rate may be monitored while exercising on a stationary bicycle.


Ages Eligible for Study:   12 Years to 70 Years   (Child, Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00748059

United States, Tennessee
Vanderbilt University
Nashville, Tennessee, United States, 37232
Sponsors and Collaborators
Vanderbilt University
Principal Investigator: David Robertson, MD Vanderbilt University
Study Director: Emily M Garland, PhD Vanderbilt University
  More Information

Additional Information:
Responsible Party: David Robertson, Professor, Vanderbilt University Identifier: NCT00748059     History of Changes
Other Study ID Numbers: 030752
Study First Received: September 5, 2008
Last Updated: April 19, 2017

Keywords provided by Vanderbilt University Medical Center:
autonomic nervous system diseases
blood pressure

Additional relevant MeSH terms:
Nervous System Diseases
Orthostatic Intolerance
Hypotension, Orthostatic
Autonomic Nervous System Diseases
Primary Dysautonomias
Vascular Diseases
Cardiovascular Diseases
Neurologic Manifestations
Signs and Symptoms
Antihypertensive Agents
Vasodilator Agents
Nitric Oxide Donors
Molecular Mechanisms of Pharmacological Action
Adrenergic beta-Agonists
Adrenergic Agonists
Adrenergic Agents
Neurotransmitter Agents processed this record on April 25, 2017