A Study of Blood Pressure and Blood Supply to the Brain in Persons With a Spinal Cord Injury.

February 5, 2025 updated by: VA Office of Research and Development

Systemic Hemodynamics and Cerebral Blood Flow in Persons With Tetraplegia

The purpose of this study is to determine how blood pressure and blood flow are controlled during head-up tilt in a semi-upright position. In this investigation we are studying blood pressure and blood flow to the brain, with and without a medication which lowers blood pressure (Vasotec). We will determine how persons with a spinal cord injury are able to maintain blood flow to the brain (not get dizzy) as they assume a more upright position and their blood pressure decreases.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Individuals with tetraplegia lack normal sympathetic nervous system regulation of blood pressure and, therefore, relative hypotension is a common occurrence. This hypotension may be more pronounced with postural stress. Loss in mental acuity and sometimes even consciousness is an associated symptom of postural hypotension in individuals with tetraplegia.

There is some evidence to suggest that although mean arterial blood pressure (MAP) is relatively low in these individuals, middle cerebral arterial blood flow (CBF) may be maintained. Consequently, individuals with chronic tetraplegia often compensate and are stable in the seated upright position.

Autoregulation of CBF has been defined as the stability of cerebral blood flow throughout a range of systemic blood pressures (MAP). This proposal will examine systemic hemodynamics and middle cerebral artery blood flow during HUT with and without Vasotec, an angiotensin II inhibitor. By partially or completely ablating the renin-angiotensin system, which is postulated to play a major role in blood pressure regulation, the potential dissociation between systemic blood pressure and middle cerebral artery blood flow, in individuals with tetraplegia, may be demonstrated. The aim is to determine whether persons with chronic tetraplegia are able to maintain similar CBF, or similar CBF changes, as able-bodied controls despite a greater decrease in MAP to the same hypotensive challenge. The relationship between MAP and CBF has not been defined in this population. Understanding this relationship may lead to improved screening and treatment for prevention of postural hypotension in persons with tetraplegia.

Study Type

Interventional

Enrollment (Actual)

30

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • New York
      • Bronx, New York, United States, 10468
        • VA Medical Center, Bronx

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Duration of spinal cord injury (SCI) at least 1 year
  • Level of SCI C4-8 and T6 and below
  • matched non-SCI subjects
  • Chronological age between 18-65 years
  • Euhydration: Subjects will be instructed to avoid caffeine and alcohol and to maintain normal salt and water intake for several days prior to study.

Exclusion Criteria:

  • Known heart and/or blood vessel disease
  • Dehydration
  • High blood pressure
  • Kidney disease
  • Diabetes mellitus
  • Prescribed ACE inhibitors
  • Acute Infection
  • Smoking
  • Pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Health Services Research
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: ARM 1
Head-up tilt maneuver without drug in subjects with spinal cord injury
Other: Head up tilt (HUT)
45 degree head-up tilt to lower blood pressure and measure cerebral blood flow.
Placebo Comparator: ARM 3
Head-up tilt maneuver without drug in able-bodied controls
Other: Head up tilt (HUT)
45 degree head-up tilt to lower blood pressure and measure cerebral blood flow.
Active Comparator: ARM 2
Head-up tilt maneuver with an angiotensin converting enzyme inhibitor (1.25 mg enalaprilat) in subjects with spinal cord injury
Other: Head up tilt (HUT)
45 degree head-up tilt to lower blood pressure and measure cerebral blood flow.
Drug: 1.25 mg enalaprilat IV
an angiotensin converting enzyme (ACE) inhibitor given to lower blood pressure (BP) and measure cerebral blood flow (CBF)
Active Comparator: ARM 4
Head-up tilt maneuver with an angiotensin converting enzyme inhibitor (1.25 mg enalaprilat) in able-bodied controls.
Other: Head up tilt (HUT)
45 degree head-up tilt to lower blood pressure and measure cerebral blood flow.
Drug: 1.25 mg enalaprilat IV
an angiotensin converting enzyme (ACE) inhibitor given to lower blood pressure (BP) and measure cerebral blood flow (CBF)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Systolic Blood Pressure
Time Frame: acute testing
Systolic blood pressure during head-up tilt in subjects with spinal cord injury without drug intervention
acute testing

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cerebral Blood Flow
Time Frame: acute testing
Measurement of middle cerebral artery blood flow velocity supine and during head-up tilt
acute testing

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

VA Office of Research and Development

Investigators

  • Principal Investigator: Jill Wecht, EdD, VA Medical Center, Bronx

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

October 1, 2005

Primary Completion (Actual)

May 1, 2009

Study Completion (Actual)

April 1, 2012

Study Registration Dates

First Submitted

November 2, 2005

First Submitted That Met QC Criteria

November 2, 2005

First Posted (Estimated)

November 4, 2005

Study Record Updates

Last Update Posted (Actual)

March 25, 2025

Last Update Submitted That Met QC Criteria

February 5, 2025

Last Verified

February 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • B3346-V
  • 00517 (Other Identifier: JJP VAMC IRB)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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