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

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ClinicalTrials.gov Identifier: NCT00248807
Recruitment Status : Completed
First Posted : November 4, 2005
Results First Posted : June 23, 2014
Last Update Posted : June 23, 2014
Sponsor:
Information provided by (Responsible Party):
VA Office of Research and Development ( US Department of Veterans Affairs )

Study Description
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Brief Summary:
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.

Condition or disease Intervention/treatment Phase
Orthostatic Hypotension Spinal Cord Injuries Drug: 1.25 mg enalaprilat IV Other: Head up tilt (HUT) Not Applicable

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 Design
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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 30 participants
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Health Services Research
Official Title: Systemic Hemodynamics and Cerebral Blood Flow in Persons With Tetraplegia
Study Start Date : October 2005
Actual Primary Completion Date : May 2009
Actual Study Completion Date : April 2012

Resource links provided by the National Library of Medicine

Drug Information available for: Enalaprilat

Arms and Interventions
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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
 Drug: 1.25 mg enalaprilat IV
an angiotensin converting enzyme (ACE) inhibitor given to lower blood pressure (BP) and measure cerebral blood flow (CBF)

Other: Head up tilt (HUT)
45 degree head-up tilt to lower blood pressure and measure cerebral blood flow.
Active Comparator: ARM 4
Head-up tilt maneuver with an angiotensin converting enzyme inhibitor (1.25 mg enalaprilat) in able-bodied controls.
 Drug: 1.25 mg enalaprilat IV
an angiotensin converting enzyme (ACE) inhibitor given to lower blood pressure (BP) and measure cerebral blood flow (CBF)

Other: Head up tilt (HUT)
45 degree head-up tilt to lower blood pressure and measure cerebral blood flow.


Outcome Measures
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Primary Outcome Measures :
  1. Systolic Blood Pressure [ Time Frame: acute testing ]
    Systolic blood pressure during head-up tilt in subjects with spinal cord injury without drug intervention


Secondary Outcome Measures :
  1. Cerebral Blood Flow [ Time Frame: acute testing ]
    Measurement of middle cerebral artery blood flow velocity supine and during head-up tilt


Eligibility Criteria
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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

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
Contacts and Locations
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Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00248807


Locations
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United States, New York
VA Medical Center, Bronx
Bronx, New York, United States, 10468
Sponsors and Collaborators
US Department of Veterans Affairs
Investigators
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Principal Investigator: Jill Wecht, EdD VA Medical Center, Bronx
More Information
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Publications of Results:

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Responsible Party: US Department of Veterans Affairs
ClinicalTrials.gov Identifier: NCT00248807    
Other Study ID Numbers: B3346-V
00517 ( Other Identifier: JJP VAMC IRB )
First Posted: November 4, 2005    Key Record Dates
Results First Posted: June 23, 2014
Last Update Posted: June 23, 2014
Last Verified: May 2014
Keywords provided by VA Office of Research and Development ( US Department of Veterans Affairs ):
Blood Pressure, Low
Hypotension, Postural
Injuries, Spinal Cord
Spinal Cord Transection
Spinal Cord Trauma
Additional relevant MeSH terms:
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Spinal Cord Injuries
Hypotension, Orthostatic
Hypotension
Wounds and Injuries
Spinal Cord Diseases
Central Nervous System Diseases
Nervous System Diseases
Trauma, Nervous System
Vascular Diseases
Cardiovascular Diseases
 Orthostatic Intolerance
Primary Dysautonomias
Autonomic Nervous System Diseases
Enalaprilat
Enalapril
Angiotensin-Converting Enzyme Inhibitors
Protease Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Antihypertensive Agents