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

Condition(s) targeted: Orthostatic Hypotension; Spinal Cord Injuries

Intervention: 1.25 mg enalaprilat IV (Drug); Head up tilt (HUT) (Other)

Phase: N/A

Status: Recruiting

Sponsored by: Department of Veterans Affairs

Official(s) and/or principal investigator(s):
Jill Wecht, EdD, Principal Investigator, Affiliation: VA Medical Center, Bronx

Overall contact:
Jill Wecht, EdD, Email: jm.wecht@va.gov

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.

Official title: Systemic Hemodynamics and Cerebral Blood Flow in Persons With Tetraplegia

Study design: Health Services Research, Non-Randomized, Open Label, Parallel Assignment

Primary outcome: cerebral blood flow and blood pressure

Detailed description: Individuals with tetraplegia lack normal sympathetic nervous system regulation of blood pressure and therefore, relative hypotension is a common occurrence, which 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 however, 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-angiotension 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.

Minimum age: 18 Years. Maximum age: 65 Years. Gender(s): Both.

Criteria:

Inclusion Criteria:

1. Duration of spinal cord injury (SCI) 1 year

2. Level of SCI C4-8 and T6 and below

3. matched non-SCI subjects

4. Chronological age between 18-65 years

5. 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:

1. Known heart and/or blood vessel disease

2. Dehydration

3. High blood pressure

4. Kidney disease

5. Diabetes mellitus

6. Prescribed ACE inhibitors

7. Infection

8. Smoking

9. Pregnancy

Jill Wecht, EdD, Email: jm.wecht@va.gov

VA Medical Center, Bronx, Bronx, New York 10468, United States; Recruiting
Dwindally Rosado Rivera, EdD, Phone: 718-584-9000, Ext: 3128, Email: dwindally.rosadorivera@va.gov
Jill Wecht, EdD, Principal Investigator

Starting date: October 2005
Ending date: October 2009
Last updated: September 9, 2008