Body Temperature in Persons With Tetraplegia When Exposed to Cold
Condition: Tetraplegia; Hypothermia; Mild Cognitive Impairment
MeSH terms: Quadriplegia; Hypothermia; Cognitive Dysfunction
Intervention: Midodrine hydrochloride
Intervention description: Midodrine hydrochloride is an approved medication used to treat low blood pressure. We are using a standard dose of 10 mg (tablet) only one time to determine if the effects of this drug improve the ability to maintain body core temperature in a cool environment (off-label use). A physician will administer the drug once before the cool thermal challenge in subjects with tetraplegia only(Visit 2)
Intervention MeSH terms: Midodrine
Phase: Phase 4
Study type: Interventional
Allocation: Non-Randomized
Intervention model: Factorial Assignment
Masking: None (Open Label)
Enrollment: 30.0
Sex: All
Minimum age: 18 Years
Maximum age: 68 Years
Healthy volunteers: Accepts Healthy Volunteers
Keywords: Quadriplegia; Spinal Cord Injuries; Body Temperature Regulation; Mild Cognitive Impairment

Summary:

      The ability to maintain normal body core temperature (Tcore = 98.6°F) is impaired in persons
      with tetraplegia. Despite the known challenges to the ability of persons with spinal cord
      injury (SCI) to maintain Tcore, and the effects of hypothermia to impair mental function in
      able-bodied (AB) persons, there has been no work to date addressing these issues in persons
      with tetraplegia.

      The aim of this study is to determine if exposure of up to 2 hrs to cool temperatures (64°F)
      causes body core temperature to decrease in persons with tetraplegia and if that decrease is
      related to a decrease in mental performance.

      After sitting in a cool (64°F) room for up to 2 hours the investigators hypotheses are:

      Hypotheses (1): Tcore of most of the persons with tetraplegia will decline approximately
      1.8°F (e.g., 98.6 to 96.8°F) while Tcore of controls will not decline at all; (2) Most of the
      persons with tetraplegia will show a decline in mental performance (memory or
      clear-headedness) while only some of AB controls will show a decline.

      The second aim of this study is to determine if a 10 mg dose of an approved blood pressure
      raising medicine (midodrine hydrochloride) will (1) reduce the decrease in body core
      temperature and (2) prevent or delay the decline in mental performance in the group with
      tetraplegia compared to the exact same procedures performed on the day with no medicine
      (Visit 1) in the same group.

      Hypotheses (3 & 4): The changes in blood flow to the skin caused by taking a one-time dose of
      midodrine will lessen the decline in Tcore and prevent or delay the decline in mental
      performance compared to the changes in Tcore and mental performance during cool temperature
      exposure without midodrine in the group with tetraplegia.
    

Eligibility criteria:

        Inclusion Criteria:

          -  (1) Between 18 and 68 years of age;

          -  (2) Duration of injury ≥ 1 year; (2) Level of SCI C3-T1;

          -  (3) Euhydration (subjects will be instructed to avoid caffeine and alcohol, maintain
             normal salt and water intake, and avoid strenuous exercise for 24 hours prior to
             study)

        Exclusion Criteria:

          -  (1) Known coronary heart, kidney, peripheral vascular or cerebral vascular disease;

          -  (2) High blood pressure;

          -  (3) Untreated thyroid disease;

          -  (4) Diabetes mellitus;

          -  (5) Acute illness or infection;

          -  (6) Dehydration;

          -  (7) Known allergies to midodrine hydrochloride;

          -  (8) Smoking;

          -  (9) Pregnancy