Body Temperature in Persons With Tetraplegia When Exposed to Cold

Plain-language 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.

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