AI-Guided Predictions of Blood Pressure Dysregulation Using Perfusion Index as a Novel Biomarker in Persons With Spinal Cord Injury

The goal of this clinical trial is to determine if perfusion index (PI) can reliably predict changes in systolic blood pressure (SBP) in persons with spinal cord injury (SCI) during a cool temperature challenge. Participants with SCI can be 18-75 years of age, male or female, neurological level of injury C4-T12, ASIA Impairment Scale (AIS: A or B: motor complete) or gender and healthy age-matched able-bodied (AB) controls. The main question this study aims to answer is: can PI reliably predict change in SBP during a cool temperature challenge? The investigators hypothesize that PI can be used as a biomarker of SBP in persons with SCI. Researchers will compare the relationship of 1) changes in PI and SBP and 2) relationship of changes in other vital signs to SBP, during the cool temperature challenge. The researchers aim to determine if PI can be used as a biomarker of SBP in persons with SCI during a cool temperature challenge (experimental group/arm). Able-bodied controls (control group/arm) will receive the same intervention (cool challenge) as the experimental group. During the study, participants will be asked to wear only shorts and a T-shirt so that their skin can be exposed to the warm and cool temperatures of the 2 rooms. The investigators will put put on non-invasive sensors (taped or attached on the surface of your body) to measure PI, BP, and other vital signs. The investigators will record these measurements while the participant is seated in a wheelchair for 10 minutes in a warm room and up to 90 minutes in a cool room.