Development of a Novel Cooling Vest to Prevent Heat-Induced Thermoregulatory Dysfunction in Persons with Spinal Cord Injury

Persons with spinal cord injury (SCI), particularly those with injuries above T6 (Hi-SCI), are unable to effectively regulate core body temperature (Tcore) due to interruption of motor, sensory, and sympathetic pathways. Interruption of sympathetic pathways limits central regulation of vasodilation and sweating for increasing heat

loss and vasoconstriction for decreasing heat loss. Thus, when exposed to ambient heat, limited control of cutaneous vasodilation and sweating impairs the ability to maintain a constant Tcore. Persons with Hi-SCI often find themselves in hot environments for prolonged periods during social, religious, or work functions, especially

during warmer seasons or when in hot climate zones. They report rapidly progressing to feeling “overheated,” uncomfortable, and fatigued during even limited exposure to conditions considered as mildly hot by able-bodied (AB) controls. During these times, their dramatic rise in Tcore can reach hyperthermia (≥38°C) and, if allowed to

progress, can lead to heat stroke, causing seizures, loss of consciousness, and potentially death. Interventions that address the increased risk for heat-related illness in persons with SCI are limited. Therefore, continuing development of our feedback-controlled ”smart” cooling vest and testing its safety and efficacy to sufficiently

dissipate body heat to compensate for thermodysregulation, is absolutely vital to minimize the adverse effects on health and quality of life that most Veterans with Hi-SCI experience during exposure to warm temperatures. The goals of this pilot study are to: 1) further develop and test the safety and tolerability of a self-regulating

cooling vest in AB participants, and 2) determine the efficacy of the cooling vest to provide protection from an excessive rise in Tcore and thermal discomfort during warm exposure in Veterans with Hi-SCI. Five AB participants and ten participants with Hi-SCI (C4-T2, AIS A-B) will be recruited for study. AB participants will be

observed to ensure the safety of the vest, which will be determined by assessing skin temperatures and subjective thermal sensation beneath the vest during 2 hours of warm exposure (35°C). In participants with Hi- SCI during 2 hours of warm exposure (35°C), a repeated measures experimental design for [two-conditions (wet

vest, no vest)] is being proposed to demonstrate the efficacy of the cooling vest to attenuate the expected rise in Tcore and thermal discomfort. Primary Objective (Safety): In a warm thermal chamber (35°C), AB participants will wear the wet cooling vest at maximal setting for 2 hours in the seated position to determine: (1) minimum skin temperatures beneath the

wet cooling vest, and (2) subjective comfort of the wet cooling vest (safety testing). Primary Hypotheses: AB participants will demonstrate (1) All skin temperatures beneath the vest will be ≥20°C.

(2) All participants will report a thermal sensation (TS) ≥ “cool” (not “cold” or “very cold”) (Zhang 9-point Thermal Sensation scale). Secondary Objective (Efficacy in SCI): On 2 separate days, participants with Hi-SCI will wear either the wet cooling vest [or no vest] (in random order) for up to 2 hours in the seated position in a warm thermal chamber

(35°C) to determine: (1) change in Tcore, and (2) change in thermal comfort (efficacy testing). Secondary Hypotheses: Participants with Hi-SCI wearing the wet cooling vest when in the warm environment will have the following findings: 1) 65% will demonstrate a significantly reduced elevation in Tcore (≤0.3°C)

than the expected mean increase (0.6±0.3°C) in the [no vest condition], and 2) a greater percentage of participants with SCI will report a decreased perception of heat and thermal discomfort (Zhang 6-point Thermal Comfort scale) than the expected perceptions of “hot or very hot” and “uncomfortable” that will be reported in

the [no vest condition].