Heated Vest for Persons With Spinal Cord Injury
Condition: Spinal Cord Injuries
MeSH terms: Spinal Cord Injuries; Wounds and Injuries
Study type: Interventional

Summary: 
      Persons with higher levels of spinal cord injury (above the 2nd thoracic vertebrae;
      tetraplegia) are unable to maintain normal core body temperature (Tcore) when exposed to cool
      environments. In persons with tetraplegia, even limited exposure to cool temperatures may
      cause Tcore to approach hypothermic values and impair cognitive performance. Conversely, an
      increase in Tcore from subnormal to normal range may improve cognitive performance. Prior
      work has shown that cool seasonal temperatures have an adverse effect on personal comfort and
      the ability to perform vital daily activities of self-care in persons with tetraplegia.
      Interventions that address the vulnerability to hypothermia are limited. A self-regulating
      heated vest designed specifically for persons with tetraplegia is a novel and promising
      strategy to address this problem. By more effectively maintaining Tcore, the vest can
      decrease the adverse impact of cool temperatures on comfort, quality of life, and performance
      of vital daily tasks for Veterans with tetraplegia during the cooler seasons.
    

Detailed description: 
      Persons with spinal cord injury (SCI), particularly cervical injuries (tetraplegia), are
      unable to effectively regulate core body temperature (Tcore) due to interruption of motor,
      sensory, and sympathetic pathways. Thus, control of distal extremity vasoconstriction (heat
      conservation) and shivering thermogenesis (heat production) are impaired, and the ability to
      maintain a constant Tcore is compromised. Persons with tetraplegia often report "feeling
      cold," frequently present with subnormal Tcore (35-36.5 degrees C), and are particularly
      vulnerable to hypothermia (Tcore<35 degrees C) and associated impairment in cognitive
      performance, even when exposed to temperatures that are comfortable for able-bodied (AB)
      individuals. Cool seasonal temperatures have been shown to have a greater adverse effect on
      personal comfort, activities of daily living (ADLs), and vital daily activities in persons
      with tetraplegia than that of AB controls. Conversely, a minimal increase in Tcore from
      subnormal to normothermia, secondary to ambient heat may improve cognitive performance.
      Interventions addressing the tendency to poikilothermia and enhanced vulnerability to
      hypothermia in persons with tetraplegia are limited. Therefore, exploration of safe and
      efficacious bioengineering solutions to address the physiological, cognitive, and quality of
      life (QoL) issues associated with the routine exposure to cool temperatures that persons with
      tetraplegia often encounter is warranted.

      The goals of this pilot study are to: 1) fully bench-test the heated vest for safety before
      performing any human subject testing; 2) study the safety and tolerability of a
      feedback-controlled heated vest in AB controls; and 3) study the efficacy of this heated vest
      to minimize the expected decline in Tcore and associated deterioration of cognitive
      performance during 2 hours of cool exposure in persons with tetraplegia.

      In persons with tetraplegia, a two-condition (heated vest, non-heated vest) prospective study
      is being proposed to compare the physiological and cognitive responses to 2 hours of
      controlled cool exposure (18 degrees C) with a prototype heated vest vs. a similar, but
      non-heated vest (control condition). Eight subjects with tetraplegia (C3-T1, AIS A and B) and
      eight AB controls will be recruited for study participation. Before the prototype is tested
      on human subjects, it will have been fully bench tested and have satisfied all safety
      requirements and specifications. AB subjects will be observed to ensure the safety of the
      vest, which will be accomplished by determining the temperatures of the vest ( 39 degrees C)
      and subjective thermal sensation of no greater than "warm" during a cool condition that will
      be identical to the condition which subjects with SCI will be exposed. Subjects with
      tetraplegia will test the efficacy of the heated vest, i.e. preventing the expected decline
      in Tcore and cognitive performance and increase in thermal comfort.

      After the feedback-controlled heated vest has been fully bench-tested and has satisfied all
      safety requirements (interior vest temperature does not exceed 39 degrees C at maximal power)
      and design specifications (lightweight, slim, easy to don doff), the following specific aims
      will be addressed:

      Primary Specific Aim: In a cool thermal chamber (18 degrees C), AB controls will wear the
      heated vest at maximal setting for 120 minutes in the seated position to determine (1)
      maximum temperatures of all areas of the interior (user's side) of the heated vest and (2)
      subjective comfort of the heated vest (safety testing).

      Primary Hypotheses: The study of AB controls will demonstrate (1) All areas under the vest
      will have temperatures 39 degrees C. (2) All subjects will report a thermal sensation no
      greater than "warm" this would include identification of "hot spots" (Zhang 9-point Thermal
      Sensation Scale).

      Secondary Specific Aim: During exposure to a cool environment (18 degrees C) for up to 120
      minutes in the seated position, persons with tetraplegia will wear the heated vest to
      determine (1) change in Tcore, (2) change in cognitive performance, and (3) change in thermal
      comfort (efficacy testing).

      Secondary Hypotheses: In persons with tetraplegia wearing the heated vest compared to the
      same persons wearing the non-heated vest, it's expected that (1) 30% of the subjects will
      have a decline of 0.5 degrees C in Tcore compared with 80% in the control condition, (2) 30%
      of the subjects will demonstrate a decline of at least 1 T-score in at least one of the
      following measures: Interference of Stroop Color and Word test, Digit Span of Wechsler Adult
      Intelligence Scale-Fourth Edition, compared with 80% in the control condition, and (3) a
      greater percentage of subjects reporting increased thermal comfort (Zhang 6-point Comfort
      Scale).
    

Intervention name(s): Heated Vest; Non-Heated Vest
Intervention type(s): Device; Device
Intervention description(s): Heated vest that regulates its heat output based on the user's skin, the user's core temperature, and the ambient temperature; A similarly insulated (compared to the experimental vest), but non-heated vest
Other intervention name(s): Feedback-controlled heated vest; Active comparator vest, control condition
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: After the heated vest has 1) been fully bench-tested and 2) satisfied safety and tolerability testing in able-bodied subjects, it will be tested in persons with tetraplegia using a crossover design with the order of the two visits randomized.
Thermal Challenge with heated vest (subjects with tetraplegia only): Subjects with tetraplegia, while seated and wearing only a standard T-shirt and shorts, will be fitted with an appropriately sized heated vest. Subjects will be transferred to a pre-cooled thermal chamber and data will be collected for up to 2 hours with the self-regulating heated vest.
Thermal Challenge with non-heated vest (subjects with tetraplegia only): The same subjects with tetraplegia (from Visit 2), while seated and wearing only a standard T-shirt and shorts, will be fitted with an appropriately sized, similar, but non-heated vest. Subjects will be transferred to a pre-cooled thermal chamber and data will be collected for up to 2 hours.
Masking: None (Open Label)
Primary purpose: Other
Keywords: Hypothermia; Body Temperature Regulation; Cognition