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Heat and Spinal Cord Injuries

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SCI and Thermoregulation

It is well established that a complete cervical spinal cord injury has the most profound effect on thermoregulation. Individuals with a spinal cord injury (SCI) have impaired autonomic thermoregulation, causing a loss of vasomotor control and sweating below the level of lesion due to the disruption of the sympathetic nervous system (Yoda et al, 2015).

Consequently, they are susceptible to more pronounced changes in core body temperature than able-bodied individuals and both hypothermia and hyperthermia are potentially fatal complications of exposure to extreme temperatures (Schmidt & Chan, 1992). As a result, people with a.SCI are advised to avoid extremes in ambient temperature.

This is particularly acute during exercise. Tetraplegic individuals do not show the characteristic plateau in core temperature of paraplegic and able-bodied subjects during exercise in cool conditions because of severe reduction or complete absence of cooling mechanisms (Price, 2006). Even exercising in a room with 50% relative humidity results in a striking reduction in the ability to thermoregulate, especially in quadriplegics (Petrofsky, 1992). Furthermore, the sweat rates observed in the quadriplegics when working in a hot environment reflect a much higher regional sweat rate than for paraplegic or able-bodied individuals (Petrofsky, 1992).

Although the increased participation in wheelchair sports has stimulated interest into the study of thermoregulation of wheelchair users (Price, 2006), there is a need for more cooling strategies that meet the demands of intermittent wheelchair exercise (Griggs et al, 2014).

Behavioural modification is seen as the best thermoregulatory mechanism for persons with high-level spinal cord injuries (Schmidt and Chan, 1992). This was confirmed in later research which found that individuals with a SCI could sense the change of ambient temperature equally well as able-bodied participants, which should allow them to control body temperature behaviourally (Yoda et al, 2015).

The WheelAir system is designed specifically to provide effective temperature regulation for individuals with spinal cord injuries. Through active and controlled airflow, the system galvanises the body’s heat exchange mechanism at the skin surface to aid thermoregulation control. The WheelAir creates a cool microclimate by reducing skin temperature and allows for heat and moisture exchange that is otherwise occluded when using a normal backrest.

Our research shows that with a normal backrest on an active wheelchair, the back temperature already rises on average 2.2 C̊ or 7% after 30 minutes. WheelAir is most effective when used preventively, ensuring the user’s back and body stays at a constant temperature, reducing fatigue and heat stress, and improving comfort. By selecting the right airflow setting in the right environment, WheelAir can avoid that 7% (2.2 C̊ ) temperature rise all together.


References

Griggs, K. E., Price, M. J., & Goosey-Tolfrey, V. L. (2014). Cooling Athletes with a Spinal Cord Injury. Sports Medicine, 45(1), 9-21. doi:10.1007/s40279-014-0241-3

Petrofsky, J. S. (1992). Thermoregulatory stress during rest and exercise in heat in patients with a spinal cord injury. European Journal of Applied Physiology and Occupational Physiology, 64(6), 503-507. doi:10.1007/bf00843758

Price, M. J. (2006). Thermoregulation during Exercise in Individuals with Spinal Cord Injuries. Sports Medicine, 36(10), 863-879. doi:10.2165/00007256-200636100-00005

Schmidt, K. D., & Chan, C. W. (1992). Thermoregulation and Fever in Normal Persons and in Those With Spinal Cord Injuries. Mayo Clinic Proceedings, 67(5), 469-475. doi:10.1016/ s0025-6196(12)60394-2

Yoda, T., Griggs, K. E., Leicht, C. A., & Goosey-Tolfrey, V. L. (2015). The effect of increased ambient temperature on thermoregulatory responses in spinal cord injured people. Extreme Physiology & Medicine, 4(S1). doi:10.1186/2046-7648-4-s1-a157