Research in seat design and comfort has seen continued growth, especially for those who have lost the ability to control their thermoregulatory feedback mechanisms. These mechanisms would usually warn the user for impeding skin damage due to hyper-humidity and hyperthermia [1].
The thermal properties (heat absorption and dissipation) of a cushion and backrest clearly play a vital role in comfort. Furthermore, research shows it could also have an influence on tissue viability and consequently skin ulcer formation [2] [3].
While finding the correct pressure relieving cushion or backrest is important, the risk of excessive heat and moisture build-up in a backrest can heavily impact the risk of pressure ulcer development [4]. Our research shows that while using a normal backrest on an active wheelchair, back temperature already rises on average 2.2˚C or 7% after 30 minutes.
This graph outlines back temperature responses to four WheelAir airflow levels in different ambient environments:
Graph 1-4: Isothermal Airflow Intensity in Ambient Temperatures 10˚C to 37˚C.
Once the back temperature has risen above the starting neutral, WheelAir has the possibility of cooling the user’s back temperature by 2.5˚C within three minutes, dropping further as time progresses.
The graph below indicates the average temperature differences for three different test groups. These results were obtained by using WheelAir at the highest setting. Over a prolonged period of time, the back temperature seems to stabilise with the ambient environment temperature. This indicates that there would be no build-up of heat and moisture.
Read our clinical Indications Q&A
Extra notes:
* Each client’s individual circumstances and conditions must be considered against the full range of equipment and interventions available. The WheelAir backrest will be just one of many considerations and individual needs and preferences will vary in every case.
*A study by Sales et al. (2017) to define the thermal comfort of seats through infrared thermography observed that in most seats the temperatures of the backrest and the seat behave similarly.
* The goal should be to keep the core temperature around 36.5-37.5˚C, and skin temperature at 32˚C.
*There is a case to be made when evaluating WheelAir as an individual environmental control system against a generally controlled environmental temperature. A study showed that by using an individual control system not only the thermal management of the participant improved, but their satisfaction increased too.
* Important to note is that the WheelAir has built-in channels that guide the airflow, spreading it evenly over the user’s back, rather than blasting airflow on one specific point of the user’s back.
[1] Liu, Z., Wang, L., Luo, Z., Heusch, A., Cascioli, V. and McCarthy, P. (2015). Microenvironment temperature prediction between body and seat interface using autoregressive data-driven model. Journal of Tissue Viability, 24(4), pp.131-139.
[2] Huizenga C, Hui Z, Arens E. A model of human physiology and comfort for assessing complex thermal environments. Build Environ 2001;36:691e9.
[3] Andersen ES, Karlsmark T. Evaluation of four non-invasive methods for examination and characterization of pressure ulcers. Skin Res Technol 2008;14:270e6.
[4] Freeto, T., Cypress, A., Amalraj, S., Yusufishaq, M. and Bogie, K. (2016). Development of a Sitting MicroEnvironment Simulator for Wheelchair Cushion Assessment. Journal of Tissue Viability, 25, pp.175-179.