Can ventilation improve posture?
Raphael is a 52-year-old man with CP, LD, asthma and h/o respiratory failure. He has complex seating needs: pelvic obliquity ↑L, scoliosis concave L, reduced L hip flexion (75º), and R posterior rib hump. He also has a large abdominal mass.
Rafael has extreme temperature regulation issues and tends to scratch his knees and forehead as well as develop redness on his back. His mum manages this by:
- changing his T-shirt 4x/day
- constantly wiping perspiration off his face
- four fans to cool him down
- changing in situ slings 2x/day
- towel behind his back
Seating and positioning Rafael has always been challenging as he requires a close-fitting seating system due to his complex seating needs and impingement issues. Rafael’s longstanding issues with overheating and perspiration all year round also prove to be a challenging factor when manufacturing an intimate seating system.
Victoria detailed Rafael’s long journey to cool him down: “Rafael had tried most if not all of the solutions available. Each solution had its own merits and worked in their own way. The Matrix/Lynx, MSI provided rigid, excellent postural support but was hot and a little too firm for Rafael. We also tried carved foam seating and later carved foam with holes in for air flow. This was more forgiving on Rafael’s skin but still too hot. Matrix and Lynx allowed for airflow with its open structure but in this case, did not do enough to keep Rafael cool. His mum had used up to four desk fans behind and in front of the chair, but the padding that lines the seating didn’t allow for effective ventilation and wasn’t very portable. We also tried a few of the smart materials like bamboo covers, but they did not provide a noticeable enough improvement to make Rafael more comfortable. We had also tried a more careful design of the custom seat, making sure only to contact Rafael on load-bearing surfaces to allow for natural air movement as possible.”
While some solutions offered slight improvements, nothing drastically influenced his ability to cool. It was after this journey that Victoria met Corien, our founder, at the Naidex trade show and learned about wheelAIR. Rafael’s Occupational Therapist, Suzanna Shari, saw the clinical need for wheelAIR system for Rafael, which is how the case for funding was made.
Victoria also detailed the process of how she integrated the wheelAIR system into Rafael’s mould:
“We made a copy of his current seating and material was removed from the centre of the backrest. The wheelAIR rubber channels were imbedded into the backrest with a double layer of padding over the channels. The padding we tried first was what we would typically use, a 15mm thick layer of viscoelastic foam over the LD24 Plasterzote backrest. The viscoelastic foam did not allow for the convention of air from the wheelAIR defeating the object. Next, we tried a combustion modified foam which suffered from the same problem. Finally, we settled on the honeycomb SupraCore glued LD24, with his original towelling cover which includes a thin layer of combustion modified padding sewn inside the cover.”
The prototype back worked really well!
- uses 1- 2 shirts a day (was 4)
- His mother no longer has to wipe perspiration from his face
- no longer need to change in situ slings
- no towel required behind his back
- no longer scratches his head and knees
- reduction of redness to his back
However… The supra core was peeling off.
The thin layer of foam in the backrest cover nullified the effects of the wheelAIR, so mum was not using them. After a little trial and error with some materials, we found the Polyvent bonded securely to Plasterzote.
We purchased some Polyvent and brought Rafael back into the clinic. The SupraCore was removed, and Polyvent was used to line the backrest. We placed a double layer over the channels just in case. New covers were made from a spacer material and issued back to Rafael.”
After a 12 month study, it has become clear that the wheelAIR has significantly improved Rafael’s life and that of those around him. He now needs his clothes changed only once per day and barely shows any sign of sweating anymore.
Anyone that has been to a humid environment knows that heat is not as tolerable as a dry environment at the same temperature, but why?
The human sweat system is extremely effective in maintaining a constant temperature. Our pores open, release water and salt to the skin surface, and as the water evaporates, it transfers heat into the air. Thanks to the convection cycle, this warm air moves away and is replaced by cooler air ready to absorb more heat from the skin cooling you down further.
If the moisture content in the surrounding air is low, the sweat on your skin evaporates quickly. If it is humid, the sweat will struggle to evaporate, making it less effective. The rate of evaporation has a direct impact on how cool you feel.
In the case of custom seating, a layer of air is trapped. Heat and moisture can escape into this small layer of air, but it will heat up quickly and become humid in a short time. Materials covering the seating and clothing the user can absorb some of this moisture, drawing it away from the user, but they will also become saturated over time. Smart materials for the covers (such as spacer fabrics) might help reduce the rate of this, but they were not effective enough in Rafael’s case.
Forcing the air to move with a fan or vacuum, replaces the trapped humid air with dryer air which gives the bodies temperature regulation system a chance to work. We can make careful choices in padding and seating materials to accommodate natural convection as much as possible, but sometimes this is not enough. Sometimes additional energy must be added into the system to allow for temperature regulation.