Accidents can happen to anyone, anytime, anywhere. From motor vehicle accidents, penetrating injuries due to stab wounds to an elderly suffering a fall, all can cause spinal cord injuries leading to sudden-onset paralysis. Prolonged immobilisation in a wheelchair because of paralysis comes with severe, life-threatening complications of pressure ulcers, leading to the invention of the wheelchair seating training system (WSET).
The system was based on a request by the Rehabilitation Medicine specialists, whereby they needed a system to train new wheelchair users to perform wheelchair pressure relief on the buttocks and back area, the prolonged seating body part, and to develop good pressure relieving habits.
As such, Associate Professor Dr Nur Azah Hamzaid of Universiti Malaya (UM) Department of Biomedical Engineering took up this request by her Rehabilitation Medicine colleagues to come up with a solution.
Together with her UM Master of Engineering Science graduate Norhani Md Nadzri, also from the Department of Biomedical Engineering, they have won the Gold Award in the 35th International Invention, Innovation & Technology Exhibition (ITEX) 2022 for the development and showcase of this wheelchair seating training system.
“WSET is designed as an assistive tool that monitors and reminds patients to perform pressure relief activities for one minute after every 30 minutes of sitting in a wheelchair. The target group are paraplegic spinal cord injury patients who are able to use their hands but require the use of a wheelchair in their daily life,” said Norhani.
According to Norhani, pressure ulcers are localised damage that happens to the skin or underlying tissue due to pressure with a combination of shear. As most patients with spinal cord injury spend over eight hours in a wheelchair for mobility and most are unable to sense the pressure on their buttocks and back. The prolonged sitting increases thermal conductivity and pressure on the buttock, especially areas of bony prominences. Consequently, these areas suffer from insufficient blood flow and delivery of nutrients, leading to ulcer development which could potentially lead to death if measures are not taken.
“To prevent pressure ulcers, wheelchair paraplegic patients are advised to conduct pressure relief activities depending on their level of cervical cord injury and physical capabilities. There are various techniques involved, such as lateral trunk shift, forward trunk lean and shoulder depression. However, the challenge is reminding patients to do it as most individuals with spinal cord injury do not sense pain or irritation that urges them to perform pressure relief.” she said.
With WSET, alarms are automatically turned on every 15 to 30 minutes, depending on rehabilitation specialists’ advice, as a reminder for patients to conduct pressure relief activities. By using four pressure sensors placed at the most possible high-pressure development area of patients sitting in a wheelchair, the sensors in the system can detect changes in pressure relief activities and automatically deactivate the alarm.
“This entire system reduces the dependence on caregivers in ensuring patients conduct pressure relief activities regularly. All sensors are capable of being monitored in real-time on the WSET app that can be installed on any Android smartphone device,” she shared. Nurhani added that the location of sensor placement and mode of calibration were extensively researched to ensure maximal accuracy.
“Through multiple experiments, we have identified the optimal region of sensor placement on the bilateral ischial tuberosities (buttocks) and thigh area that is currently maintained as our default sensor placement installed within the WSET cushion. For calibration, we used force sensing resistance as a sensing element that is first calibrated by a standard procedure using load weighing between 1 N to 100 N to ensure that all sensors have the same sensitivity range,” she said. Currently, WSET has obtained ethics approval for use in clinical trials, which were conducted among real-life patients to ensure its reliability.
“Using the Xsensor mapping pressure system, a commercially available tool commonly used by medical practitioners and physiotherapists to detect interface pressure from 5 – 200 mmHg with the accuracy of ± 2 mmHg, we conducted a clinical trial consisting of five paraplegic spinal cord individuals to compare the results between Xsensor and WSET. Our findings revealed no significant differences between the results from both systems, proving the reliability of our system,” she said.
On the economical aspect, Nurhani shared that the WSET system was designed with low-cost materials and can be reused for multiple patients or even placed at rehabilitation centres nationwide. The system has a standardised design that can be applied to all types of wheelchairs. Like any other research project, she shared that there were setbacks encountered along the way.
“For this system, we had to design an Android app using MIT App Inventor that can set off an alarm every 15 minutes, start a countdown for 1 minute, stop the alarm once the linked sensors detect patients have conducted their pressure relief activities and finally automatically reset back to 15 minutes. As I am not very familiar with coding applications, this was a challenge for me that fortunately, with the help of my supervisor, I was able to overcome.”
Universiti Malaya (UM) Master of Systems Engineering graduate Norhani binti Md Nadzri (left) and UM Department of Biomedical Engineering Associate Professor Dr Nur Azah binti Hamzaid with winning the Gold Award of WSET in the 35th International Invention, Innovation & Technology Exhibition (ITEX) 2022.
The wheelchair seating training system (WSET).