Autism is a very common disorder among children, with approximately 1 in every 110 children diagnosed. Children with autism typically have problems processing sensory inputs correctly, which can have a negative effect on the child’s behaviors. In order to help this problem, sensory-based interventions (SI) are used. Sensory-based interventions often apply sensory input to the child to modulate the neurological response to these sensory inputs. Multiple forms of sensory based therapy interventions are used, including weighted and compression vests, which apply deep pressure to a child’s torso. Based on an understanding of sensory receptors and the somatosensory system, the effectiveness from these vests wears off after a short time period. Although there is no proven theory for the mechanism behind sensory integration, it is believed that deep pressure applied to the child travels through the dorsal column in the spinal cord which overrides pain and discomfort in another spinal column. The mechanoreceptors which sense the deep pressure rapidly adapt to this sensory input, which could explain why the effectiveness of the vest wears off after approximately 20 minutes. Applying dynamic pressure could potentially keep these mechanoreceptors continuously responding to the deep pressure, which could increase the effectiveness of the interventions. In hopes of creating a more effective way to apply compression to the trunk, we designed a dynamic compression vest.
A first prototype of a dynamic compression vest with air bladders inflated and deflated through pneumatic and control systems was designed in a senior capstone class, ME 565, but the vest did not meet many of the initial requirements. The shortcomings of the vest motivated the need for a new design that could be used to address questions associated with SI. The second prototype, which was built for this thesis, reduced the size of the components, and moved the pneumatic and electrical systems to a box on the vest. The control system was completely redesigned, with the vest controlled through LabVIEW, which made it easy to change timing and pressure parameters. Pressure feedback was included in the system which gave more accurate control than the first prototype which used a feed-forward system. This vest provided the ability change the parameters so the effects of different pressures and timing inputs could be investigated.
We performed tests to determine the correlation between the air pressure in the bladders and contact pressure applied from the vest. This contact pressure is the mechanism that is applying the intermittent compression to the child’s trunk. The vest was tested on healthy volunteers to ensure the safety of the vest before we test on children. The majority of the subjects preferred the 0.2 – 0.4 psi range compared to 0.3 – 0.5 psi, which helps establish good pressure ranges.
This vest can now be used in multiple studies to determine the effectiveness of using dynamic compression as a form of SI. The vest can also be used to determine effective levels of pressure and the amount of time the pressure should be applied.