Functional areas of the cushion are created by three types of foam: soft foam for the decubitus-sensitive area of the ITs; medium foam for the thigh trough, pelvic bucketing and pre-ischial bar; and firm foam for the perimeter and the medial thigh separator.
Bonding Meridian foam to coated fabric makes the cushion hold air. A valve releases air to immerse the user in the foam, the foam conforms to the user, and the user’s weight is distributed over the surface of the cushion.
Independent research has shown VARILITE Air-Foam Floatation to be the #1 impact and vibration dampening technology (RESNA 2000).
Front and rear chambers permit independent adjustment of the pelvis and thighs, quickly and easily, while the client is seated. The rear chamber allows maximum immersion of the pelvis for better pressure distribution. The front chamber allows maximum loading of the thighs which reduces pressure on the ITs. The Meridian’s dual-chambered design promotes a neutral pelvis position, especially important for clients prone to extensor tone or thrusting. The thigh and pelvic chambers form a pre-ischial ridge which prevents the ITs from sliding forward, preventing a posterior pelvic tilt and sacral sitting. Releasing more air from the pelvic chamber than the thigh chamber provides added postural support by creating dump or squeeze that “holds” the client in place. Additional pelvic positioning can be obtained by combining a VARILITE Wave positioning base with the Meridian.
Meridian foam is bonded to four-way-stretch knit fabric for maximum conformity during immersion. The fabric is puncture and water resistant.
The Meridian is available with a mesh or incontinence cover with breathable four-way-stretch material. Reticulated foam inside promotes air exchange and improves pressure distribution. The underside is a rugged nonslip material with hook and loop for added security. Meridian cover meets ISO 7176-16 ignition resistance standards for upholstered wheelchair components. Machine washable.
Positioning supports improve stability, which is important for users with compromised sitting balance or who transfer frequently. Multi-stiffness foam provides support as the user is immersed in the cushion. Medial and lateral supports minimize internal and external lower extremity rotation. Pelvic bucketing and a pre-ischial ridge help maintain pelvic position, and thigh troughs promote a neutral femoral position.
The Meridian uses VARILITE two-way air valves. Sitting on a fully inflated cushion, the user opens the right valve and releases air from the pelvic chamber. Optimal immersion is achieved when there is 1/2 inch (13 mm) of air and foam between the ITs and the wheelchair’s seating surface. Immersing the pelvis while the thigh chamber is fully inflated creates a wedge effect that shifts the load from the ITs to the thighs. The user can decrease the amount of wedge achieved by opening the left valve to release air from the thigh chamber.