US Patent 9943172 Mattress topper with varying flow resistance

A bed comprises a mattress and a topper resting atop the mattress and extending in longitudinal and lateral directions. The topper has a fluid flowpath having an inlet and an outlet. The flowpath exhibits a nonuniform resistance to fluid flow in at least one of the longitudinal and lateral directions. The bed also includes a blower connected to the inlet for supplying air to the flowpath. The resistance may be a monotonically varying resistance to fluid flow in at least one of the longitudinal and lateral directions and configured to preferentially drive fluid flow through the topper so that a larger proportion of the fluid flowing through the topper flows under a target region and a relatively smaller portion bypasses the target region.