Patent ID: 8832885

Claim:
A patient support for supporting a patient, said patient support comprising: an inflatable mattress having a plurality of rows of bladders forming at least part of a patient support surface and extending laterally across the mattress, each row having a plurality of bladders wherein each row is formed by a plurality of adjacent bladders, said bladders forming at least two zones, and each bladder in each respective zone being in fluid communication with each other bladder in said respective zone; a pneumatic system for inflating said bladders; and a control system, said control system including a first sensor associated with a first respective bladder of a first respective zone and a second sensor associated with a second respective bladder of a second respective zone, each of said first and second sensors including an emitter and a receiver, each emitter directing light into its respective bladder, and each receiver being adjacent its associated emitter and receiving a reflection from the light of its associated emitter directed into its respective bladder, said control system further including a reference receiver associated with one of said first and second sensors to account for decay in said emitter of said one of said first and second sensors, and said control system determining the immersion of a patient into said mattress in each of said zones based on the reflections received by said receivers, and said control system comparing the immersions at each respective zone with a defined minimum immersion for each respective zone, and when said control system determines that the immersion of one of said respective bladders deviates from its defined minimum immersion said control system adjusts the pressure in the one of said respective bladders.