Mattress bladder arrangement for chair bed

A patient support system comprising

• a patient support apparatus having a head end and a foot and including an articulatable deck having a head-deck section, a seat-deck section, and a foot-deck section, the articulatable deck being movable between a lie-flat configuration and a chair egress-configuration,
• wherein in the lie-flat configuration of the articulatable deck, the head-deck section, the seat-deck section, and the foot-deck section are each in a generally horizontal orientation with the head-deck section being in a lowered position with respect to the seat-deck section and the foot-deck section being in a raised position with respect to the seat-deck section,
• wherein in the chair-egress configuration of the articulatable deck, the head-deck section is in a raised position extending generally upwardly with respect to the seat-deck section and the foot-deck section is in a lowered position extending generally downwardly with respect to the seat-deck section so that a patient supported in a sitting position by the seat-deck section of the articulable deck is able to exit from the patient support apparatus to a standing position from the foot end of the patient support apparatus,
• a support surface including one or more seat-support bladders supported by the seat-deck section, one or more head-support bladders supported by the head-deck section, and one or more foot-support bladders supported by the foot-deck section,
• a pneumatic system comprising an air source coupled to the one or more seat-support bladders, the one or more head-support bladders, and the one or more foot-support bladders,
• a controller coupled to the pneumatic system to control operation of the pneumatic system, wherein the controller is configured to operate the pneumatic system so that the air source maintains inflation of the one or more seat-support bladders, the one or more head-support bladders, and the one or more foot-support bladders when the articulatable deck is in the lie-flat configuration, wherein the controller is configured to operate the pneumatic system to at least partially deflate the one or more foot-support bladders as the articulatable deck moves from the lie-flat configuration to the chair-egress configuration, and
• at least one boost bladder adjacent the one or more head-support bladders, the at least one boost bladder being inflatable by the air source of the pneumatic system to increase spacing between the patient's torso and the head-deck section when the articulatable deck is in the chair-egress configuration to assist the patient in exiting the patient support apparatus.