A backrest of a bed is pivotable with respect to a bed frame. A backrest actuator assembly connects the backrest to the bed frame. The backrest actuator assembly is configured to raise and lower the backrest with respect to the bed frame by way of an actuator. The backrest actuator assembly is further configured with a lockable damper to release the backrest to lower due to gravity over a damped range of motion. The backrest can be so lowered during an emergency, such as an emergency that requires administration of CPR to the beds occupant. The lockable damper can stop the lowering of the backrest at any position along the damped range of motion. After an emergency lowering, the backrest actuator assembly can automatically reset to a normal operation state.
