Apparatus and methods related to an underbody support for supporting a body of a being, such as during surgery to prevent contact pressure injuries. In certain embodiments, the underbody support may include one or more inflatable chambers enclosing a volume. At least one of the inflatable chambers may include one or more compression sensitive switches for monitoring the volume of the inflatable chamber, and the one or more compression sensitive switches may be located within the inflatable chamber. In some embodiments the one or more compression sensitive switches are sized to close when the said inflatable chamber is deflated to a desired residual volume.