1. A method for processing physiological monitoring signals, comprising: monitoring a subject by: receiving a first electronic signal from a first sensor located at a first body site of a subject; and receiving a second electronic signal from a second sensor located at a second body site of a subject, wherein the second body site is different from the first body site; using processor equipment for: calculating a Lissajous figure based at least in part on the first and second electronic signals; identifying at least one feature of the Lissajous figure; and determining information regarding the monitoring of the subject based at least in part on the at least one feature; and outputting at least a portion of the information to an output device.