Patent ID: 8437824

Claim:
A method for monitoring a patient, comprising: (a) measuring a first time-dependent signal by detecting a first radiation emitted by a first radiation source after the first radiation passes through a portion of the patient; (b) measuring a second time-dependent signal by detecting electrical signals from the patient using at least two electrodes, and processing the electrical signals with an electrical circuit to form the second time-dependent signal; (c) measuring a time-dependent motion signal with at least one motion sensor; (d) processing the first and second time-dependent signals to determine a transit time corresponding to a single heartbeat in a collection of heartbeats; (e) processing multiple transit times, each corresponding to a heartbeat within the collection of heartbeats, with a first algorithm to identify a portion of the first time-dependent signal that may be affected by motion; (f) analyzing the time-dependent motion signal to estimate if the portion of the first time-dependent signal is affected by motion; (g) applying a mathematical filter that processes both the portion of the first time-dependent signal and a numerical template representing a pre-determined portion of a time-dependent signal if it is determined that the portion of the first time-dependent signal is affected by motion; (h) determining a filtered version of at least a portion of the first time-dependent signal with the mathematical filter; and (i) processing the filtered version of the first time-dependent signal to determine a oxygen saturation value for the patient.