Abstract: The present invention relates to systems and methods for comparing photoplethysmography (PPG) signals from an individual with signals from a secondary respiration sensor secured to the individual to determine whether effective respiration has occurred or whether the individual has apnea, hypopnea, or other respiratory distress.

Abstract: Provided according to embodiments of the invention are methods of monitoring the direction of blood flow that include processing with a computer photoplethysmography (PPG) signal streams from a sensor array on a body site of the individual to determine the direction and/or velocity of the blood flow at the body site of the individual. In some embodiments, direction of the blood flow at the body site is determined by the phase difference between at least three PPG signal streams from the sensor array, wherein the at least three PPG signal streams are generated from emissions of the at least three emitters.

Abstract: Provided according to embodiments of the invention are systems for monitoring a physiological state of an individual that include a PPG sensor, which optionally includes an auxiliary physiological sensor integrated with or connected thereto; a first signal processing device in electronic communication with the PPG sensor, whereby the PPG sensor transmits PPG signals to the first signal processing device; and a second signal processing device that detects at least a portion of the signals transmitted by the PPG sensor to the first signal processing device, at least a portion of signals transmitted by the auxiliary physiological sensor, or both. Related methods are also provided herein.

Abstract: Provided according to embodiments of the invention are photoplethysmography (PPG) sensors, systems and accessories, and methods of making and using the same. In some embodiments of the invention, the PPG sensors include a clip body that includes a first end portion and a second end portion; a flex circuit attached or adjacent to the clip body, and an elastomeric sleeve that envelops (1) at least part of the first end portion and at least part of the flex circuit attached or adjacent thereto; or (2) at least part of the second end portion and at least part of the flex circuit attached or adjacent thereto.

Abstract: Provided herein are methods and systems for validating and interpreting respiratory signals in order to provide comprehensive non-invasive methods to monitor patients at risk for respiratory depression and apnea. In the present invention, data from multiple respiratory monitoring technologies (or from multiple channels of one monitoring technology) is fused so that the patient's true respiratory state may be elucidated.