An apparatus for performing diffuse optical imaging of blood circulation in a patient, said apparatus comprising: at least one sensor module comprising at least one optical source and at least one photodetector; an interface electronics module; and means for communicating at least one selected from the group consisting of control signals and measurement data between said sensor module and said interface electronics module; wherein said apparatus further comprises a membrane releasably secured to the skin of the patient, said membrane being configured to releasably secure said at least one sensor module to said membrane such that said at least one sensor module is disposed against the skin of the patient.

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.

A system for using an oximeter to provide blood pressure readings relies on a comparative interface between readings of a patient's blood flow waveform (oximeter) and blood pressure (sphygmomanometer) in his/her vasculature. For this purpose, a steady state condition is identified by calibrating a blood flow measurement A from the oximeter with a simultaneously obtained blood pressure measurement P from the sphygmomanometer. Further, using these simultaneous measurements, a blood pressure model is created that is based on the steady state. Thereafter, blood flow waveform readings from the oximeter are correlated with the steady state model to provide continuous blood pressure readings.

Optical coherence tomography (herein “OCT”) based analyte monitoring systems are disclosed. In one aspect, techniques are disclosed that can identify fluid flow in vivo (e.g., blood flow), which can act as a metric for gauging the extent of blood perfusion in tissue. For instance, if OCT is to be used to estimate the level of an analyte (e.g., glucose) in tissue, a measure of the extent of blood flow can potentially indicate the presence of an analyte correlating region, which would be suitable for analyte level estimation with OCT. Another aspect is related to systems and methods for scanning multiple regions. An optical beam is moved across the surface of the tissue in two distinct manners. The first can be a coarse scan, moving the beam to provide distinct scanning positions on the skin. The second can be a fine scan where the beam is applied for more detailed analysis.

A wearable device includes a housing with a window and an electronic module supported by the housing. The electronic module includes a photoplethysmography sensor, a motion sensor, and a signal processor that processes signals from the motion sensor and signals from the photoplethysmography sensor. The signal processor is configured to remove frequency bands from the photoplethysmography sensor signals that are outside of a range of interest using a band-pass filter to produce pre-conditioned signals, and to further process the pre-conditioned signals using the motion sensor signals to reduce motion artifacts from footsteps during subject running. The device includes non-air light transmissive material in optical communication with the photoplethysmography sensor and the window that serves as a light guide for the photoplethysmography sensor. The window optically exposes the photoplethysmography sensor to a body of a subject wearing the device via the non-air light transmissive material.

Systems and methods for path length selected diffuse correlation spectroscopy (PLS-DCS) are disclosed. The systems and methods are suitable for measuring dynamics of a target medium. The systems and methods can utilize light sources having a coherence length that is shorter than a path length distribution of the target medium and can utilize a reference optical path to interferometrically detect PLS-DCS signals. The coherence length and reference path length can be selected to provide sensitivity to portions of the target medium that correspond to a desired path length distribution.

An obstructive sleep apnea detection device including an optical engagement surface adapted to engage a user's skin; a light source adapted to emit light from the optical engagement surface; a photodetector adapted to detect light at the optical engagement surface and to generate a detected light signal; a position sensor adapted to determine patient sleeping position; a controller adapted to determine and record in memory blood oxygen saturation values computed from the detected light signal and user position information from the position sensor; and a housing supporting the optical engagement surface, the photodetector, the light source, the position sensor, and the controller.

The invention relates to a method for determining the occurrence of a vascular collapse of a blood vessel in or on the eye. According to the invention, it is proposed that the vascular collapse be determined from a measured temporal change of blood flow in the blood vessel.

An oxygen-sensing assembly for attachment to a urinary catheter may include a housing having a flow pathway extending between an inlet end and an outlet end thereof, an oxygen sensor in operable communication with the flow pathway of the housing, the oxygen sensor configured to detect oxygen levels of a fluid flowing through the flow pathway and a flowrate sensor configured to detect a flowrate of the fluid flowing through the flow pathway. A risk of acute kidney injury may be determined based on the mass flowrate of oxygen through the flow pathway, determined based on the detected oxygen levels and the flowrate of the fluid through the flow pathway. Related catheter assemblies and methods are also disclosed.

A device for providing reference information in laser speckle medical imaging of tissue of a subject can include a support that includes a marker for image recognition and a speckle target region that is nontransparent to light in a first illumination wavelength range and that generates a speckle pattern when illuminated with light in the first wavelength range. The support can be configured to be attachable to tissue of the subject.