Mukul Julius Rocque

Calibration of Contactless Pulse Oximetry.

BACKGROUND: Contactless, camera-based photoplethysmography (PPG) interrogates shallower skin layers than conventional contact probes, either transmissive or reflective. This raises questions on the calibratability of camera-based pulse oximetry. METHODS: We made video recordings of the foreheads of 41 healthy adults at 660 and 840 nm, and remote PPG signals were extracted. Subjects were in normoxic, hypoxic, and low temperature conditions. Ratio-of-ratios were compared to reference SpO2 from 4 contact probes. RESULTS: A calibration curve based on artifact-free data was determined for a population of 26 individuals. For an SpO2 range of approximately 83% to 100% and discarding short-term errors, a root mean square error of 1.15% was found with an upper 99% one-sided confidence limit of 1.65%. Under normoxic conditions, a decrease in ambient temperature from 23 to 7°C resulted in a calibration error of 0.1% (±1.3%, 99% confidence interval) based on measurements for 3 subjects. PPG signal strengths varied strongly among individuals from about 0.9 × 10−3 to 4.6 × 10−3 for the infrared wavelength. CONCLUSIONS: For healthy adults, the results present strong evidence that camera-based contactless pulse oximetry is fundamentally feasible because long-term (eg, 10 minutes) error stemming from variation among individuals expressed as A*rms is significantly lower (<1.65%) than that required by the International Organization for Standardization standard (<4%) with the notion that short-term errors should be added. A first illustration of such errors has been provided with A**rms = 2.54% for 40 individuals, including 6 with dark skin. Low signal strength and subject motion present critical challenges that will have to be addressed to make camera-based pulse oximetry practically feasible.

Fully automated contactless respiration monitoring using a camera

Reliable monitoring of respiration rate in low acuity settings can be an early predictor of physiological deterioration. A fully automated low cost respiration monitoring algorithm developed using a contactless camera is presented in this article. The algorithm was evaluated on adults and neonates to test home wellness applications. The results match very well with references while outperforming existing algorithms, showing the algorithms robustness and feasibility.

Monitoring Patients in the Wild

This demo will show an abridged version of aresearch prototype for remotely monitoring the physiologicalstatus of patients in the wild. In the demo, we will show real timemeasurement of pulse and breathing rates of multiple subjectsin an uncontrolled setting. The applications of this system arewide, a typical example being the monitoring of patients in thewaiting room of a hospital’s emergency department