Visible and infrared optical probes for hemodynamic parameters assessment

Four optical probes were developed to measure the arterial distension waveform generated by the ventricular contraction and assess clinically relevant information. The pressure wave propagates through the arterial tree and can be measured in the peripheral arteries. The probes make use of two distinct photo-detectors: planar and avalanche photodiodes. Independently, two different light sources were tested: visible and infrared light. Performance of the probes was evaluated in a test setup that simulates the fatty deposits commonly seen in the obese, between skin and the artery. The probes show good overall performance in the test setup with less than 8% root mean square error (RMSE). However, the probes lit with IR sources show better results for the more extreme cases, with a better resolution in the waveform, higher definition of notable points and higher SNR when compared to the visible source signals. In vivo, the IR probes allow easier waveform detection, even more relevant with the increasing of the deposit structures.