Development and testing of a wearable laser speckle device for detection of postpartum hemorrhage (Keynote Presentation)

Postpartum hemorrhage (PPH) is the leading cause of maternal mortality globally. Importantly, PPH has been noted as the most preventable cause of maternal mortality, and the leading factors causing preventable PPH are delays in diagnosis and treatment. Thus, there is an urgent need for an early and accurate PPH alert system that can be successfully deployed at the point of care. To this end, we developed a low-cost (<$150), wearable optical device that continuously monitors peripheral perfusion on the wrist via the laser speckle flow index (LSFI) to detect hemorrhage-induced peripheral vasoconstriction. The laser speckle imaging system was designed using a Raspberry Pi Camera (V2) and a laser diode. The system is controlled by a Raspberry Pi Zero computer. The device contains no consumables, and is reusable and compact. It can capture, process, and display LSFI signal for near real-time data visualization. The sensor has been successfully tested in a swine hemorrhage model, human blood donor model, and cesarean deliveries with high correlation (Spearman rho >0.9) to net fluids. This progress provides a framework for a novel low-cost and noninvasive technology that identifies ongoing blood loss rapidly, with the goal of reducing the unacceptably high rates of global maternal morbidity and mortality caused by hemorrhage in low- and high-resource settings alike.