In-Suit Detection of Venous Gas Emboli

Future manned missions to the moon and Mars will be resource constrained. Crew time and oxygen are among the most important resources for any manned mission. Unfortunately, current strategies—dentriogenation by long duration oxygen prebreathe protocols—for mitigating the risk of decompression sickness (DCS) during extravehicular activities (EVA) consume significant time and oxygen. NASA needs new and better strategies for monitoring, mitigating, and managing DCS risk. Creare proposes to adapt our diver-worn DCS risk assessment tool for EVA. Our proposed Body-worn Emboli Notification Device (BEND) will non-invasively monitor the astronaut’s blood for venous gaseous emboli (VGE) via two different ultrasound techniques: Doppler and dual-frequency ultrasound (DFU). It has long been established that there is a very strong correlation between VGE and DCS and that monitoring VGE is a promising avenue for assessing DCS risk in real-time. In addition to monitoring for VGE, BEND will use DFU to monitor microbubbles in the tissue and in the blood. DFU does not require precise alignment with the heart or veins to function (reducing the amount of crew time needed to properly don the device) and DFU requires minimal embedded signal processing (reducing the necessary processing power, which reduces the device size while increasing battery life). In Phase I, we will advance the TRL of our device from 3 to 5 by adapting our existing design for the EVA suit environment, fabricating prototypes, validating prototype performance in the laboratory in reduced pressure oxygen and freefall environments, and delivering a prototype to NASA for evaluation. In Phase II, we will increase our TRL to 6 by iterating the system design, fabricating high fidelity prototypes, and demonstrating performance in mission-simulating environments in the laboratory, in human subject flights in hypobaric chambers, and in an animal model of altitude DCS.